Hi everyone I am new to the forum, Name is Chris.

This is my first post so I figured I would make it good at least.

I rebuilt the engine, transmission, brake system on my 1987 Camaro Iroc Z.

The engine. 5.0 ltr TPI.
What I have done to fix the problem:

Tried most of the solutions in this forum, IAC adjustment, TPS adjustment etc etc. The solutions works (Or seams to) But as soon as the car cools down it goes right back to 1500 RPM's. Everything torqued according to the Factory Service Manual (Actual FSM not Autoparts manual) but the idle will not stay.

The car runs great, has lots of power, shifts perfect but I can't seem to track down that idle problem. Timing was set according to manual, voltage for tps set at .54, Checked the entire intake for leaks (FI Cleaner) nothing. Another thing it does is at an idle its not smooth it has kinda a lopy? feel but the cam is stock. Idle screw was adjusted to about 450 - 500 with IAC disconnected.

Injectors are brand new, No misfire, I do know a lot about cars but this one has me confused. All smog devices attached and appear to be functioning since it passed smog very well.

Anything I can try? Test?

PS: I do have a factory service manual and I can copy pages for people if needed.. Just let me know what you need from it.. Its for a 1987 Camaro.

 

Have you pulled the engine error codes to see if anything showing?
see
https://www.thirdgen.org/forums/tech...s-dumbies.html

A bad sensor ( or it's wiring ) can give a wrong input to the ECM
If for example ,the ECM is getting a indication the engine is colder than what it actually is then it will be giving the wrong outputs .

Look for a code 14 or 15 (CTS fault )

Be aware
a error code is for a system fault SOMEWHERE ;not that the sensor on a circuit is actually faulty
There may be a problem with the power , the grounds or the system wiring

Work through the diagnostics below before throwing $$$ at it
http://chevythunder.com/cts_diagnostics.htm
http://chevythunder.com/cts_diagnostic_pg2.htm

Or connect a scanner and see what the CTS ( coolant temp sensor ) is reading in relation to the dash temp gauge.

 

No CEL on. Do the codes show up when there is no CEL? I do have two computers both from an 87 Iroc Z, I had picked one up as a parts car for the engine harness and a couple of other misc pieces.

But would a faulty CTS cause that high of an idle?

Thanks for the response.

 

Wait.... Dumbies?

I do believe I have gotten the hang of that one.

 

Does the SES work, key on?
Worth pulling the codes anyway

Possibly
All of the ECM calcs are based on getting the correct engine temp indicated

https://www.thirdgen.org/forums/tpi/...-question.html

 

Yeah it works, I just replaced the printed circuit on the back and replaced all the bulbs. So seat belt and CEL come on with key on.

I will check that sensor tomorrow thanks for the info.

 

Ok so I checked all my connections, Found a ground off on the back of the engine from the harness. Also found another plug that was burnt against the exhaust manifold. Took car of both not sure what the random plug is for yet.

Codes popped up..

33 Mass Air Flow sensor High GM/Sec Indicated
22 Throttle Position sensor signal voltage low
36 Maf Sensor Burn Off Function Fault
34 Vehicle Speed Sensor

As for the TPS (22) I am assuming that since the engine idle is too high at the given value it is causing this?

Maybe the Mas 33 is because of the same thing?

34 I am thinking is also due to the High RPM?

So that just leaves 36 would 36 cause this problem? But I am open to suggestions at this point. I will be checking all the codes according to the FSM flow charts. Hopefully I get some some success out of all of this. No codes for the CTS though.

Could all of this be caused by a ground wire off from the engine harness?

 

I let it run for a little bit and now it seems to idle right, All CEL are cleared and stayed off. I am assuming that the ground that was left lose grounded the relay's to run a few things.

I will start it up tomorrow when its cold and check to see if it worked.