Engine Rev

[nash211]

Hi I am new here but I have this problem and I cannot figure this out

The car does as follows, you start the car and it runs normal for a minute then the car`s rpm increases to 2000 then drops down to 800, increases to 3000 then drop downs and continues to do so. It is a constant increase/decrease in RPM. This happens when the car warms up.

We have changed the following on the car. Some may not apply to this case.

A new opti spark accell 3 months old
A new ICM module
A new Map sensor
A new IAC valve
A new PCV valve
New O2 sensors

Today I took off the TPS sensor wire and the rpm stays at 1500 and does not rev, that is the close I got to stabilizing the RPM. Some people say the TPS is a failsafe and that is not my problem. I have tried removing the power booster hose and plugging it with no resolve. If you put the car in gear the rpm jumps up to 2000 and stays there.
We had the computer programed by Mad tuner. Please help

[UDLOSE98]

Re: Engine Rev

what year camaro?

if its a 98 or down, someone might have removed the MAF screen.

[nash211]

Re: Engine Rev

1995 Pontiac Trans Am Lt1 engine 5.7

[woswill]

Re: Engine Rev

My car did this one time after i put gas in it.. i totally freaked.. eventually it stopped

[nash211]

Re: Engine Rev

The throttle blades do not move so It cannot be the TPS, also the car runs fine until it warms up then it begins to surge. It is a temp related issue, can it be the Temp sensors, if not what else is related to temp, that will not throw a code?

[nash211]

Re: Engine Rev

OK, more testing

I unplugged the TPS connection, maintains a idle of 1500 rpm. I then unplugged the IAC while engine running no change to idle. Still maintained idle of 1500. If I plug the IAC back in the rpm surges, the IAC is brand new.


Does anyone have exact instructions on how to reset the IAC. Maybe something we did wrong as per our instructions.

[UDLOSE98]

Re: Engine Rev

might wanna try posting on LS1tech

[4thgenowner]

Re: Engine Rev

My Z did something similar to that. I replaced the throttle position sensor and it went away.

[Scott90]

Re: Engine Rev

vacuum leak sounds like?

[nash211]

Re: Engine Rev

I finally got a code, code 41. Where should I look?

[4thgenowner]

Re: Engine Rev

I searched and found that code 41 is Fault in ignition control timing circuit. It maybe wrong. Please correct me is im wrong.

[nash211]

Re: Engine Rev

It seems we corrected the surging to some extent. Now if the rpm drops down below 1000 rpm the it will surge to 2000 rpm and stay there.

What would cause this?

[nash211]

Re: Engine Rev

I give up, booked a appointment at GM dealer to fix it tomorrow

[nash211]

Re: Engine Rev

I took the car to the local GM dealership, they claimed it was the PCM. I contacted Mad Tuner the people that programmed the PCM and they say the PCM does not have the ability to control the RPM.


Who is right?

The only difference I noticed lately is that the engine backfires through the exhaust, while idling at 2000 rpm. The opti is new but we suspected it may be that, no codes though. Needless to say the car is still not fixed, spent 150.00 to tell me nothing.



nash

[4thgenowner]

Re: Engine Rev

I dunno what the problem could be. But Mad Tuner is full of ****. The IAC valve directly controls idle speed. The computer controls that... I'd say get a PCM from a wreck car and see if that is the problem.