CRX B16A

[Tim@Canspeed.com]

Looking for some help.

We're dealing with a 91 CRX w/B16A run by a PR3.

The problem is we are hitting rev limit at 7200RPM. (It is my understanding that the PR3 has an 8200rpm limit).

Here's the twist. We take a PR3 from another car here at the shop that runs a rev limit of 8200RPM. (We check this to make sure, yup 8200RPM!). We put this PR3 into the CRX and it hits 7200RPM limit.

So what we have is: No matter what ECU we run in this CRX it will always cut off at 7200RPM.

First question: What sensors may affect the rev limit in this vintage of OBD.
Second question: What the hell is going on?

Any help is appreciated.

 

[B16RacerN2NR]

are you throwing any CEL? codes 8 (TDC) and 17 (Speed Sensor) will let you rev that far (7200) but vtec will not activate so it (fuel) cuts off around 7200-7600RPM

 

[Citizen_Insane]

yeah, it has to be throwing some code. The engine is in limp home mode (which is why the rev limit is lowered).

 

[Tim@Canspeed.com]

So is the rev limit for the PR3 8200rpm?

Only code thrown is VTEC. VTEC activation is not hooked into the computer (An SMT6 is looking after VTEC control). The VTEC oil pressure input is hooked to the computer however.

Is it possible that a sensor is affecting the rev limit? ie: engine coolant sensor, etc.

 

[Citizen_Insane]

Originally posted by Tim@Canspeed.com@Jun 19 2004, 02:05 PM
So is the rev limit for the PR3 8200rpm?

Only code thrown is VTEC. VTEC activation is not hooked into the computer (An SMT6 is looking after VTEC control). The VTEC oil pressure input is hooked to the computer however.

Is it possible that a sensor is affecting the rev limit? ie: engine coolant sensor, etc.

Yes the PR3 and PW0 ECU's have a rev limit of 8200 rpm. The reason this can't be reached on your car is because you are throwing codes. IF there are codes, performance is retarded. Plain and simple. Wire up the VTEC and you'll be fine B)

 

[Tim@Canspeed.com]

The problem with that is, the car we pulled the other ECU from (that does rev up to 8200rpm) doesn't have the vtec hooked up either. The vtec is hooked to an external controller (SMT6). When I put this ECU into the CRX it only revs to 7200rpm.

 

[lvbuckeye]

HOOK UP YOUR VTEC! to the ECU, not some external controller... if the ECU doesn't 'see' the VTEC, then how TF is it supposed to know it's there? your rev limit is directly related to the ECU 'thinking' that VTEC is not hooked up... i.e. get rid of that SMT6...

if you want to mess w/ VTEC engagement, get an Apex-i VAFC-II, or better yet, get a Hondata...

 

[B16RacerN2NR]

Originally posted by Tim@Canspeed.com@Jun 21 2004, 12:03 AM
The problem with that is, the car we pulled the other ECU from (that does rev up to 8200rpm) doesn't have the vtec hooked up either. The vtec is hooked to an external controller (SMT6). When I put this ECU into the CRX it only revs to 7200rpm.

Every car is different. TRUST ME!!

 

[Tim@Canspeed.com]

Originally posted by lvbuckeye@Jun 22 2004, 04:59 AM
HOOK UP YOUR VTEC! to the ECU, not some external controller... if the ECU doesn't 'see' the VTEC, then how TF is it supposed to know it's there? your rev limit is directly related to the ECU 'thinking' that VTEC is not hooked up... i.e. get rid of that SMT6...

if you want to mess w/ VTEC engagement, get an Apex-i VAFC-II, or better yet, get a Hondata...

So how is it possible that an APEX-i can be hooked up to control vtec and won't affect the rev limit but an SMT6 will?

Anyone else have any thoeries without holes? (honestly, I appreciate the help. But your logic just doesn't add up)

The car from which we take the ecu with the rev limit of 8400rpm has the vtec hooked up identically to that of the CRX that, with the ecu we just removed from the working car, only revs to 7200rpm.

The vtec oil pressure sensor, in both cars, is hooked to the ecu. (This is the sensor which, if does not detect oil pressure will not allow vtec to engage) The only thing not hooked to the ecu is the vtec activation wire.

P.S. hooked the activation switch to the ecu and still 7200rpm.

 

[Tokay]

Sounds like a bad knock sensor. vtec won't engage with out one. Disconnect it. Ground a second knock sensor from your other motor and run a jumper wire to the PR3 ecu that your using. Fire it up. If that works get a new knock sensor. Make sure you have oil too. B)

 

[Tim@Canspeed.com]

Thnx. I'll check it out.

 

[krazie1]

Has anyone thought maybe it could be that he has a Automatic ECU
only auto ecu's kick rev limiter at these rpm's??????

that is if u haven't found the problem yet....

 

[brian11to1]

Originally posted by krazie1@Jul 3 2004, 12:01 PM
Has anyone thought maybe it could be that he has a Automatic ECU
only auto ecu's kick rev limiter at these rpm's??????

that is if u haven't found the problem yet....

good thought. but hey pulled an ECU from another B16 powered car and had hte same problem.