Hi - Audi owner of two weeks and already visited this forum multiple times. While I didn't plan on it I'm relishing the challenge of becoming an amateur mechanic. Thanks to you all for being here!

I have a 2003 A4 Quattro 1.8T w/ ~71k miles. The CEL came on steady the day after we bought it, and so far it has been to both the dealer and a local mechanic for diagnosis/repair.

Current codes

P0300 - Random multiple misfires
P0301-P0304 - 3 & 4 seem to occur most frequently but all 4 have come up at one time or another
P1111 - Oxygen sensor regulation bank 1 lean
P1753 - Tiptronic switch implausible signal
P1762 - Shift lock solenoid short to positive

Former codes

P0507 - Idle control system rpm higher than expected
P2181 - Performance malfunction in cooling system

Work completed thus far

• Oil change
• Replaced air filter
• Replaced mass air flow sensor
• Replaced breather hose elbow that was damaged
• Replaced crankcase pressure control valve
• Cleaned throttle body and performed relearn procedure
• Performed engine compression test (all OK)
• Performed fuel injection test (all OK)
• Performed coil wiring test (all OK)
• Replaced ignition coils

If anything after all this it seems to be running worse!

Other notes

• At initial start the car seems to run just fine, but after a quick spin around the block the misfires and rough idle start
• There is also a jet engine like sound when the car is running and a lot of moving air in the engine compartment.

Any thoughts on what else I should check or look at/for? Thanks in advance!

 

Apparently the lean condition is causing the misfires, check the fuel pressure with the engine under load and change the fuel filter.

 

well for one I would check to see if your coilpacks have been replaced. Try swapping the packs to different cylinders and see if the code follows the pack. If so u can get new ones. As for the jet sound thats probably your sai pump. It goes away after the car warms up right. . . the noise? if so that should not affect the car in any way of performance. That pump is just their to warm up the air going into the system when the car starts. i would fix the packs first and clear codes and report back.

 

Thanks to you both for the feedback...

z28pete - That will be my weekend project
pa4ul - I had swapped around the existing coilpacks but the codes did not follow, so went ahead and put in all new ones. If anything it is running a little worse with the new, which is very frustrating.

I did end up taking it to the dealer and they want to replace the breather hose assembly. From what I've read this may be a good thing to do regardless but was not sure if this directly addresses the issues. Any thoughts?

 

i would say yes to changing hoses. Alot of times if a vaccum leak it really bad it will cause the car to studder or even die randomly.

 

Replace the spark plugs

 

I went through the same on my 2004. I replaced all the PCV hoses and it took care of the rough idle and codes,

This was what came out.


The elbow from the crankcase to the pcv valve was completely separated (on my daughters '01 A4, the elbow was completely gone)


and the breather hose to the connector on the back of the valve cover was completely split.


I wish I would have seen the 034 motorsports silicon parts before I replaced them with stock ones, but it took care of the rough idle.

 

Audi Tek - Spark plugs were replaced and it made no difference

johnwiz - Thanks so much for the info and pictures, really hoping that this solves my issue also. What benefits do the 034 motorsports silicon parts provide over stock? Where could I find those?

I'm waiting on a couple of places to give me estimates to complete this work so hopefully sometime next week it will be in and fixed!

 

Here is the link to the 034 Motorsport site, 034Motorsport | Performance Parts for Audi, Porsche, and Volkswagen

The elbow and the one pipe are plastic and you need to use a heat gun to heat them to fit them together. Also, it makes them a bit hard to get in place and eventually they will fail again. The silicon should be easier to work with and not subject to fail.

Getting the elbow piece out of the crankcase was probably the toughest part, especially making sure to get all the pieces out.

 

Hi again - Thanks again to everyone that provided comments & feedback. Happy to report that I found a great mechanic to work with and the car is now fixed!

For completeness, here is everything they did:

• Replaced the entire breather hose assembly (needed it done quickly so couldn't go with silicon unfortunately)
• Replaced the thermostat and sensor
• Replaced the turbo diverter valve (was losing power as it was stuck one way)
• Flushed the cooling system (was gunked up with something)

Codes they found:

• P1297
• P301, 303 & 304
• P3081
• P1340

If you are in the Des Moines, IA area and need Audi repair work I strongly recommend going to Drake Garage (www.drakegarage.com)