sngehl01

Hello all. I recently had someone swap a motor from a 94 z28 to a 97 z28. I'm not sure the motor from the '94 was original to that car, but I believe it was.

The car starts up just fine, but sounds like poo at idle, and it sounds like there may be a miss. It sounds like it is going to nearly die while idling, but doesn't.

I took the car to autozone and it threw a code, something to the effect of "crank sensor misfire" or whatever. However, there is no crank sensor on this motor. What do I do? Would I need to pull the computer from the '94 (which I don't have now, so I'd have the buy the computer) and put it in the '97 to make it work right?

I am not sure if this is related, but it also shifts very hard from park to 1st, and from 1st to 2nd, but then shifts fine afterward. Are the shift points to high/hard, or may there be another issue here?

I can try to provide more info if necessary, but this is all I really know. I'm not really a car guy, but I'm learning.

Thanks!

Z28Camaro30Ann

iTrader: (15)

Are you using a 97 PCM and harness?

sngehl01

as far as I know, yes. I'm not sure how to tell, however.

Z28Camaro30Ann

iTrader: (15)

Ok, that is your problem. The 97 Camaro used an OBD2 computer. It used 4 oxygen sensors, a different knock sensor and it had a crankshaft position sensor. The 94 had none of these. SO, your PCM is looking for the rear O2's which are not there...It is looking for a different signal from the knock sensor, and it is looking for the crank position sensor which is not there.

You need a 94 LT1 PCM for an M6 Camaro. You need the Knock Sensor from a 94 LT1 Camaro and that should fix all your problems!

sngehl01

awesome! I guess I can just pick one up on ebay, or is there someone on the forums I can support?

Z28Camaro30Ann

iTrader: (15)

The CPS is your biggest problem...that will make your engine run like crap and cause a lot of your idle issues. The rear O2's will amplify that and the knock sensor is probably killing your timing because it is getting the wrong signal.

Also you are an auto, my bad. You need to get a PCM for an A4 LT1.

Z28Camaro30Ann

iTrader: (15)

The 94 PCM is plug n play an so is the 94 Knock Sensor. The Sensor is cheap and 94 PCM's arent too much if yo ufind someone on LS1tech or LTXtech or even ebay that has one. I have one for a 94 M6 LT1 but you would have to reflash the chips.

The 94 PCM doesnt even look for the CPS or the rear O2's, so you can actually delete those.

sngehl01

ok, and the knock sensor, what's that all about. Something I need to add or put a new one on? That got thrown in on me and I have no idea what it is, lol.

Thanks for all the help.

Z28Camaro30Ann

iTrader: (15)

The knock sensor is a round sensor that is on the lower passenger side of the block towards the center. It has a plug on it and is just above the oil pan. They are identical in appearance from 94-97 but they emit a different signal. It is easy to install just make sure you do it with the engine cool....it will spill coolant an I learned that the hard way lmao. It screws in and out and is fairly easy to reach. Just take the one for the 97 out, install the one for the 94 in the same spot, plug it in and top off the coolant and you are done with that part.

sngehl01

Awesome, you sir are a fountain of knowledge. Guess I'll order the parts and see what happens. Thanks a lot again! When I end up putting a 383 in my '94 i'm sure i'll have plenty of questions too, lol.

thanks again!

Z28Camaro30Ann

iTrader: (15)

That's what we are here for my friend! Good luck and let us know if you need help with anything else!

RamAir95TA

iTrader: (2)

Ugh...before you go needlessly ordering parts read the following.

The CPS does NOT have any effect on how the engine runs. It's sole purpose is to detect misfires; the PCM does NOT use any input from the sensor to determine fueling/timing. That is actually the LEAST of your concerns. Most people just leave it unplugged and/or block the hole in the timing cover.

Not having the rear O2s will ALSO not cause any idle problem to be amplified. They are only there to report the condition of the cats to the PCM and ensure that they are working. Only the FRONT O2s are used by the PCM for fueling - it could care less what the rears are doing.

You will also need to change some wiring and pinouts to use the 94 PCM. Many things are different between the OBDI and OBDII harnesses so it is recommended you change the wiring harness to whatever year PCM you acquire (to make things simpler). Things like the EVAP circuit and ALDL connector wiring are different - things to consider.

sngehl01

Well now I'm back at a pickle. If I buy the wiring harness for the year pcm I acquire, will I still need to change wiring/pinouts?

Thanks.