ok first off Iam not new to why/how vtec works but am so frustrated at this point Iam hoping someone can help.

car
99 civic ex coupe
built LSVTEC
11.5-1 comp
RM M21 cams
Type r header
Hondata S200 with rywire jumper harness
P72 ecu
440cc RC injectors


ok here is the problem. car has more than enough oil pressure, vss is working, coolant temp is working (all verified in hondalogger) but the car will not hit vtec, checked the map to make sure nothing was set wrong and all is well. datalogging reads everything working fine. I went thru and disabled vtec pressure, still no vtec, got another known good ecu, still no vtec, at this point everything sensor wise on the engine has been changed, tried 2 ecu's, 2 hondatas (s100 and s200), new tps, new map sensor, disabled vtec pressure, ran new wire to vtec solenoid, took the head apart to check for wear/ missing parts.... done it all, we can get vtec to fire off by unplugging the solenoid from the harness and jumping a hot wire to the solenoid (wire right off the battery) but no matter what we do we cant get the ecu to fire vtec, even in hondalogger the vtec pressure light comes on but the vtec spool will not so I know its electrical just dont know where. anybody ever dealt with a issue like this? if so PLEASE HELP!!

 

Get a multimeter and test the output on A4. Look for 12v when it reaches the set vtec RPM..if you dont see it then the ECU isnt sending the signal. If you DO see it then the problem lies somewhere in between.

 

I already know its not sending a signal, have tested with a volt meter and a light bulb. trying to figure out why the ecu just wont fire vtec.

 

anybody?

 

It has to be an issue with hondata if pressure, speed and coolant is good.

 

thats what we thought aswell, but, we even tried other hondata units and still nothing..

 

check your lost motion assembly push it down if it goes up it's good if they stay down change it.

 

im having the exact same problem as well, oil pressure is fine and ive switched out ecu's ive been throwing code 22 since day one, but vtec was working on my p13. then one day it stopped. still had code 22 switched out to a chipped p28 and wired a4 to d6. no codes. but still no vtec?

 

will vtec engage if im free revving the engine? i need to check the voltage from the ecu but tahts kind of hard while driving.

 

see thats just it, I know its not mechanical as I can "hot wire" 12v to the vtec solenoid and fire vtec. its something electrical that wont let the ecu fire vtec and just cant find it..

 

up

 

Just for giggles you should switch out a working known p28.

I dealt with this problem once before, and it turns out one of temperature sensors on the back of the block was not connected.

 

yo was up....look is ur speed sensor working??????????? also is it connected to the oxygen sensor?????????? cause i had dat problem and i fixed it

 

vss (speed sensor,tach,o2 sensor, oil pressure, vtec solenoid, tps, map, ect=coolant sensor) all work fine and we have tried 3 ecu's now with no luck..just plane lost..

 

hmmm maybe your wiring harness is damaged somewhetr causing a short but no code.

 

then try this, use the ecu output for the trigger of a relay and let the relay do the hard work.

 

i got a better idea.

you said it fires vtec when you wire it up manually so insteado of no2 button make it a vtec engagement button, to use at your discretion!

holy **** that would be kind of cool

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Smallpox33 &raquo;</TD></TR><TR><TD CLASS="quote">i got a better idea.

you said it fires vtec when you wire it up manually so insteado of no2 button make it a vtec engagement button, to use at your discretion!

holy **** that would be kind of cool
</TD></TR></TABLE>

then your ecu map will not match unless u can press the button to match the ecu want to activate vtec everytime

 

well, everything on the car has been gone thru. All sensors work like they should, ecu's have all been good and hit vtec in other cars, Iam starting to think a signal from one of the sensors is reaching the cluster but not the ecu but at the same time hondalogger reads fine so I dont know.

 

turns out i had washed my motor and when i did it got water into the breather on the valve cover thinning out my oil which was causing it not to push the pins in to go into vtec.


i hope you get it fixed man.

 

me too, but this is not mechanical as I can fire vtec with a 12v lead, something is not letting the ecu fire it..

 

are you sure its not hitting vtec mybe you just cant here it? good luck finding it.

 

dude u would know vtec on a k20

i still think its wiring harness man. only explanation for it. this is something pretty serious, ive ran into one where they didnt have the distributer at any autozone/advance on my f22b dohc and i had to rip the internals out of an f22a and put them inside the case of the f22b distributer, but then it only worked 180 degrees off, so i had to custom mount the dist upside down

so yeah its gotta be the wiring harness. did you switch out the oil sensor on the back of the block by the oil filter?

 

how high can u rev in this condition,
I mean when ur driving in this situation can u take ur rev till to 8200 rpm,,??

 

with the cams it has in it you know vtec when it hits! and this is in a built LSVTEC not my K20.

I know its electrical somewhere, just cant find it yet.