Banger1

Folks

Can anyone advise me why my engine is running very lumpy - it is most noticable whne the car is accelterating up hill in 3rd gear.

It is like the car has a very slight mis fire, and on Saturday when driving the car realy hard the engine did misfire at just over 3K rpm.

I don't know where to start with this one I hope that some of you could throw some ideas in.

Just on question I have - I have put in the standard plugs and not the platinum ones could this be having any effect on the performance, the plugs were changed about 3k miles ago???

Thanks in advance

Banger

MattKA4

Can you get ahold of a VAG-COM? That should tell you if you're misfiring

markbradford

Log misfires - if you're getting some, note which cylinder and regap that plug to a slightly smaller gap.

Andy_FL

Possible culprits:

spark plugs
coilpacks
ignition amplifier (on '97-'99.5)

Really need a VAG-COM to narrow down the problem. Good luck

Andy

Banger1

Re: What year? the car is a '97 with 88K miles

Andy_FL

...here's what I recommend. First replace the plugs. Yes, I know you just did them not long ago, but it's the cheapest part and sometimes overlooked. They should come properly gapped, if not, I believe they need to be in the .030" range.

If that doesn't do it, it's either your ignition amplifier (see pic) or your coilpacks.

<img src="http://pictureposter.audiworld.com/12690/ignitionamp.1.jpg">

On a '97, I'd put my money on the ignition amplifier (a $180-300 part, depending on where you buy it). Maybe that's just because it failed on mine, but it seems to be the culprit most of the time for misfires on nDBW cars. Here's how you test it: <a href="https://forums.audiworld.com/a4/msgs/1594531.phtml">Ignition amplifier / Power output stage diagnostic</a>

Try to find a VAG-COM so you can determine which cylinder the misfire is in and then you'll be able to tell if it's a bad coilpack or not.

Anyways, this is just the quick and dirty. There's SOOOO much info in the archives on this subject, and it comes up quite often, so try a search if you're interested in finding out more. Or, I'm sure someone else will chime in here and add to my suggestions. Good luck

Andy

Banger1

Andy


Thanks very much for all this info, I have a question can you tell me what the swtich/plug to the left of the ignition amp (in the picture) is for, I disconected that plug (after advise from a slight under qualified person) and the car seems to run slightly better what is the function of the disconected plug or am I just imagining the car is slightly better???

thanks

Banger

Andy_FL

Hmmm....not sure offhand. I want to say it's some type of secondary air solenoid, but I don't know. You plan on doing the work/diagnosis yourself....or taking it to a shop/dealer? Good luck

Andy

goldringer

Buy an Engine Compression Tester @ Autozone for like $25 and test out each Cylinder. That should at least give you a clue which cylinder is misfiring or not functioning. It may be your fuel injectors.

Fifth Screw

Also, try some fuel system cleaner.