CE light, rough idle, intermittent stalling...

[phong468]

2000 2.0 NB 70k+ miles:

Looking for some advice on where to start looking before we take the car into the shop. This is my GF's car and I am by no means a VW expert (why can't she drive a Subaru) but I am learning as problems seem to be rapidly adding up.

Problem:
Check engine light. Rough idle, after bringing the RPMs up and letting them fall. Appearently, the car died several times as she came to a stop when trying to get it home. Got back into town and started the car yesterday noticed the rough idle and pretty rich smell to the exhaust that didn't seem to go away after the car warmed up. This is normal for Subies in cold weather but no idea for VW's?

Possible problems gleaned from a search:
1.No I haven't scanned the car yet. I am going to see if anyone from Dubsnorth might be local and have a VAG-COM.
2. Bad Oxygen sensor
3. Bad MAF
4. Bad Vacuum line/connection. (maybe caused by my recent battle with headlight replacement(s)).

Any other ideas or are the problems symptomatic of a particular problem? We are poor law students, so avoiding the dealership/shop would be great.

Thanks in advance!

[speedie]

I would suspect the MAF. Try unplugging it and see if the idle and normal acceleration returns.

When were the plugs last changed? VW recommends a plug change every 40k miles. Along the same lines, were the wires replaced? If not, was a plug wire tool used to pull the wires? VW wires are very fragile.

Also when was the fuel filter changed (silver cylinder under car on passenger side)? Every 40k miles is a good rule.

Bad vac lines usually give you a light, but everything is normal unless the line is totally unplugged. There is a vac line diagram on the shroud above the radiator. Check all lines using it as a guide. If the car has the cloth/rubber lines, yeah definitely pull those off and replace them with better hoses (inside diameter = 3.5 mm).

The last option is bad o2 sensor. VWs have two, one pre and one post cat...they are easy to find when under the car.

It is not normal for VWs to have rich smell in the exhaust.

[phong468]

Well I am pretty sure that none of the scheduled maintenance has been done unless by the previous owner. So it probably needs plugs, wires, fuel filter, etc... Ughhh, more work.

I will start with your suggestions and report back.

Thanks for the help!

[Porkchop]

You're on the right track and sounds like you recognize its all guess work without the code.

But, just for the heck of it, check the vacuum line between the fuel pressure regulator and the intake. Take the plastic engine cover off and it's on the left side of the aluminum intake - right on top. The original braided line shrinks and eventually comes loose. Replace it with some standard vacuum line from the auto parts store.

[ATCtech]

I have a similar problem here. About 50k miles on the car and my girlfriend has had the same O2 sensor changed 3 times in 2 years. I've also done plugs/wires (replaced using VW wires with the proper tool) summer 2004 and the vacuum hose replacement using proper silicone hose. Even after all of that, every 3-4 months it's back to the CEL on, an O2 code & a misfire code (mutli-cylinder) with a wicked way-too-rich smell. This time at my insistence it's off to a VW dealer for (hopefully) a more thorough diagnosis than just a new O2 sensor and a CEL reset that her independent repair place seems able to do...

We'll see. I don't like this engine.

Bob

[phong468]

Ok, went out to look at the car again today. First, it wouldn't start so after a no go with a jumper battery I had go buy a second set of cables to rig up a longer connection. I eventually got it started and I am guessing a new battery is order amongst other things.

Checked all the vacuum lines all looked good and connected. Next, I unplugged the MAF and bingo the idle smoothed right out. Plug it back in and the idle gets rough again. So hopefully this is the problem. So do I replace the MAF or is it possible to clean it? I have read in a few posts about cleaning the MAF but that doesn't seem to have fixed the problem long term. What does a new MAF cost? If I replace the MAF how do I clear the CE light? Can I just reset the ECU by disconnecting the battery or does it require something more invasive (dealership/shop visit), being a VW I bet it requires more?

Thanks in advance!

[yellowherbie]

I have replaced all of these things.

I think we should start our own "sensor" club! Its a pain, I tell ya'

-but its still cheaper to fix, then having a car payment-

[Scarab 1]

Coil Pack?????????????????

[phong468]

Couple of quick questions before I replace the MAF sensor. I am going to have it scanned at autozone to pull the codes and then order the part if it looks like that is the problem.
1. Is it ok to drive with the MAF sensor unpluged?
2. If so for how long?
3. Are there any downsides to buying a remanufactured MAF sensor?

Thanks!

[yellowherbie]

When I bought my maf, it was about 70 dollars, because I coulnt find one at a parts store.

When I saw the old one, it looked brand new. So, I was just a tad confusied. But, hey, it worked. I also had the fuel filter replaced at the same time.

Good Luck!

[phong468]

Popped the new MAF in today and the problem went away, so it appears the MAF was to blame. Now on to all the other problems like replacing the alternator that must be made of gold based on the price of new/rebuilt replacements...