RE: 1997 A4 1.8T Quattro rough idle problem
 

yeah it runsreall strong USUALLYafter that 2-3 minutes of initial idleing

RE: 1997 A4 1.8T Quattro rough idle problem
 

A commom cause of that problem is a failed coolant temp sensor. It can cause rough starts when the car is cold, just another one of the many possibilities that could be causing you grief.

I said coilpacks since you are getting the misfire codes. Have you cleard them to see if they come back or not, and verified they are the same codes? That would help troubleshoot.

I saw you had another thread......maybe I'll copy this post over to there.

RE: 1997 A4 1.8T Quattro rough idle problem
 

Got my new ICM today. I tried the resistance test on it and same thing, no reading. I did find another test on the net though here:
http://www.automotivehelper.com/topic215530.htm
Scroll down to 2nd to last post by donbuska. According to his instructions you don't need a battery, you just touch the positive (red) dmmlead to the middle pin on the 5-pin side, and touch the negative lead to each pin on the 4 pin side. He also says to set the resistance to the highest range. He got readings of 2.3-2.6 Mohms. When I tried this test I set my dmm range on the 2Mohms range. When I touch the leads it flashes a reading of around 1.9Mohms for a split second then shows a steady 1. I tried a different dmm and it didn't flash any value, just read 1. So then I tried the diode mode, if I touch the red probe to a pin on the 5-pin side and the black probe to the pin directly across from it, I get a reading of 0.650 for each pair of probes. That means it's not open right? Anyways, I'm pretty sure now that the problem is not the ICM.

I did clean the throttle body a few days ago, and after I got and tested my ICM today I cleared the DTCs with vag-com, ran the throttle-body adaptation, then started the car. It runs a little better. Can still feel misfires but they don't seem to be as bad. I believe the throttle-body cleaning helped improve the idle and performance while driving, but I'm still getting random multiple cylinder misfires on all 4 cylinders. Any ideas on what else this problem could be caused by? Thinking about unplugging the MAF tomorrow and driving the car a bit to see if that does anything.

RE: 1997 A4 1.8T Quattro rough idle problem
 

Tried unplugging the MAF, clearing themisfire codes,and then driving around a bit today, but still misfires. Vagged it once I got back and there was a MAF weak signal code (expected) and same multiple cylinder misfire codes. I picked up some MAF cleaner spray regardlessand sprayed the crap out of the MAF and its connector pins. Let it dry, put it back in, cleared the codes and drove around some more, still misfires, vagged it when I got back and still random/multiple cylinder misfire codes, and misfires on cyls 2 and 4. Probably just need to drive a bit more for cyls 1 and 3 misfiresto show up as well. Oh and I also picked upa bottle offuel system cleaner and put that in with a full tank of premium gas. No noticeable effects from that yet I guess. Ok so far I have:
1. Tried 2 new ICM's (Bosch and Huco)
2. New ECU (8D0 907 557 P)
3. New NGK BKR6E copper spark plugs (gapped .032, torqued to 22ft-lbs)
4. Cleaned throttle body
5. Cleaned MAF with MAF sensor spray
I think that's all so far. Let me know what I should try next. Keep in mind the car wasn't misfiring before the turbo blew, it was running good. Then the turbo blew and there was "excessive shaft play." New turbo and oil pumpput in by a localaudi/porsche mechanic. He said there was lots of oil sludge, so I believe he flushed the engine, got it all cleaned out and put in a new fuel filter. So after all that it's been idling rough and I still don't know what's wrong. So any ideas what I should try next? Thanks again for the help.

RE: 1997 A4 1.8T Quattro rough idle problem
 

Wow, tough problem.

Misfire can be caused by:
cracked plug, icm, wires between icm and coils, coil packs, clogged injector, leak in headgasket.

Since it is in multiple, that makes it harder. You may want to try to replace all 4 coils. Also, look for signs of a leak in the head gasket, such as milky color in oil, white smoke, or loss of engine coolant.
You may want to clean all the connections to and from ICM, and put dielectric grease on the connectors. you can also put the grease in the ends of the coilpack that goes over the plug. It keeps moisture out.

So, Given the things you have replaced / ruled out/ I would say...... bad wiring between coils and ICM......or a bad coil or two.........or possible a leak in the headgasket that is getting moisture around the plugs and causing misfires.

Keep us posted. Hope this helps.

RE: 1997 A4 1.8T Quattro rough idle problem
 

I found a decent troubleshooting guide here:
http://www.elitedubs.com/index.php?topic=988
Decided to check block 032 in vag-com, and it says:

Oxygen Sensor Before TWC Learning (Max.) Values
(0.0%) (0.0%)
O2 Sens Learning O2 Sens Learning
Val @ Idle Val @ Part Ld

The 0.0% numbers in the parenthases are in the display boxes in vag-com. I left it idling for at least 5 minutes and these numbers stayed at 0%. According to that guide in my link above, "To check for a bad (02) sensor the first thing to do is run block 032 on the VAG com. If the sensors are bad, the reading will both be 0%, replace the Front O2 sensor." Is this true, or has anyone else tried this? And can a bad O2 sensor cause random/multiple cylinder misfires? My car has 97,000 miles on it, and I don't have any previous owner maintenance records so I dunno if the front O2 sensor has ever been replaced. Oh, and if I do replace the O2 sensor and then check block 032 again in vag-com, should it give me values other than 0.0%? Lemme know, thanks!

RE: 1997 A4 1.8T Quattro rough idle problem
 

Oh and I'm also trying to figure out how to check the wires that plug into the coil packs, I don't know how. I have a DMM though. Any walkthroughs on that?

RE: 1997 A4 1.8T Quattro rough idle problem
 

Yea, the O2's are either not plugged in, or totally shot, funny you are not getting a O2 CEL. Even at idle they change values.

RE: 1997 A4 1.8T Quattro rough idle problem
 

Well, O2's sound like a good place to start then.

Would a 0% O2 sensor reading cause misfires?

What do your plugs look like now, after driving on these new plugs for a little while?

RE: 1997 A4 1.8T Quattro rough idle problem
 

I'll start searching for a good price on the O2 sensor.Should I just replace the pre-cat one? I haven't driven that much since I put the new spark plugs in, maybe 100 miles or so, but I could take a quick look today when I get home from work.