JorgenA4

Over the past few days(3-4) I have noticed under light throttle my A4 is bucking/pulsing as you climb through the RPMs in first and second gears. Once you get into 3rd I don't notice it. If I push the gas further it tends to go away as well. Seems a little odd, anyone have any ideas for somethign like that? I am clearing the codes and will run the car a bit to see what new codes pop up. I know I have bad o2 sensors but that has been forever since I bought the car.

Lago Blue

Here's my theory:

In cold weather coupled with short trip driving your engine may be producing more oil/water sludge/mucous/phlegm etc. As you may also do more "idling" during winter, this may more easily be transported by the CCV System to the IAC. I think this stuff may momemtarily "choke" the IAC. This may also tend to gum-up and/or want to freeze the IAC.

I have experienced only very briefly, something similar to what you descibe. IIRC, I did read that the IAC is in use until you are into the throttle more than I'd originally thought. Could this be what you are experiencing?

I wasn't able to really restore my VDO IAC's performance until I did the detailed cleaning possible after removing it's lower cap. It may also be a good reason to get in there and polish that passage-way leading from the IAC into the Intake Manifold, similar to what is done as part of the EGR Passage Procedure.

http://forums.quattroworld.com/12vv6/msgs/414.phtml

JorgenA4

That could be it. I haven't checked codes again yet. IT seems to be happening less often now. I plan to try and change the oil this weekend if it warms up a little. I did a quick seaform this weekend (half-3/4 in the vac line the remainder in the tank) and that seemed to help out a little. I did start to notice some idle drop when sitting a lights, not bad enough to stall but it started slowly last time and eventually would die at a good number of lights. I gues when it warms up I need to just get in there and clean out that whole system again, got rid of the idle problems last time and that was a little while ago.

450god

This is like my problem, except when I start mine I have to give it some throttle to even get it fired up, then it idles a little high, then at slight throttle it chokes out, but it seems to be getting better but still does it? In my other post someone said maybe a breatehr hose ontop of my manifold, but ya if you figure yours out let me know!!

JorgenA4

The problem seemed to go away a little bit but t is back now even worse. Scanned codes and found the following three 02 sensor codes (knew about these already just never replaced them) P1206 and P0306 Which woudl be malfunctioning fuel inejctor system on 6th cylinder and missfire in 6th cylinder. Any ideas where to start finding a replacement injector? Assuming I shoudl start there.

JorgenA4

Well I ordered up a "new" (used) injector. Anyonce know which cylinder is the #6 on these engines?

Lago Blue

explanation here (follow the links back):

https://www.audiworld.com/forums/sho...light=cylinder

photo here:

https://www.audiworld.com/forums/sho...ylinder+number

JorgenA4

Well I decided to not mess around with it and sent my 6 injectors for cleaning and testing on Monday. They alltested ok and cleaned up fine. now I am a little more concerned there is another larger issue. I will be receiving these tomorrow or Friday and will install on Saturday or Sunday. Hopefully I can install and the problem is solved, if not then the search for an elecrtical gremlin starts.

JorgenA4

Well I installed the newly cleaned injecotrs and still have an issue on cylinder 6 P1206 still pops up and the car still smokes a bunch and runs like crap. I tried swapping the plug wires with a cylin 3 and 6 and then plug with 4 and 6 and the issue still shows on cylinder 6. Any other iddeas?

Lago Blue

be pointing out that you might want to check the input signal to that injector. This can be done with a good automotive multi-meter. Compare the time the injector is open on #6 vs. any of the others. What does the smoke look like? Perhaps that injector is being held open electrically. I made a harness adapter that allowed me to easily meter an injector while the engine is running.

DTC P1206
Cyl.6-Fuel Inj.Circ. Electrical Malfunction