Hey guys. My g/f has a 2001 Audi A4 1.8t quattro. It's a great car but started having some check engine light and small hesitation problems a few thousands miles ago. We worked through those problems (o2 sensor, coil packs, MAF sensor and SNOW CATCH WTF IS THAT) and had the check engine light off, but she got back from Rome recently and the problem started up again. (car was used while she was gone)

At first only code p0171 running lean bank 1 came back, but then we were coming out of Best Buy and it would barely start and run. I had to give it gas to stay running. Checked codes and got missfires on 3 cylinders and running lean. Cleared em, drove home with hazard lights on as it sputtered into the driveway. Checked codes again and had misfires on all cylinders, but no running lean code. Car wouldn't stay running for more than a few seconds. Swapped a coil pack and still ran light ****. Changed plugs, old ones were kinda bad, still no dice.

The ignition system (plugs + coil packs) seems to be in working order. Not too sure about the fuel system so I was hoping someone would be able to point me towards the fuel filter or the fuel pump relay I hear people talking about?

Also, the MAF sensor was not replaced, only cleaned and then the check engine light went away a while ago when her car was serviced. The light has never come back on, but has anyone had any problems with their MAF sensors and no check engine light?

Just looking for some direction before I take it to the dealership to get robbed by outrageous prices. Anyone have a service schedule for this car as well?

 

Could be the Ignition Control Module. Thats a common cause of misfires, its the little square box located on top of the airbox.

 

wut dallas said. you should be able to do it yourself, just make sure you have the battery unhooked. now when you unhook the battery, it's gonna put your radio on lock so make sure you have the radio code or go to autozone and they sell a cigarette lighter thing that holders a 9v battery and you can stick it into the cig lighter to save the radio from being locked. it costs a hour labor to get the code from the dealership, freaking thieves.

 

Hey thanks so much for the replies! I'll be sure to check it tonight. I'm at work so I can't do a search ATM but will I be testing this unit or should I just try swapping one out? Thanks again guys; hoping this will solve the problem!

 

http://forums.audiworld.com/a4/msgs/1594531.phtml thats how you can try to test it, although many of the posts on another thread said that it wasnt possible to test without an LED test setup, so basically its something you just replace as far as I know. If youve got time that test might be worth a try, that guy does sound like he knows what hes doing.

 

I agree it's most likely the ICM.... It is an expensive lil part and you can't return it unless you know a mechanic that is tight with their supplier.

 

Ok guys... I've made a little progress with the car so I'm gonna write a little bit and maybe you guys will see something that can help me with my problem!

The car is a 2001 and my research tells me the car does not have an ICM. Can someone link me to some info if I'm incorrect?

I hooked my car (1997 3000GT VR-4, awd turbo ftw ) up to the A4 with some jumper cables. I proceeded to crank the car over for a few minutes until the check engine light came on. The car wouldn't run, but i got p0304 code. Swapped the coil pack to cylinder 2, and the code followed. Changed it with an old one and the car started to run. Really rough idle, but above 1200 or 1300 RPMS the car smoothed out to almost perfect.

So I got some ***** and decided to try taking it down the road, even though the last trip in the car was 25mph on the shoulder with hazards. Definitely had minimal power, but ran pretty smoothly. Half way down the road check engine started blinking and got Random/Multiple misfires and misfires on all cylinders (P0300 - P0304). Cleared em and kept driving, check engine light started flashing once more for 20 or 30 seconds but went back off. When I got home had pending codes for the same misfires plus p0170.

p0170 is fuel trim malfunction. I used to get p0171 a while ago but after cleaning the MAF it went away. Now that the car is running I have made a list of things to be replaced as follows:

1- MAF sensor (Old problems so might as well just replace it for the lean condition)

2- Fuel filter and/or fuel pump (Clog would make it run lean as well)

3- rear O2 sensor (front was replaced but I'm not sure how important the rear sensor is to fuel trim)



Sooooooooo now I ask you follow Audi fellas...

What other sensors or conditions could cause the car to run rough at idle and not show a check engine light (p0170 only came on once)? How much does the rear O2 sensor have to do with fuel trim? What do you think about the fuel system? And any other help would be appreciated!

Thanks again guys and thanks in advance.

-Schank

 

Im not sure on the ICM with a 2001 they might not, I coulda swore i saw an ICM on my buddies 01... Id try unhooking the MAF and see how it does. Rear O2 sensor is for emissions only, not fuel trim. Could be a fuel delivery issue too i guess, if it was more likely fuel pump then filter since it happened so suddenly.

 

Hey guys just wanted to update. Car is back and running good. New MAF solved the problems. The car drove with all the symptoms of it but I didn't actually check by unplugging it. I knew it was a problem before so I went ahead and replaced it anyway. Like always, 2 days of running fine and the check engine light came back on. (dammit Audiiiii!!!) But it was only p0301 so I swapped in a new coil pack and she even gained a little pickup.

Hopefully someone can find this info useful in the future! It doesn't always end grimly. (haha i hope) Thanks for the input.

-Schank

 

good to hear you fixed it, but.....

a few minuets of cranking is a good way to blow your stater. never crank it for more then like 10-20 seconds consecutively.