The Official "Why VTEC doesn't Engage" Thread
04-12-2004, 07:06 AM
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The Official "Why VTEC doesn't Engage" Thread
I think we should get some info together and post up some common problems, and maybe even have people post in here that have had problems in the past and how they fixed them, it just seems there are alot of people doing swap or that are just having problems getting it to work correctly
i will start gathering some information but i got some work to do, in the mean time if anyone has info to add please post
<U>Problems and causes i have run into before:</U>
Problems usualy brake down into 2 categories and sometimes include both: mechanical and electrical. the first thing when wiring in a swap or diagnosing a problem is to check and recheck and check 50 trrilion times your wiring, and run new wires if you have to, its very important that electrical is right first. mechanical problems can sometimes be the hardest to diagnois, but there are ways of testing certian issues
*CELs and LIMP MODE, any number of things can throw you into limp mode and you definatly won't have vtec. most likely if you have a CEL fix that first then worry about VTEC. CEL can be a great indicator as to whats going on, and that light is lit for a reason. even when people say, "i have a CEL but thats a different issue" fix that FIRST, then worry about vtec. many codes that are set have alot to do with why vtec isn't working. and if your car is most definatly not acting right take apart the dash and check that your CEL light is not burnt out. it should light up when you first turn the key on.
*VSS/ SPEEDO if your car loses its speed reference vtec will not engauge. the ecu will see it just as if you were sitting still reving the engine, no vtec
*TACHOMETER i have seen a case where there was a problem with a persons tach, and i don't know where the wiring problem was, but if the ecu doesn't have a tach reference , then how is it going to know when you reach proper rpm.. exactly
*OIL, if you don't have the correct oil presure no vtec: possible causes: dented or damaged oil pan (as members have said before) , not enough oil, or oil is so old and crappy it is thin as water
*VTEC OIL PRESURE switch, The vtec oil presure switch is what feeds back information the the computer to tell it wether or not the opening of the solinoid has alowed high presure oil into the vtec oil gallerys. Once the solinoid opens oil shoud presurize the vtec oil ways pushing the locker pins into place while the oil presure sensor right next to the vtec solinoid feeds back info to the ecu.
*TEMP, the cars coolant temp needs to be at a certian temp for vtec to engage, if any of your temperature sensors are screwed up that is another possibility to look into
*VTEC SOLINOID GASKET/screen, i have heard and seen many cases where a cloged or dirty screen that is part of the vtec soliniod gasket caused vtec to not engage or be intermitant.
*THROTTLE POSITION, if your throwing a code for the TPS being bad or wacky this can also cause intermitant or no engagement, from my expermiments, whether vtec engauges or not is throttle position dependent.
<U>Testing the mechanics of VTEC</U>
*You want to check are that you have the appropriate oil presure at head when approching the rpm vtec engauges. I have seen motors where their just wasn't enough oil press and it doesn't throw any CEL but vtec just doesn't work and you hit the 6500 rev limit. The way to check is take the 10mm bolt out of the head that is on the front left if you are facing the motor. This bolt gives you access to the oil way of vtec, this is the same bolt that you remove to do the air presure test listed below. But anway you need to get a gauge that screws into the oil port. Now from here you have two choices. once you have the gauge installed you can either raise the car up and run the car in gear in order to simulate the speed so the vtec solinoid will open and then measure the presure OR you can disconnect the 1 pin connector from the vtec solinoid and aply batery voltage tot he solinoid in order to open it so oil can/should flow into the vtec oil gallerys. The test has to have the motor reving at least up to if not beyond 5000rpm in order to get an accurate oil reading. now what ever way you shose to get the solinoid to open with the car runing is up to you but at 5000rpm you should read a minimum of 60 psi of press at that port. if you do end up having enough oil press i would investigate a bad vtec oil presure sensor. Also not having enough oil presure can also account for "Late" engaugement, where you reach the apropriate press after the preset engaugement point and then the ecu alows vtec to engauge because the required oil presure has been met.
*Secondly you want to make sure that your solinoid is opperational, take it off and using a 12 volt source and a ground make sure that the solinoid operates quickly and smoothly when 12v is applied. this is the valve and if it isn't working vtec won't either
*Third if all else fails you can check that vtec mechanics work by using air presure(this test should then be followed up by the oil presure test) Take off the valve cover, take the plug out of the front of the head next to the header, either find a fitting that you can adapt your air hose to screw in the head or get a blow gun with a rubber tip. with another person you have to block the bleed hole on the 5th cam cap and while applying 40-60 spi of air presure , slowly crank over the motor using the main crank pully and watch to see that all 3 rockers lock togther and start to follow the middle lob, the VTEC lob. you may even hear a tiny click as the pins in the rockers lock the 3 togther. also you will be able to tell that the vtec lobe is being followed as the lift or how far the valves are pushed down is much greater. with the appropriate air presure and if everything is workign corectly every valve should be following the vtec lob. make sure that you have a good air compresor that can keep up with keeping a presure of 40-60 psi. if you don't have luck try raising the presure a littlbe bit, but i wouldn't go much hiogher than 80 psi.
once you have verified that all the maechanics are working : vtec solinoid, oil press, and valve assembly then you can move from there and see where the problem lies in wiring.
<U>Other Info</U>
things i haven't seen but are possible are, a faulty vtec solnoid, vtec oil presure sensor, and if your ecu is not detecting the RPM signal.
more vtec presure switch info: the vtec presure switch is jsut that , a switch , its on or off deppending on the oil presure. the ecu sends out about a 10v signal from 1 pin and runs it thru the presure switch back tot he ecu. if the presure is to low the switch stays closed and the ecu "sees" this by the 10v returning, after the vtec solinoid opens the ecu is expecting to see that the switch is opend by the oil presure and for its 10v feed back to disapear.
THE JUMPER WIRE THEORY:if you just jumper the wire your simulating a switch that never opens, on the flip side however if you just disconnect it i think the ecu is smart enough to know that before the engaugement point it wasn't "seeing" its 10v feedback so it throws a vtec malfunction. doing some testing you can get a multimeater: remove the 2p connector from the vtec presure switch , measure voltage with the ignition on between the two pins on the plug you should measure about 10v, this will indicate the wires to the ecu for the vtec presure switch are good, then turn the key off and measure for continuity between the two terminals on the vtec presure switch. seeing as this is a switch its natural state is closed you should measure close to no resistance thru the switch. now this info just means the switch is good if you read continuity thru it but that doesn't mean that the switch is opening when it is supposed to. i would investigate the presure switch further if the oil presure tests are done and found that the correct oil presure is indeed there.
also where you car is hitting its rev limiter can give away even more information, if you can only rev to 6500 and then hit a fuel cut then your not in limp mode but one of the requirements for vtec to engauge has not been met.. such as temp, oil press speed, etc..
IAB solenoid activates on a P13 (91-96) at 4600, and 4900 on a P5M (97-01)
VTEC solenoid activates on a P13 (91-96) at 4900, and 5200 on a P5M (97-01)
but if you car is only reving to (i think limp mode if 5000 rpm) then you have something seriously prohibiting the car, and most likely almost definatly your CEL should be on, and like i said fix and present codes befor eyou worry about VTEC.
and NO vtec does not engauge if you sitting still in your car and reving it, the secondary runners will open up, but the vtec soliniod will not open.
which brings me to another point, part of what makes vtec work well is the fact that right before the secondary cam profiles engauge the secondary runners in the intake manafold open up to accomadate the engines greater demand for air flow when in VTEC. some times there maybe something wrong with the wiring that tells the IAB soliniod to remove vacume from the diaphram that holds them closed. If anything is wrong with the IAB system then that can cause vtec to feel like it is not engauging. The Iabs are rpm dependant only, and the do open if you reving the car in neutal. THe Iabs are held closed when the car is idling by vacume and continue to be held closed by vacume stored in the small canaster under the intake manifold so you will have vacume to the required rpm even at WOT. With key off and no vacume the IABs open due to a spring. so once vacume is removed they just go to their rest state which is open.
<U>Wiring info </U>
credit to jdmlude_dude ::check here for more info https://honda-tech.com/zerothread?id=833163
There are 2 wire tha come out of the vtec pressure switch, one is hot and goes to pin D6 and the other can just be grounded off on the motor or on the chassis
A4 = Vtec Solenoid
D6 = Vtec Oil Pressure Switch
if you take the ecu and look at the pins as if it were in the car, say you lay it on a table with the top facing up and you look as the pins, the "A" pin numbers will start on the very right, Example:
Top side w/ the sticker
----------------D6------------------------------------A4---
l --------------\/---- -------------- -------------------\/-- l
l l oo . . . . . . . . o ll . . . . . . . . ll oo . . . . . . . . ooo l l
l l oo . . . . . . . . o ll . . . . . . . . ll oo . . . . . . . . ooo l l
l -------------------- -------------- ----------------------- l
-------------------------------------------------------------
A fellow user also alreted me to the fact that sometimes even if everything else is 100% even wiring the ECU pins may not be making contact. so make sure that you check that your using the correct pins if you wired vtec in and make sure they are the correct ecu honda pins and none are opened up at all.
just a last note, i haven't covered ever possible cause in this thread, but im pretty sure 90% of people problems can be fixed or majorly narrowed down by going thru everything i have talked about. I aam always here to try and help people out, but don't post and ask for help if you haven't already tried basically everything here, or you are confused. This thread is based off of information i gathered and read about and is here for you to learn from and help yourself. i can assit but can't fix everyones problems.
Modified by prelittlelude at 2:08 PM 8/8/2006
i will start gathering some information but i got some work to do, in the mean time if anyone has info to add please post
<U>Problems and causes i have run into before:</U>
Problems usualy brake down into 2 categories and sometimes include both: mechanical and electrical. the first thing when wiring in a swap or diagnosing a problem is to check and recheck and check 50 trrilion times your wiring, and run new wires if you have to, its very important that electrical is right first. mechanical problems can sometimes be the hardest to diagnois, but there are ways of testing certian issues
*CELs and LIMP MODE, any number of things can throw you into limp mode and you definatly won't have vtec. most likely if you have a CEL fix that first then worry about VTEC. CEL can be a great indicator as to whats going on, and that light is lit for a reason. even when people say, "i have a CEL but thats a different issue" fix that FIRST, then worry about vtec. many codes that are set have alot to do with why vtec isn't working. and if your car is most definatly not acting right take apart the dash and check that your CEL light is not burnt out. it should light up when you first turn the key on.
*VSS/ SPEEDO if your car loses its speed reference vtec will not engauge. the ecu will see it just as if you were sitting still reving the engine, no vtec
*TACHOMETER i have seen a case where there was a problem with a persons tach, and i don't know where the wiring problem was, but if the ecu doesn't have a tach reference , then how is it going to know when you reach proper rpm.. exactly
*OIL, if you don't have the correct oil presure no vtec: possible causes: dented or damaged oil pan (as members have said before) , not enough oil, or oil is so old and crappy it is thin as water
*VTEC OIL PRESURE switch, The vtec oil presure switch is what feeds back information the the computer to tell it wether or not the opening of the solinoid has alowed high presure oil into the vtec oil gallerys. Once the solinoid opens oil shoud presurize the vtec oil ways pushing the locker pins into place while the oil presure sensor right next to the vtec solinoid feeds back info to the ecu.
*TEMP, the cars coolant temp needs to be at a certian temp for vtec to engage, if any of your temperature sensors are screwed up that is another possibility to look into
*VTEC SOLINOID GASKET/screen, i have heard and seen many cases where a cloged or dirty screen that is part of the vtec soliniod gasket caused vtec to not engage or be intermitant.
*THROTTLE POSITION, if your throwing a code for the TPS being bad or wacky this can also cause intermitant or no engagement, from my expermiments, whether vtec engauges or not is throttle position dependent.
<U>Testing the mechanics of VTEC</U>
*You want to check are that you have the appropriate oil presure at head when approching the rpm vtec engauges. I have seen motors where their just wasn't enough oil press and it doesn't throw any CEL but vtec just doesn't work and you hit the 6500 rev limit. The way to check is take the 10mm bolt out of the head that is on the front left if you are facing the motor. This bolt gives you access to the oil way of vtec, this is the same bolt that you remove to do the air presure test listed below. But anway you need to get a gauge that screws into the oil port. Now from here you have two choices. once you have the gauge installed you can either raise the car up and run the car in gear in order to simulate the speed so the vtec solinoid will open and then measure the presure OR you can disconnect the 1 pin connector from the vtec solinoid and aply batery voltage tot he solinoid in order to open it so oil can/should flow into the vtec oil gallerys. The test has to have the motor reving at least up to if not beyond 5000rpm in order to get an accurate oil reading. now what ever way you shose to get the solinoid to open with the car runing is up to you but at 5000rpm you should read a minimum of 60 psi of press at that port. if you do end up having enough oil press i would investigate a bad vtec oil presure sensor. Also not having enough oil presure can also account for "Late" engaugement, where you reach the apropriate press after the preset engaugement point and then the ecu alows vtec to engauge because the required oil presure has been met.
*Secondly you want to make sure that your solinoid is opperational, take it off and using a 12 volt source and a ground make sure that the solinoid operates quickly and smoothly when 12v is applied. this is the valve and if it isn't working vtec won't either
*Third if all else fails you can check that vtec mechanics work by using air presure(this test should then be followed up by the oil presure test) Take off the valve cover, take the plug out of the front of the head next to the header, either find a fitting that you can adapt your air hose to screw in the head or get a blow gun with a rubber tip. with another person you have to block the bleed hole on the 5th cam cap and while applying 40-60 spi of air presure , slowly crank over the motor using the main crank pully and watch to see that all 3 rockers lock togther and start to follow the middle lob, the VTEC lob. you may even hear a tiny click as the pins in the rockers lock the 3 togther. also you will be able to tell that the vtec lobe is being followed as the lift or how far the valves are pushed down is much greater. with the appropriate air presure and if everything is workign corectly every valve should be following the vtec lob. make sure that you have a good air compresor that can keep up with keeping a presure of 40-60 psi. if you don't have luck try raising the presure a littlbe bit, but i wouldn't go much hiogher than 80 psi.
once you have verified that all the maechanics are working : vtec solinoid, oil press, and valve assembly then you can move from there and see where the problem lies in wiring.
<U>Other Info</U>
things i haven't seen but are possible are, a faulty vtec solnoid, vtec oil presure sensor, and if your ecu is not detecting the RPM signal.
more vtec presure switch info: the vtec presure switch is jsut that , a switch , its on or off deppending on the oil presure. the ecu sends out about a 10v signal from 1 pin and runs it thru the presure switch back tot he ecu. if the presure is to low the switch stays closed and the ecu "sees" this by the 10v returning, after the vtec solinoid opens the ecu is expecting to see that the switch is opend by the oil presure and for its 10v feed back to disapear.
THE JUMPER WIRE THEORY:if you just jumper the wire your simulating a switch that never opens, on the flip side however if you just disconnect it i think the ecu is smart enough to know that before the engaugement point it wasn't "seeing" its 10v feedback so it throws a vtec malfunction. doing some testing you can get a multimeater: remove the 2p connector from the vtec presure switch , measure voltage with the ignition on between the two pins on the plug you should measure about 10v, this will indicate the wires to the ecu for the vtec presure switch are good, then turn the key off and measure for continuity between the two terminals on the vtec presure switch. seeing as this is a switch its natural state is closed you should measure close to no resistance thru the switch. now this info just means the switch is good if you read continuity thru it but that doesn't mean that the switch is opening when it is supposed to. i would investigate the presure switch further if the oil presure tests are done and found that the correct oil presure is indeed there.
also where you car is hitting its rev limiter can give away even more information, if you can only rev to 6500 and then hit a fuel cut then your not in limp mode but one of the requirements for vtec to engauge has not been met.. such as temp, oil press speed, etc..
IAB solenoid activates on a P13 (91-96) at 4600, and 4900 on a P5M (97-01)
VTEC solenoid activates on a P13 (91-96) at 4900, and 5200 on a P5M (97-01)
but if you car is only reving to (i think limp mode if 5000 rpm) then you have something seriously prohibiting the car, and most likely almost definatly your CEL should be on, and like i said fix and present codes befor eyou worry about VTEC.
and NO vtec does not engauge if you sitting still in your car and reving it, the secondary runners will open up, but the vtec soliniod will not open.
which brings me to another point, part of what makes vtec work well is the fact that right before the secondary cam profiles engauge the secondary runners in the intake manafold open up to accomadate the engines greater demand for air flow when in VTEC. some times there maybe something wrong with the wiring that tells the IAB soliniod to remove vacume from the diaphram that holds them closed. If anything is wrong with the IAB system then that can cause vtec to feel like it is not engauging. The Iabs are rpm dependant only, and the do open if you reving the car in neutal. THe Iabs are held closed when the car is idling by vacume and continue to be held closed by vacume stored in the small canaster under the intake manifold so you will have vacume to the required rpm even at WOT. With key off and no vacume the IABs open due to a spring. so once vacume is removed they just go to their rest state which is open.
<U>Wiring info </U>
credit to jdmlude_dude ::check here for more info https://honda-tech.com/zerothread?id=833163
There are 2 wire tha come out of the vtec pressure switch, one is hot and goes to pin D6 and the other can just be grounded off on the motor or on the chassis
A4 = Vtec Solenoid
D6 = Vtec Oil Pressure Switch
if you take the ecu and look at the pins as if it were in the car, say you lay it on a table with the top facing up and you look as the pins, the "A" pin numbers will start on the very right, Example:
Top side w/ the sticker
----------------D6------------------------------------A4---
l --------------\/---- -------------- -------------------\/-- l
l l oo . . . . . . . . o ll . . . . . . . . ll oo . . . . . . . . ooo l l
l l oo . . . . . . . . o ll . . . . . . . . ll oo . . . . . . . . ooo l l
l -------------------- -------------- ----------------------- l
-------------------------------------------------------------
A fellow user also alreted me to the fact that sometimes even if everything else is 100% even wiring the ECU pins may not be making contact. so make sure that you check that your using the correct pins if you wired vtec in and make sure they are the correct ecu honda pins and none are opened up at all.
just a last note, i haven't covered ever possible cause in this thread, but im pretty sure 90% of people problems can be fixed or majorly narrowed down by going thru everything i have talked about. I aam always here to try and help people out, but don't post and ask for help if you haven't already tried basically everything here, or you are confused. This thread is based off of information i gathered and read about and is here for you to learn from and help yourself. i can assit but can't fix everyones problems.
Modified by prelittlelude at 2:08 PM 8/8/2006
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04-12-2004, 07:11 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (prelittlelude)
Well, the info i want to add is. If your oil pan is dented pound it out. It took me 3 months of messing and replacing **** before i pounded out the dent in my oil pan and it fixed my problem.
04-12-2004, 07:29 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (CHK4TIX)
thanks for the credit prelittlelude! 
Do not forget that the solenoid itself may be bad, you can test the solenoid. I am not sure the exact procedure, someone made a thread about it not too long ago, but you can listen to it to see if it clicks. Another thing to keep in mind, if you are reving past 6400 rpms, your vtec is working, it is just in limp mode. There are days when my vtec ingages and i can't hear it or feel it. If it does not work, the motor will run the same as an h23, with a redline of 6400 rpms. This does not include fuel cutting off at 5200 rpm's when vtec is suppose to engage. I have no clue why that happens. I have experimented and disconnected my solenoid and oil pressure switch just to see what would happen and it ran exactly like an h23, except with the CEL light on. Maybe one day, we will figure this thing out!
Do not forget that the solenoid itself may be bad, you can test the solenoid. I am not sure the exact procedure, someone made a thread about it not too long ago, but you can listen to it to see if it clicks. Another thing to keep in mind, if you are reving past 6400 rpms, your vtec is working, it is just in limp mode. There are days when my vtec ingages and i can't hear it or feel it. If it does not work, the motor will run the same as an h23, with a redline of 6400 rpms. This does not include fuel cutting off at 5200 rpm's when vtec is suppose to engage. I have no clue why that happens. I have experimented and disconnected my solenoid and oil pressure switch just to see what would happen and it ran exactly like an h23, except with the CEL light on. Maybe one day, we will figure this thing out!
04-12-2004, 01:24 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (jdmlude_dude)
When an H22 is in limp mode it runs no where near an H23a, it's weaker, I've owned both and know how both feel. When in limp mode H22's are weak. That's just to protect them from damage BTW.
Anyway, most info is covered here, I've done a lot of research since I got very little to no help from this site, so it's not needed, but this thread deserves a good bump.
Anyway, most info is covered here, I've done a lot of research since I got very little to no help from this site, so it's not needed, but this thread deserves a good bump.
04-13-2004, 09:53 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
does any body have the color coddes for the vtec solinoid / and the vtec presure switch?
i know you can test the vtec soliniod by taking it out of the car, and supplying 12 volts and grounding the other side, and if it snaps open then its good.
i know you can test the vtec soliniod by taking it out of the car, and supplying 12 volts and grounding the other side, and if it snaps open then its good.
04-13-2004, 08:58 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (prelittlelude)
I know VTEC works off the VSS...what happens if you have a VAFC?
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
04-14-2004, 05:25 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (soopafly828)
that is incorrect. VTEC does not work off the VSS, it works off of your tachometer. When you hit 5200-5400 RPM's VTEC activates, but the VSS does not effect VTEC.
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04-14-2004, 07:24 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
my vtec works its just not strong, it gets loud but but i cant feel the change over like alot of people say they do,,
AEM CAI
Tanabie G power exhaust
DC header
those are the only mods
could i be needing to clean out the VTEC screen thing ive got 81k on my 97
AEM CAI
Tanabie G power exhaust
DC header
those are the only mods
could i be needing to clean out the VTEC screen thing ive got 81k on my 97
04-14-2004, 07:26 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (soopafly828)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soopafly828 »</TD></TR><TR><TD CLASS="quote">I know VTEC works off the VSS...what happens if you have a VAFC?
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
</TD></TR></TABLE>
im not exactly sure about the vafc because i have never used one, but maybe someone else can help out.. the ecu uses the vss to get its speed reference, if you are below the specific speed that vtec is allowed to kick in then it won't work, but i don't know what the vafc does to the ecu or speed signal
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
</TD></TR></TABLE>
im not exactly sure about the vafc because i have never used one, but maybe someone else can help out.. the ecu uses the vss to get its speed reference, if you are below the specific speed that vtec is allowed to kick in then it won't work, but i don't know what the vafc does to the ecu or speed signal
04-14-2004, 08:20 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (prelittlelude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude »</TD></TR><TR><TD CLASS="quote">
im not exactly sure about the vafc because i have never used one, but maybe someone else can help out.. the ecu uses the vss to get its speed reference, if you are below the specific speed that vtec is allowed to kick in then it won't work, but i don't know what the vafc does to the ecu or speed signal</TD></TR></TABLE>
BAHHHH...maybe I'm wrong, but I'm almost positive in my little mind that the VSS does not have THAT MUCH to do with VTEC. My VTEC will engage in first gear...no VAFC or anything...maybe that's just me? But sure enough in 1st gear once I hit 5200-5400 RPMs my VTEC kicks in...And if you are in ANY GEAR once you hit 52-5400 RPMS you are going fast enough for VTEC to kick...so I'm wondering where anyone gets this idea about VTEC running off the VSS...
im not exactly sure about the vafc because i have never used one, but maybe someone else can help out.. the ecu uses the vss to get its speed reference, if you are below the specific speed that vtec is allowed to kick in then it won't work, but i don't know what the vafc does to the ecu or speed signal</TD></TR></TABLE>
BAHHHH...maybe I'm wrong, but I'm almost positive in my little mind that the VSS does not have THAT MUCH to do with VTEC. My VTEC will engage in first gear...no VAFC or anything...maybe that's just me? But sure enough in 1st gear once I hit 5200-5400 RPMs my VTEC kicks in...And if you are in ANY GEAR once you hit 52-5400 RPMS you are going fast enough for VTEC to kick...so I'm wondering where anyone gets this idea about VTEC running off the VSS...
04-14-2004, 09:12 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the_eyecon »</TD></TR><TR><TD CLASS="quote">
BAHHHH...maybe I'm wrong, but I'm almost positive in my little mind that the VSS does not have THAT MUCH to do with VTEC. My VTEC will engage in first gear...no VAFC or anything...maybe that's just me? But sure enough in 1st gear once I hit 5200-5400 RPMs my VTEC kicks in...And if you are in ANY GEAR once you hit 52-5400 RPMS you are going fast enough for VTEC to kick...so I'm wondering where anyone gets this idea about VTEC running off the VSS...</TD></TR></TABLE>
im not 100% sure on the speed, but i belive that car has to be going 17 + mph or it will not ingauge vtec.. its a built in thing so that when your sitting there reving not moving, vtec doesn'r engauge.
BAHHHH...maybe I'm wrong, but I'm almost positive in my little mind that the VSS does not have THAT MUCH to do with VTEC. My VTEC will engage in first gear...no VAFC or anything...maybe that's just me? But sure enough in 1st gear once I hit 5200-5400 RPMs my VTEC kicks in...And if you are in ANY GEAR once you hit 52-5400 RPMS you are going fast enough for VTEC to kick...so I'm wondering where anyone gets this idea about VTEC running off the VSS...</TD></TR></TABLE>
im not 100% sure on the speed, but i belive that car has to be going 17 + mph or it will not ingauge vtec.. its a built in thing so that when your sitting there reving not moving, vtec doesn'r engauge.
04-14-2004, 10:53 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the_eyecon »</TD></TR><TR><TD CLASS="quote">that is incorrect. VTEC does not work off the VSS, it works off of your tachometer. When you hit 5200-5400 RPM's VTEC activates, but the VSS does not effect VTEC.
'Con</TD></TR></TABLE>
No YOU are wrong
The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!
prelittlelude has some awesome info that is 100% correct here so dont think he is wrong or contridict him because you think he is wrong and just are not educated enough!!!!
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soopafly828 »</TD></TR><TR><TD CLASS="quote">I know VTEC works off the VSS...what happens if you have a VAFC?
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
</TD></TR></TABLE>
I think your problem was because the vafc is a hack into your ecu and when you install this and change settings the vafc works mostly off of rpms, and still uses the ecu for the temps. It must get rid of the vss wich would not suprise me at all. Not completly sure here but I beleive that is the case.
'Con</TD></TR></TABLE>
No YOU are wrong
The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!prelittlelude has some awesome info that is 100% correct here so dont think he is wrong or contridict him because you think he is wrong and just are not educated enough!!!!
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by soopafly828 »</TD></TR><TR><TD CLASS="quote">I know VTEC works off the VSS...what happens if you have a VAFC?
because when the part of my differential that moved the VSS went bad VTEC still engaged regardless of the VSS CEL light...
but my question is wat happens when you have a VAFC?
do the same rules apply?
i.e. temp, engine load, oil pressure
</TD></TR></TABLE>
I think your problem was because the vafc is a hack into your ecu and when you install this and change settings the vafc works mostly off of rpms, and still uses the ecu for the temps. It must get rid of the vss wich would not suprise me at all. Not completly sure here but I beleive that is the case.
04-14-2004, 11:04 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (95 lude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95 lude »</TD></TR><TR><TD CLASS="quote">
No YOU are wrong The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!
</TD></TR></TABLE>
man .... so harsh on the N00b, lol ... read an learn my friend, and im not 100% on all my info .. yet hehe
No YOU are wrong
The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!</TD></TR></TABLE>
man .... so harsh on the N00b, lol ... read an learn my friend, and im not 100% on all my info .. yet hehe
04-14-2004, 11:12 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (95 lude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95 lude »</TD></TR><TR><TD CLASS="quote">
No YOU are wrong The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!
</TD></TR></TABLE>
If you want me to pull out my helms I can, but you stated that it works off the VSS from SPEED, not from RPMS. SPEED has nothing to do with it. You want to know why VTEC does not engage when your VSS goes bad? To protect your engine from blowing up. Same when the Oil Pressure sensor and your VTEC soleniod, or knock sensor goes bad, VTEC deactivates so your car DOES NOT run too hard and THROW bearings, RUIN your valve train and DESTROY your valve train. There are a LOT of engine codes that will give you "no VTEC"...so with that i leave you with...
owned.
No YOU are wrong
The vss has a whole lot to do with it because mine just went out and threw a code and now I have no vtec !OWNED BIOTCH!</TD></TR></TABLE>
If you want me to pull out my helms I can, but you stated that it works off the VSS from SPEED, not from RPMS. SPEED has nothing to do with it. You want to know why VTEC does not engage when your VSS goes bad? To protect your engine from blowing up. Same when the Oil Pressure sensor and your VTEC soleniod, or knock sensor goes bad, VTEC deactivates so your car DOES NOT run too hard and THROW bearings, RUIN your valve train and DESTROY your valve train. There are a LOT of engine codes that will give you "no VTEC"...so with that i leave you with...
owned.
04-14-2004, 01:14 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
Blah Blah Blah you have NO clue what you are talking about. 
Vtec is engaged with many different inputs from the ecu and respective sensors!
The VSS just so happends to be one! GOD do you NOT GET IT! I can say if for you as many times as needed if you like!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
Is that enough times for you to get it through your thick scull
God I really hate it when I am right!
The whole reasoning behind the vss and vtec is so that you cant engage it when you and your little riceboys are at a stop light revving the **** out of your motor....hmm get it.... it saves your motor from people like you!
Have a nice day going through your helms trying to prove me wrong! BIOTCH
Vtec is engaged with many different inputs from the ecu and respective sensors!The VSS just so happends to be one! GOD do you NOT GET IT! I can say if for you as many times as needed if you like!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
ONE OF THE SENSORS THAT CONTROLS VTEC ENGAGMENT IS THE VSS!
Is that enough times for you to get it through your thick scull
God I really hate it when I am right!The whole reasoning behind the vss and vtec is so that you cant engage it when you and your little riceboys are at a stop light revving the **** out of your motor....hmm get it.... it saves your motor from people like you!
Have a nice day going through your helms trying to prove me wrong! BIOTCH
04-14-2004, 01:18 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (prelittlelude)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude »</TD></TR><TR><TD CLASS="quote">
man .... so harsh on the N00b, lol ... read an learn my friend, and im not 100% on all my info .. yet hehe</TD></TR></TABLE>
Yeah but close enough. And at least you were nice enought to write this up for everyone that would like to educate themselves.
man .... so harsh on the N00b, lol ... read an learn my friend, and im not 100% on all my info .. yet hehe</TD></TR></TABLE>
Yeah but close enough. And at least you were nice enought to write this up for everyone that would like to educate themselves.
04-14-2004, 01:48 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
now now children, behave, and don't get my thread locked.. and your are both right in some ways
yes speed has to do with vtec engaging
yes when one of the inputs/requirements for vtec is missing the ecu does not allow the secondary cams to engauge because the ecu isn't sure everything is coopasetic.
yes speed has to do with vtec engaging
yes when one of the inputs/requirements for vtec is missing the ecu does not allow the secondary cams to engauge because the ecu isn't sure everything is coopasetic.
04-14-2004, 08:07 PM
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Re: The Official "Why VTEC doesn't Engage" Thread (95 lude)
The first guy stated VTEC WORKS off the VSS, which is not correct. it plays a PART but VTEC does not WORK off the VSS. The VSS simply deterimes if you are moving. VTEC is still engaged by your TACH not your SPEEDO. If youre VSS is COMPLETELY busted and NOT WORKING you won't engage VTEC, HOWEVER, if you are throwing a code, but your VSS is working, then you will still be able to engage VTEC. I know this from experience, I have done 3 swaps on preludes, and much work on them. again I am not saying that the VSS has nothing to do with VTEC, as it has a part, but it does not ENGAGE it, understand? It is activated by your TACH. if you don't believe me, short your TACH test wire, it's a blue wire that should be in a plug on your wire harness, passanger side under the hood, right above the wheel well, connect a ground wire to it, start your car (should now throw a code) and try to get VTEC to engage...yea.
As for your comments 95 lude, if you aren't old enough to handle a debate, please don't respond, I don't have time for children.
As for your comments 95 lude, if you aren't old enough to handle a debate, please don't respond, I don't have time for children.
04-15-2004, 05:27 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
Man you bascially told everyone that I was right. Thanks! I knew it would comeout of you. I knew the whole time that you had it in you. You were just so lost in hte moment that you contridicted your own self without even knowing it.
Just so you dont remember I will quote myself again "one of the sensors that controls vtec is the vss". That my friend is what I was trying to explain to you the whole time. It doesnt matter that the biggest control factor in vtec is the tach(which makes you correct too), it still has to take your speed into play. So if your vss is broken... then vtec is not going to work. Hence that is why the vss is one of the sensors that the ecu takes into consideration before it lets vtec engage.
God I love being right
Just so you dont remember I will quote myself again "one of the sensors that controls vtec is the vss". That my friend is what I was trying to explain to you the whole time. It doesnt matter that the biggest control factor in vtec is the tach(which makes you correct too), it still has to take your speed into play. So if your vss is broken... then vtec is not going to work. Hence that is why the vss is one of the sensors that the ecu takes into consideration before it lets vtec engage.
God I love being right
04-15-2004, 07:37 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (95 lude)
again it does not control its engagement, it is simply a saftey measure. The factors that play into VTEC engagement:
RPMS
Oil Pressure
Knock Sensor
VTEC soleniod
Things that will STOP your VTEC:
VSS Sensor
Low Oil
Cold Engine
Blah Blah Blah
Now, what I am saying is they do not ENGAGE VTEC. They PREVENT it as a saftey measure, but they do NOT engage it. Granted the ECU checks for these, but again it is a saftey measure, Engagement is still controlled by the above factors.
I'm not saying you're wrong, as it does play a part in VTEC working, but not it's engagement. Once on of the saftey measures fails, VTEC is LOCKED, however if they do not FAIL then VTEC is fine and it is engaged by again, the above factors.
RPMS
Oil Pressure
Knock Sensor
VTEC soleniod
Things that will STOP your VTEC:
VSS Sensor
Low Oil
Cold Engine
Blah Blah Blah
Now, what I am saying is they do not ENGAGE VTEC. They PREVENT it as a saftey measure, but they do NOT engage it. Granted the ECU checks for these, but again it is a saftey measure, Engagement is still controlled by the above factors.
I'm not saying you're wrong, as it does play a part in VTEC working, but not it's engagement. Once on of the saftey measures fails, VTEC is LOCKED, however if they do not FAIL then VTEC is fine and it is engaged by again, the above factors.
04-15-2004, 08:18 AM
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Re: The Official "Why VTEC doesn't Engage" Thread (the_eyecon)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by the_eyecon »</TD></TR><TR><TD CLASS="quote">again it does not control its engagement, it is simply a saftey measure. The factors that play into VTEC engagement:
RPMS
Oil Pressure
Knock Sensor
VTEC soleniod
Things that will STOP your VTEC:
VSS Sensor
Low Oil
Cold Engine
Blah Blah Blah
Now, what I am saying is they do not ENGAGE VTEC. They PREVENT it as a saftey measure, but they do NOT engage it. Granted the ECU checks for these, but again it is a saftey measure, Engagement is still controlled by the above factors.
I'm not saying you're wrong, as it does play a part in VTEC working, but not it's engagement. Once on of the saftey measures fails, VTEC is LOCKED, however if they do not FAIL then VTEC is fine and it is engaged by again, the above factors.</TD></TR></TABLE>
its simple, there are many requirements for vtec to engauge, if one of the requirements is not met, it will not engauge. in the end it is the ECU that decideds wether to engague or not, nothing tirggers it, and nothing controls it other than the ECU. i think of all these as requirements, maybe that just me , i do alot of programing and booleen algebra, if all the requirements are ot met that the engineers at honda originally set forth then it simply will not engauge. if you want to look at it as what things will stop it from working that fine. but i know from experience the vss is required , because it feeds the speed reference.
to make it simple one day i was racing a ricer, i shifted to hard, broke the vss mounting tab which in turn poped the vss up out of the tranny, and as i was climing in 3rd gear vtec i watched my speedometer needle fall and after it went below 20 mph and hit 0 i droped out of vtec even though i still had it to the floor.
requirements, just that
RPMS
Oil Pressure
Knock Sensor
VTEC soleniod
Things that will STOP your VTEC:
VSS Sensor
Low Oil
Cold Engine
Blah Blah Blah
Now, what I am saying is they do not ENGAGE VTEC. They PREVENT it as a saftey measure, but they do NOT engage it. Granted the ECU checks for these, but again it is a saftey measure, Engagement is still controlled by the above factors.
I'm not saying you're wrong, as it does play a part in VTEC working, but not it's engagement. Once on of the saftey measures fails, VTEC is LOCKED, however if they do not FAIL then VTEC is fine and it is engaged by again, the above factors.</TD></TR></TABLE>
its simple, there are many requirements for vtec to engauge, if one of the requirements is not met, it will not engauge. in the end it is the ECU that decideds wether to engague or not, nothing tirggers it, and nothing controls it other than the ECU. i think of all these as requirements, maybe that just me , i do alot of programing and booleen algebra, if all the requirements are ot met that the engineers at honda originally set forth then it simply will not engauge. if you want to look at it as what things will stop it from working that fine. but i know from experience the vss is required , because it feeds the speed reference.
to make it simple one day i was racing a ricer, i shifted to hard, broke the vss mounting tab which in turn poped the vss up out of the tranny, and as i was climing in 3rd gear vtec i watched my speedometer needle fall and after it went below 20 mph and hit 0 i droped out of vtec even though i still had it to the floor.
requirements, just that
