My 94 z28 has some strange problems.Let me start from the beginning.When I first got the car I noticed the speed-o-meter was off and the shift points were all screwed up, it shifts to soon.So then I found out that it uses the speed of the car to determine when to shift.So I checked the gear ratio with the code and both were 3.23.That told me that maybe the PCM was from a different car,seems to be programmed for different gears.Now I was going to send the PCM off to have it reprogrammed,but it has other problems too so I figured I have the codes run to see what was popping up before the reprogramm.Now here is my real problem,my machanic ran the codes and damn nere everything popped up EGR,TPS,AC,no timming advance,MAF not reading ect.ect.ect.He said the PCM might be bad the car stays in closed loop all the time.The TPS reading will not move.Basically nothing is reading on his computer, well it reads they just dont move when you rev the throttle they all stay at what they show when he starts his testing.He also said that sometimes when the bulb has been removed from the ses that the codes will not read right I have never heard of this but my car does not have any light in the ses.Has anyone ever heard of this?Why is it staying in closed loop all the time?Could it be a bad computer?I have checked the fuses-all good. I also have a 95 TA could I take the PCM off of that car and put it on the 94 just to check things out before buying a new PCM?Can a dealer test the PCM? I know it has a real problem because it runs sluggish and gets maybe 8 MPG.I know I should put this in the PCM section but I know you LT1 guys can help out just as well.Anyway somebody please lend me some of your knowledge on my prob's I will be greatly thankful.

 

Bump.......

 

Somebody please help me out.

 

The person, maybe before you had it tuned to sty in closed lope.

 

Why would you want to do that?I hope I said it right ,its either closed loop or open loop, which ever one its in when the motor is cold thats what it stays in.The car revs really slow has no power and gets maybe 8 mpg but it purrs like a kitten no missing or rough running just super slow.

 

I'm no expert but from what Ive read I would say mabey the computer is bad or mabey it's a wiring harness problem. You could always get a used computer and have it tuned for your car to see what's up. Ive seen cars stuck in open loop but not closed.

 

Are both the 94 and 95 both obd1.I have an 95 m6 but the 94 Z is an a4.All I need to do is crank it with the 95 PCM just to check it out,does any one know if it will work?

 

Can you get the PCM tested at a dealership?That sounds like an easy way to find out if tthe PCM is bad.

 

yes, don't try the 95 PCM because its a m6. it will throw tranny error codes. The dealer would easily tell you whats up with the car

 

Has anyone ever heard of having any kind of problems after the bulb was removed from the SES?I switched the PCM's and it did run better but still not what it should and yes the trans would not shift right.I then installed the bad 94 on my 95 and it would not rev from idle without missing and it was a little bit sluggish.I did not drive the 95 so I dont know how it really runs.But will it take a little while for the PCM to "learn" the motor or should it pick up right away.I still cant really tell if the PCM is bad or not.What do you think????

 

It shouldnt miss while learning. Idle may be off a little and some other small things while it re-learns but I dont think it should miss. I say just find a way to test your current computer and start rulling out things step by step.