Unstable engine RPM,

[nitink]

I really wish someone could help me with this I have 95 Maxi GLE, AT with about 107K miles.

In stop & Go traffic the engine surges very rythemically, If I am stopped the engine rpm will be 1000rpm , when I remove my foot from brake (at this time neighter brake not gas is pressed) to move little the engine will surge to 1500 rpm, the car will jerk move forward now engine rpm will come down to 1000. Its like ECU is deliberately increasing rpm.

Car has 4 codes1) p1400 EGRC solenoid2) P17053) Tps code, I forgot the number (TPS is already changed)4) P0325 Knoc sensor

I have already cleaned TB & IACVCan anyone please suggest whats going on, I am pretty scared to drive this car as almost all my commute is in stop & Go traffic.

[maxhopper]

From what you describe, the EGR valve would be my guess. I would also recommend cleaning the MAF sensor with some contact cleaner.

[nitink]

Thanks a lotYou mean EGR Solenoid or EGR Valve it self?

[maxhopper]

Begin with the solenoid itself. Be sure to check for any build up in the lines going to, and coming from the solenoid as well.

In addition, the knock sensor will need to be addressed also.

[hsckris]

any updates ??? everything working fine now ???

[nitink]

Thanks,Today I looked at EGRC for blockage, There are three small vacuum tubes to it and they were all clear. I still sprayed some Carb cleaner to them hoping it would clear off all blocakge. after that When I started the car its still same behavior. so we can rule out blockage in EGRC.

Next I will put in a new EGRC and see if solves problem.

Somehow I am having a feeling that there is a vacuum leak some where, because rpm always jumpes from 1000 to 1500 and comes back to 1000.This is like ECU is deliberately adjusting RPM, but I am not sure why would ecu increase RPM ? and why this condition happens only in stop & go traffic ?

It will take me 2-3 days to get new EGRC, in the mean time if you could think of anything which I should try please let me know.

[Sentientbydesign]

I'm having a similar problem with my 96 I30. Christmas Eve I came back from a family party and dropped off my mother in law. When I went to turn my car back on, the battery was dead.

I jumped it the next day and it ran until I turned it off and wouldn't turn back on. My father in law tried to charge the battery and it wouldn't hold a charge so I went and bought a duralast gold battery from autozone and it works fine, but I'm having idle problems.

I turned it on earlier and it usually idles around 750rmps and it was at 1250 rmps. Later in the day starting it again. It went down to 500 rpms then stuttered a little around 200rpms. I've never had a problem like that before. And the only new addition is a new battery. The old one put out 450 CCAs this one put out 750 CCAs

[nitink]

I cleaned MAF today, MAF connector was slightly loose, I have tighten it and a test run in 5 minutes stop & Go traffic, which comes out fine. I will try in longer stop & go traffic tomorrow.

But I also noticed that when I started my car for the first time, OD light blinked for 16 times !!!

I tried to follow FSM to get code from TCU, but it didn't worked for my car, Any idea how else I can pull out transmission codes? I have OBD2 port, but AFAIK it will not give TCU codes. Is stealership only option to get TCU codes?

[maxhopper]

Directions for checking TCU codes can be found in this thread. zerothread/213507

[nitink]

Today I replaced EGRC valve but the problem is still there.Now only code remaining is for Knoc sensor. which I will take care tomorrow.