Hi I have a 94T/a A4 with the mod in the sig. Well I recently replaced the O2 sensors because I thought they were they problem. My car starts to jump around on Idleing when the engine is around 180-210 range. It only does it when I am stopped. Sometimes the rpm will jump to 1100 and the car will try moving and i have to put it in Neutral or smash the brake harder. It get very annoying when I am on bumper to bumper traffic. I thought it might have been the O2 sensors but they are new. Both on them. After the search I noticed the IAc got blamed, but why would it do that only on that temp range? . Thank you in advance for any help or suggestions.

 

No body...I am sure I am not the only one with this problem.

 

Surging or hunting can be from a few different problems. My first question is how long has it been since you did a good tune up? The same question for cleaning things such as EGR, MAF, IAC or the throttle body? How long has it been since you cleaned the injectors? I mean really cleaned them not just dumping a can of cleaner in the fuel tank? And last, how old is the opti?

What would be interesting to note is, does the problem start as soon as the PCM goes into closed loop mode.

You should eliminate such items as tune-up pieces. Fuel filter, plugs, wires, TPS, PCV and clean everything mentioned. Then if the problem persists, start monitoring a few things like fuel pressure with a gage and some of the sensor's feedback with a scanner.

It also would not hurt to see if a code is set currently of the type that does not set the SES light.

 

Take the o2 sensors off... see if that fixes the problem. If it does then its a problem in closed loop and most likely a melted wire grounding out.

Get the car on a scanner to test the sensor readings.

Fuel pressure might also be your problem from either the pump or FPR.

Its hard to troubleshoot w/o sensor data.

 

Well the car had a complete tuneup over the summer, right after i bought it. I had the injectors cleaned by the GM dealership. I'll try getting it scanned this weekend and see if anything comes up. Thanx again

 

My car used to do the exact same thing but when i would give it gas it would cutout miss and just run crappy in general. Turned out it was my water pump.... when the car warmed up it would start slowly dripping out of the weep hole right on the opti. changed the pump and ran fine ever since

 

This is pretty common for a lot of us with older LT 1s. I had similar problem. I pulled off the throttle body then pulled the IAC and TPS and thouroghly cleaned all the passages. I then put new IAC and TPS on and new gasket for top plate. There was a whole bunch of carbon clogging everything up pretty good. Car idled and ran 100% better after this. If this does not help check your plugs, wires and opti. Bad O2 sensors wil also cause similar problems. I even heard of the PCM temp sensor in the water pump going bad and causing same systems. Welcome to the "closed loop car running like crap club". This can be aggravating but keep trying eventually you will fix it.

 

i want to make sure I understood your correctly, you cleaned the iac and tps, and then you replaced them??

 

You cannot clean the TPS and you can only clean the pintle end of the IAC. You can clean the TB housing with the IAC removed. Do you have access to a scanner to test the IAC and TPS?

 

The Iac and TPS has to be changed. I just found out they are the original ones and the throttle body has to cleaned. Thanx for all the help.

 

Ok the IAC and TPS wasn't it. And had a friend help me out and do a scan and that didn't help because both of us are out of Ideas? He posted it for in the PCM/Diag section. Here the link
http://web.camaross.com/forums/showthread.php?t=359269

Thank you for all the help in advance.

 

When you said you scanned it, was it just for codes or did you actually view sensor data?

 

It was for sensor data. And then we also did the codes scan. And it said the MAP was bad, and swaped with another working one but it had the same problems. So we are stumped don't know what to do. The link for the sensor logs can me found at
http://web.camaross.com/forums/showt...52#post2995852

Also if you want to see the whole sensor data log, ask fastbird he'll email it to you. Thank you

 

This will seem odd, but I constantly had the same problem in my 94, But it vanished after I installed headers and a new catback

 

Here's a link for the data log if anyone wants to take a look

http://clam.rutgers.edu/~amitr/Amit4_17.uni

Hopefully someone is going to be able to help me out. This is driving me nuts. Thank you all for all the help and suggestions.