Short Throw

In the past year or so, my car has been running really poorly. I have taken it in to the dealer and some local import specialists however they all say the same thing, "no code, so we can't really troubleshoot what we don't have a diagnosis on". Gone are the days of mechanics that can troubleshoot a motor free from computer software etc.

Long and short is this:

'04 S4, 4.2 liter etc. etc.
Mods to engine include: cold air intake and AWE cat backs and DP's

So, I suspected that the car was running rich for some time now and kept wondering why and noticed that the exhaust note changed over the prior several months. Just sounded "rougher", certainly the engine seems to struggle more and runs pretty rough all around. Again, the mechanics say no missing etc. as nothing showing up on computer.

After replacing plugs, coil packs, 02 sensors I went to what I felt was the last place, the catalytic converters. I actually ordered bran new AWE dp's with cats in them from AWE direct. Initially, the exhaust note changed and teh car seemed to run better. GEt this, upon visual inspection of the cats, the packing in the cats is fried adn the cats were burned up. So, I'm guessing my suspecion is currect of a car running rich as the excess fuel appears to be burning up in the cats hence the fried packing.

Now, I'm back to a car running roughly and I suspect another set of cats are on their way out.

I love this car but want to get her running smoothly again. Any help is GREATLY appreciated!

Sportvierwagon

Don't know the milage but I'd check the MAF, especially since you have an cold air intake. Heard that some oil can get to the MAF and cause problems when using a cone filter. Take it apart and clean and put the stock filter on and see what happens.

s4master1

obviously the car has been running too rich and also the cat failure is common on 4.2 engines
However tell your mechanics to get a reading on channel 32 for idle and part throttle and you will see where the mixture is
the ecm has the ability to record the long term running condition of the engine
definitely remove the intake thing, they usually damage the air flow meter
if you have more than 50k miles replace the maf
don't forget the cats are cover by emissions warranty
hope this helps

darrenb

One more thing... I have a 4.2 that was running bad with no fault codes also. Turned out that the shafts for the variable intake manifold were stuck. Mechanics unjammed it all and its been awesome since.

Short Throw

I wil check that out, thanks for the insight on this. I've also checked out/replaced the MAS and no change. So, on to the next step, I hit the dealer this Wednesday and asked that they put the best tech they have on the car, we shall see.

markN1689

Any update on this? My b7 is running rich in bank 2. I looked at the spark plugs and they were black and fuzzy on bank 2 and just slightly wet on bank 1. I replaced and the bank 2 rich light is back. Most write-ups on the intake flapper deal with the stuck bearing part but what if the actual flaps are sluggish or the pivot on the flap itself gets stuck. For example my flapper appears to work when looking at the engine bay and reving the engine but its the flap inside the intake man. that I cant see...(I think I can hear at least one flap moving when I move by hand)

What did the tech say about your car?
TIA

duncanto

definitely do not oil the intake (i.e. very very little oil). oil will will seep through and gum up the heater, wires, etc. which will in turn cause an improper signal to be sent to the ECU.