This last week I did the timing belt/70,000 mile maintainance on my my A4, with the 1.8t motor. Before I would sometimes get a little shuddering and the check engine light would flash at stop lights from time to time. I figured that was from coilpacks or plugs, so I replaced all those while doing the timing belt stuff. I got the car put back together, and it started right up, first turn of the key, just like it hadn't been worked on. It did the old "warm up" idle thing at about 1,100 RPM with no sign of a problem. Once it dropped back to about 900, the check engine light began to flash. Drove the car to the gas station, about 2 miles, no chk eng light. Drove back from the gas station, the check engine light was on constant. Had a buddy with a vag com setup read the codes, and got a random misfires on al cylinders message. My thought right now is that the coils or plugs were causing the misfires before, and now the message is because the engine is improperly timed. Could it be something more straightforward? I hate to have to get a new tensioner/dampener and tear the car all apart again. Really no guarantees I'll get it right this time, as it looked pretty good to me last time. And started up just like it was perfect. The only time that light flashes, to indicate the misfiring is happening right then, is when the car just sits, at low idle, like in the driveway or at a traffic signal. Any suggestions are appreciated.

 

Hrrmm, now wondering if it isn't actually a bad Ignition Control Module.

 

Could be a bad ICM if you say you did your timing properly. I hope by timing you mean replacing pump, tensioner, thermo, and etc., not just the belt itself.

Bad plugs? Doubt it. You can try cleaning yours. A bad coil pack and wires tend to do wonders for your idle so you can look into that also.

 

Yeah, I did the full "Ultimate Timing belt kit" dealie-mo-bob. And it doesn't do it all the time, only at idle, and really only after it has been sitting at an idle for a minute or longer. Put in all new coil packs and NGK platinum plugs while I was doing it. I think if it were the timing, it would be running rough all the time, and not accelerating smoothly.

 

You aren't sucking in much air at idle, and sometimes a bad/dirty MAF will get confused.

 

That is another possibility that occured to me. Hmm, which to check first.......

 

Just to be sure on the timing, after tensioning the belt, did you line up all marks and hand-rotate the engine two revolutions and recheck that all the marks line up? That's your most sure method to ascertain proper timing and it seems to be what everyone neglects to do.

 

JUst had the same problem heres what you do

-pop off valve covers or cover
-get car in service position again
-turn the crank pully to tdc and see if the timing marks on the cams match with
the mark on the crank

so make this
http://i147.photobucket.com/albums/r...y/DSC_0031.jpg

match up with this

http://i147.photobucket.com/albums/r...y/DSC_0036.jpg

(as you can see in the above pic my crank was wayyyy off i had the same problems now
fixed).

to line it up your going to have to pop off the timing belt again put the cam bar in place and attatch the crank pull wheel make sure you put a pin in the dampener(with no belt attatched) then turn the wheel until it lines up ive found its ok to be a little to the left of the timing mark but any to the right and your fucked!

after this put everything back together roatate it and make sure it all matches up.