Ok...here's the run-down.

A customer brought his '91 Civic with a B16A swap into our shop...the "installers" did a complete hack job on the wiring harness and everything was heading down the crapper quick. So, we pulled a wiring harness out of a '92 Civic and ran 2 separate harnesses (1 for the engine, 1 for everything else). The harness is in and everything is pinned correctly (so we think), but VTEC still won't engage.

At first we thought it was an ECU issue, so we took the ECU out of my GSR'd '94 Civic and plugged it into the '91...VTEC engages properly. We then took the B16A ECU and plugged it into my GSR'd Civic and what do you know...VTEC works. But whenever the B16A ECU is plugged into the '91 Civic with the B16A, VTEC will not work.


Help?

 

Check light on ?

your chipped ecu might be a one wire vtec setup.. Knock and oil pressure diabled?

I bet the stock b16a ecu is looking for vtec oil pressure.. or knock? Just a guess.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote"> Check light on ?

your chipped ecu might be a one wire vtec setup.. Knock and oil pressure diabled?

I bet the stock b16a ecu is looking for vtec oil pressure.. or knock? Just a guess. </TD></TR></TABLE>

No check engine lights.

Neither of the ECU's are chipped.

We scanned the B16 ECU and it threw a vehicle speed sensor code and a knock sensor code.....

But VTEC SHOULD, hypothetically, be working


However, we've plugged the B16 ecu into my GSR twice...the 1st time VTEC didn't work and it threw a VTEC solenoid code...there was a loose wire, so we fixed that and voila...VTEC works now.

 

a knock code will disable vtec. your gsr motor must have a knock.. that is working.. that is why the ecus work in that car.

Add a knock sensor... or chip the ecu..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote"> a knock code will disable vtec. your gsr motor must have a knock.. that is working.. that is why the ecus work in that car.

Add a knock sensor... or chip the ecu.. </TD></TR></TABLE>

We just went out and ran the B16 ecu in my GSR again...my GSR has no knock sensor (obd1), but after a while of running it hard with VTEC the check engine light came on.

So we're about to go run it again and SUPPOSEDLY VTEC should stop working because of the knock sensor.

One idea that has crossed our minds is that the speed sensor may have something to do with it...the vehicle may not even realize that it's in motion when it really is..and another thing is that the knock sensor is a 2 wire set-up, but the '92 harness only had one wire for it so we assumed that the other wire was for a ground...so we still have some more investigating to do.

Thanks for the help and we're open to all ideas

 

once vtec in on it monitors the knock volts... if no knock detected.. it will trip a CEL for code 23 Knock and shut vtec off. Once you reset the ecu.. process starts over.

All honda knock senors are one wire. I would guess you have the wrong plug on your b16 knock sensor.

Also. Your OBD1 gsr DOES have a knock or is suppose to. The speed sensor will also mess up vtec .. becuase you suppose to be going at least (X) amount of speed before vtec and (X) amount of tps before vtec will fire.. That is how it works on BONE stock ecu's

get a ecu pinout of your ecu and run the wires direct.. Knock has no ground.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote"> once vtec in on it monitors the knock volts... if no knock detected.. it will trip a CEL for code 23 Knock and shut vtec off. Once you reset the ecu.. process starts over.
All honda knock senors are one wire. I would guess you have the wrong plug on your b16 knock sensor.

Also. Your OBD1 gsr DOES have a knock or is suppose to. The speed sensor will also mess up vtec .. becuase you suppose to be going at least (X) amount of speed before vtec and (X) amount of tps before vtec will fire.. That is how it works on BONE stock ecu's

get a ecu pinout of your ecu and run the wires direct.. Knock has no ground.
</TD></TR></TABLE>

My ECU may be chipped (no rev limiter), but the guy I bought the wrecked car from that had the GSR in it had EVERYTHING half-assed, so I'm getting a new Hondata ECU this summer because the current one won't even allow you to scan.

And as far as I know...OBD1 GSR's don't have knock sensors. Could be wrong though...

 

All DOHC vtec engines have a knock sensor.

To check the "codes" on a obd1 ecu.. all you have to do in ground a selected pin.

USE THIS LINK TO WIRE YOUR CAR CORRECTLY.
http://tech2.hybridgarage.com/..._obd1

D3 - Knock

A13- Ground to ground. Count the check light blinks on the dash. = "code" No need for a new ecu.

Run the wires correctly or Send the ecu off to get chipped for 1 wire vtec. (disables all the sensors for vtec)

No rev limit = chipped Change the chip or get hondata s300

I hope this helps..

 

actually, your problem lies within the VSS. you need the vss to be working for vtec to work.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pennies_hatchie &raquo;</TD></TR><TR><TD CLASS="quote">actually, your problem lies within the VSS. you need the vss to be working for vtec to work. </TD></TR></TABLE>

Yeeeeeep...that's it. We unplugged the VSS on my GSR'd Civic with the B16A ECU and VTEC did not engage. So either he's going to send his ECU off to get a chip put in or he's going to swap with me and I'll run the B16A in my car until I get my Hondata ECU. Good call dude.


OBD1 GSR's DO NOT have knock sensors.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JKov240 &raquo;</TD></TR><TR><TD CLASS="quote">

Yeeeeeep...that's it. We unplugged the VSS on my GSR'd Civic with the B16A ECU and VTEC did not engage. So either he's going to send his ECU off to get a chip put in or he's going to swap with me and I'll run the B16A in my car until I get my Hondata ECU. Good call dude.


OBD1 GSR's DO NOT have knock sensors. </TD></TR></TABLE>

GSR motors have a factory knock sensor ... *** hat. Look around before you claim a fact you know nothing about. If you would have looked at the link.. you would have had a better idea.

Hard headed.

4 things the ecu looks for before it will fire vtec on a factory obd 1 dohc vtec ecu.

knock sensor. (knock only montiors during vtec engagement) ***
Vss sensor (makes sure you moving b4 vtec fires)
vtec oil pressure (makes sure you have oil to make vtec function)
vtec solinoid ( lets the oil in the head for mad vtak)

Dont state facts about things you are not postive about.


NOTICE : The Green One Wire plug. Knock sensor plugs in there.


Modified by havok hybrid at 12:40 PM 2/22/2007

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote">a knock code will disable vtec. your gsr motor must have a knock.. that is working.. that is why the ecus work in that car.

Add a knock sensor... or chip the ecu.. </TD></TR></TABLE>


FALSE...a knock code will NOT disable vtec, but a VSS code will disable VTEC since VTEC needs a speedo reading in order to operate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote">

GSR motors have a factory knock sensor ... *** hat. Look around before you claim a fact you know nothing about. If you would have looked at the link.. you would have had a better idea.

Hard headed.

4 things the ecu looks for before it will fire vtec on a factory obd 1 dohc vtec ecu.

knock sensor. (knock only montiors during vtec engagement) ***
Vss sensor (makes sure you moving b4 vtec fires)
vtec oil pressure (makes sure you have oil to make vtec function)
vtec solinoid ( lets the oil in the head for mad vtak)

Dont state facts about things you are not postive about.
</TD></TR></TABLE>

Again, you're wrong.

The VTEC engagement needs these sensors hooked up in order to work properly:

1) coolant temp
2) VSS
3) VTPS
4) VTS

The knock sensor doesn't disable vtec.

not to be a dick but your statement has a hint of irony:

"Dont state facts about things you are not postive about. "


PS for the masses: All DOHC VTEC engines have a knock sensor


JKov240,
I'm gonna make an educated guess and say the problem lies in your wire harness somewhere being that you swapped that out. With EF civic/crx swaps, especially Si models, it's best to reuse the Si harness and adapt the OBD1 dizzy plug and 4-wire 02 sensor, then of course run a EF to OBD1 jumper harness adaptor, instead of trying to combine the EF and OBD1 engine harnesses......no need for doing this; makes things complicated and chaotic.

If the EF is a Dual-point injection model...yikes...I have nothing to say as those are a nightmare when it comes to wiring...

 

ok take your knock sensor off any tell me your vtec still works.. *** .

Once vtec is on.. ecu looks at the knock to see what is happening in the High RPMS....

It will fire vtec BUT if no knock is detected .. it will then shut down vtec and CEL 23 will come on. .. try it out smart ***..

 

The problem was with the Vehicle Speed Sensor...

On earlier Civics, it has a speed sensor built into the back of the speedometer head (the speed sensor is right on the transmission on EGs, etc.) , so we used that to run to the ECU and it worked right.

 

As for the knock sensor (we did the swap a couple months back in my car) and neither me (or my dad) remember wiring in a knock sensor (we used a '94 Civic Non-VTEC wiring harness)...and all that we wired in was the VTEC solenoid, oil pressure switch, and IAB.

So...

A) we didn't wire it in (my ECU was half-assed by the previous owner and won't allow us to scan and it won't throw CEL's)

or

B) it was already wired in and we plugged it in and forgot

I'd like to apologize to havok hybrid...I was going off what we wired in.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by havok hybrid &raquo;</TD></TR><TR><TD CLASS="quote">ok take your knock sensor off any tell me your vtec still works.. *** .

Once vtec is on.. ecu looks at the knock to see what is happening in the High RPMS....

It will fire vtec BUT if no knock is detected .. it will then shut down vtec and CEL 23 will come on. .. try it out smart ***.. </TD></TR></TABLE>

Calm down.
I'm not being a smart ***, I speak from experience. Besides this tidbit, your other info is correct

The KS will not 'shut down' VTEC from operating, but it will retard the timing if the KS CEL is thrown.

JKov240,
Glad to hear you figured out it was your VSS. If you run a reprogrammed P28 ecu with disabled KS, you'll be good to go now

 

I was at school while my dad was working on it, but I got to the shop and he said he figured it out and it was something to do with the vehicle speed sensor being behind the speedometer head and that the ECU was still looking for that signal from behind the speedometer...so he hooked the original '91 wire up to the ECU and voila...it worked.

 

I just looked at Alldata and a GS-R calls for a knock sensor. I also looked up a '94 Civic VTEC and non-VTEC and neither of those called for a knock sensor.

Soooo I dunno...I'll put it up on the lift later and look from the bottom

 

Katman is correct the knock sensor code doesn't disable VTEC operation. Check here for any problem's with VTEC not working, its a FAQ I made for OBD0/1/2

https://honda-tech.com/zerothread?id=1812135

 

Remember how I said everything about the car/swap and the previous owner was half-assed? Yeah...the harness was too.

The owner took it to a Dodge dealership of all places to get it done.

Instead of using a GSR harness they used the EX harness and just kinda connected stuff that "looked right". MY motor never had a knock sensor (has a place for it, but never had one), and was never wired for one...so I can only assume that the ECU we can't scan is "chipped" to not even read for a knock sensor.

 

ah sorry to hear this..
hopefully you'll fix the other guys mistakes

 

We finished it last Thursday (I think) and haven't heard from the customer yet...so I guess that's a good thing