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Poor running on VTEC ECU after h22a conversion FIXED!

Posted: Fri May 19, 2017 9:55 am
by JEBB4
So as some may know I've done a h22a engine conversion on my bb2 (h23a1 non VTEC) and I'm having some issues..

The car runs spot on and pulls well but smokes badly on the p14 (h23a1) ECU also get oxygen sensor fault code as expected..
When putting the p13 ECU in the car idles fine but is very under powered and jerks and hesitates under partial load or cruiseing..

Getting faults for:
VTEC solenoid (expected)
Oxygen sensor heater
Knock sensor

(I understand that my car is not wired for VTEC but wasn't expecting it to run so bad on the ECU that's correct for the h22...)

So I swapped the oxygen sensor tonight, the old one had completely broken off so was hopeful of a fix but no good..

So the only thing I can think of is that the knock sensor fault is the cause but I don't understand how it runs so good on the other ECU as that has a knock sensor as well and I'm sure they both go to same pin on the ECU??

I'm certain the car should run fine without VTEC wiring and unless the two ECU's have different pins for knock sensor I can't understand why it's so bad..

If anyone knows if the knock sensor pins are somehow different on the two ECU's or has done a VTEC swap and has experience with this would be a massive help :|

Also if anyone has a reliable source for ECU pin outs for 4g prelude ECU's would be great..

I'm hoping to try wire up VTEC solenoid and figure out the knock sensor tomorrow but if someone can point me in the right direction of some reliable pin out info I'd be very appeciative :)

EDIT: could the knock sensor wires be in different locations at the shock tower connectors where engine loom plugs into chassis/dash loom?? I'm using the h22a engine loom plugged into the h23a1 chassis/dash loom by the way.. :think:

Posted: Sun May 21, 2017 6:42 am
by JEBB4
Update on this...

I have now gone through the loom and wired in both oxygen sensor heater wires, knock sensor, logic ground 2, VTEC pressure switch and VTEC solenoid..

Using this pin out data
http://technet.ff-squad.com/wiring.obd1.htm

Now I have no fault codes/CEL with the P13 ECU but it's not revving out, popping out the intake and feels basically like VTEC is stuck engaged..

If I swap to p14 ECU it runs and revs as it should with no fault codes/CEL at all!!

Faulty ECU?

Re: Poor running on VTEC ECU after h22a conversion

Posted: Sun May 21, 2017 7:52 am
by hondaddict
Sorry to read that, mate :(

Could you post a picture of the Inside of the P13 ECU ?

If your engine runs normally with the P14 ECU, yes it could be an ECU problem :|

Posted: Sun May 21, 2017 9:55 am
by Thebusofwoe
Well look at it this way. You have now eliminated any faults with engine, sensors and wiring by having the p14 ECU run as it should. So it can only be a faulty p13 ECU or chip. ;)

Posted: Tue May 23, 2017 9:43 am
by JEBB4
I fixed this issue tonight..

If anyone tells you h23 injectors are the same as h22 slap them with a wet fish! :lol:

Swapped the injectors to the h22 ones and she's all good, the h23 injectors are smaller Hense why it would run fine on the h23 ECU but must have been running lean as, then there just wasn't enough fuel to rev on the h22 ECU..

Well I'm glad that's fixed I will hopefully do a swap guide on the whole convertion at some point so that people do not experience the same ball aches I have..

Re: Poor running on VTEC ECU after h22a conversion FIXED!

Posted: Tue May 23, 2017 5:46 pm
by hondaddict
Happy to read that you've fixed the problem :D

The 4th gen H22 injectors are 345cc if i remember correctly and the H23 injectors are 240cc only, so there's a big difference between them... ;)

I was believing that you were using the H22 injectors, it seems that the informations you have for the swap are not really accurate... :oops: