Did a swap on a 96Z with a 94 PCM programmed for a 305 cam and some bolt ons. I swapped the knock sensor also. IS there something I missed? The car im using the PCM on doesnt have everything my car did with the same PCM. I had a 58 MM t.b. and this one is stock. Gears might be different, not positive. Problem is misfiring and bogging. It tripped a SES light a few times, but not everytime, and when you key off, the light goes out, so its not a hard code. I wondering if I missed something in the swap or if its opti related as someone "resealed" the opti when the swap happened. The car doesnt like higher rpm's, it feels like its retarding the timing hardcore, and then if I let off because the car wont accelerate, it backfires from loading up. It idles fine and free revs great minus a little stumble at idle. Problem mostly occurs when trying to get on it quickly instead of gradually. Im wondering if the tune could be off fromthe lack of all the bolt ons I had that this vehicle doesnt, or if its something else. I need to scan the vehicle to see what the code was, how do I go about that now since its an OBD2 connector with and OBD1 pcm? Do I tell it its a 95 and use the OBD2 connector or do I need to convert it to a GM1 connector and scan it as a 94? The PCM was originally a 94. One more thing, the crank sensor in the timing cover,.....should that be plugged in with this setup or should I unplug it (since a '94 didnt have this).

 

The lack of a 58mm TB and other mods (which the PCM is programmed for) could be the cause of your problems. You should flash the PCM with an appropriate tune for the current set-up and try it before looking any further.

First off, my car has and OBDI coversion PCM... it's converted internally, so I'm using the OBDII knock sensor.

You're right about treating the car (for scanning purposes) like a '95 - factory equipped with OBDI PCM and OBDII diagnostic port. As for the crank position sensor... it is strictly for missfire detection, which OBDI doesn't have, so it is not used in your case. But to be honest, I don't know if mine is actually plugged in or not - I didn't install the motor.

 

One more sidenote I remebered,.....his car has pacesetter LT's and didnt come with O2 extensions but rather a length of wire and butt connectors. I didnt like that idea but its all I had at the moment and I had to get the car back together and running so I used them. I cut into the O2 side of the connectors so as not to destroy the main harness. Im now looking back wondering if that was a very good idea. I know the O2's were wired back together correctly but im wondering of the reliability of butt connectors and if they'll cause any type of issue with correct O2 readings? Ill try scanning it today but im just thinking out loud. Also im not positive of the EVAP hoses and solenoids routing(stuff on the passenger side of the manifold). I know the solenoid itself correct I believe but the other one next to it on a '96 could possibly be upside down and essentially hooked up backwards. Its the one that goes uder the t.b. to the fuel harness. It has 2 fittings and a little ruber boot (elbow) that doesnt go anywhere as of now. Im not sure if anything hooks into that or if it vents to atmospphere. I have the rubber elbow facing upward now. If anyone has a pic of that it might help. Its broke where it mounts to the bracket and I cant tell which way it was on the bracket now. Other than these issues, ive double checked all my work and wiring for burns on headers etc. and everything looks good. Thanks for any help.

 

ok, did some more diag. today and got into the pcm. I retrieved codes 26 and 16. 26 is quad driver, something about EVAP solenoid on Alldata. This was probably from running the car without the solenoid plugged in. 16 is a loss of low res. signal. This one kinda scares me. AFter messing around driving some I found that it only has this driveability issue in closed loop. Open loop the vehicle works great and pulls hard all the way to redline. Once she heats up and hits closed loop,......misfires, backfires, seems like spark or fuel cutout. This happens mostly about the 2500 rpm range and getting into the throttle quickly. She'll just cut out, the car seems like its not running, the pedal has no effect while its doing this, then when the engine slows to like 2000 rpm, its like it picks back up and is running again. Sometimes this is when I get the big backfire like the cylinders were loading up while it wasnt firing. I did get an O2 sensor lean code 64 once but I cleared it and it didnt come back. I also got a code 42 but only once and that too was cleared and did not come back. Its something to do with the IC module wiring, saying its grounded or shorted to power. Upon further reading Alldata it seems if this code pops it will cut fuel pump and injector duty, which is where it seems im at, but that code only came up once and ive repeatedly duplicated this issue at least a dozen times tonight trying to nail down this problem. The only thing I can think at this point is the opti ext. wire where it plugs into the opti is busted up some but the pins are in good cond. and like I said, in open loop this thing runs great so I dont think thats the problem. One other thing that popped into my head today was that crank sensor plug (vehicle was a 96) is somehow backfeeding the PCM and messing it up, maybe I should just disconnect it since its not used for 94 OBD1 anyways.

One last thing, does anybody definitely know what sensors need to be swapped for this conversion? So far ive only been told the knock sensor and I did that. I do see about 8* of knock at times while trying to get on it hard. I dont think thats enough to make her backfire and cutout. Anybody know if I need to change O2's maybe or MAF, MAP, etc etc.? SOMEBODY HELP!!!!!

 

As I understand it, the knock sensor is the only sensor that needs to be swapped. The OBDI PCM will ignore the crank position sensor and the rear O2s. The MAF, MAP, etc. are all the same. Checking in the Camaro parts book, the '94-'97s use the same MAF, MAP, and (front) O2s.

My OBDI conversion PCM is internally modified to work with the OBDII-spec knock sensor. All the other sensors in my car are original (or original replacements).

8* of knock retard shouldn't make your car act the way that it is. I've seen almost that much with my car from time to time, and the car still ran well.

 

For those of you who were interested I conquered this b!tch tonight. After thinking back on how it went down, the cooling system had an air pocket and when I went around the block (only twice) it overheated. Right about the same time is when I recalled the engine misfiring began. I looked into the few codes I gathered, even though I erased them and they did NOT return. I found the code 42 to be the best clue as to what had happened. The diag procedure and actions taken when PCM detects this issue were a little misleading but I never follow the proceedures without thinking them through first, because I have concluded PCM's b4 and been wrong after following the flow charts. Long story short,..... the code was for coil module control circuit shorted to power or ground. I knew this probably wasn't possible so I thought back and realized that the ciol module doesnt like heat, much less extreme heat such as overheating being that its on the head. Basically, it was shorted internally and the PCM was detecting the wrong voltages on the control circuit thus disabling the fuel pump and injectors, causing my loss of fuel and bogging after 2500 RPM. The actions taken when PCM see this code were exactly that which lead me to investigate this code vs. the others. This code caused the lack of spark which caused the PCM to disable the fuel supply to prevent the engine from being flooded. Crazy ****, huh? The car runs strong now and the customer was happy as a pig in ****. Time to get paid!