arjun90

How Does My Idling Engine Sound? There are currently two cylinders misfiring; will need to troubleshoot soon. Also, Fan Control Module and / or Passenger Radiator Fan might need to be replaced.

Would like to know how you all perceive the sound of idling engine. Please let me know, thank you.

jcman

Truthfully listening to a recording of your engine is a mute point because the acoustical accuracy may not be correct and might enhance or cancel out the true sound of what you hear and I or others don't. I own a 2004 A6Q 3.0 and as others have said or noticed that the engine does have a slight tractor diesel sort of sound until the hood is closed.

If you have a flashing CEL light and you already know two cylinders are misfiring do not run the car at all unless you're ready to replace a catalytic converter or both, check the plugs or switch the effected coil-packs to a different plug to verify the replacement of the part, seems to be common on the 3.0 at one point and Audi did have a recall campaign on replacing them all back in 09 or 10.

arjun90

Thank's a lot. I stumbled upon many YouTube videos of the Audi A6 C5 3.0L (2004) exhibiting the same sound. I remember replacing the flex pipe in the summer of last year, and the engine sounded extremely quiet. Perhaps, this time around, the spark plugs and / or coils need to be replaced as you mentioned. The Catalytic Converter seems to be functioning normal, no exhaust problems that I can see. However, the Air Filter definitely needs to be changed.

Some time ago, the previous owner had the main computer replaced with a Brand New one from Audi because of water contact. I strongly doubt the mechanic performed a proper fuel trim.

I have the XTool VAG401, perhaps I can verify what the values are.

jcman

Sounds like you've got it covered but just you know a flashing CEL means damage will occur and the ECU automatically adjusts fuel trim according to the engine coding and input sensors, I'd doubt that a Audi service center missed that coding on the ECU.

arjun90

The CEL is not Flashing in intervals, its Solid; nothing really serious, since as per the Fault Code List, either the Spark Plugs or Coils need to be changed. Also, there is pending work on the passenger-side radiator fan; either the fan is dead or the Fan Control Module needs to be replaced.

The previous owner didn't deal with an Audi Service Center; instead dealt with a apparently reputable local mechanic, sourced the original Audi Parts.

It suspects me that the Fuel Trims were not programmed correctly.

A few months Audi had confirmed with me that the recalls were addressed in this vehicle. Though, I'm not if this vehicle qualified for the Ignition Coil. Is there a documentation pertaining to this?

Thanks again.

jcman

I don't know what XTool VAG401 is or how much it shows vs Vagcom/VCDS, I do know that my 04 3.0 uses a 8E0 909 559 R controller (ECU) with a coding of 0016752 according to Vagcom.

Do keep in mind that fuel trims are not programmable and there is no re-coding for that parameter unless you are chipping the ECU for it's own mapping, the factory Bosch Motronic ME 7.1 ECU determines fuel trim by engine temp, load & RPM, MAF, pre O2 sensors, BARO, cam angles and etc..etc.

This engine was a unique build for Audi for it's time and some would say more of a curse than a blessing based on the variable intake cam timing and two step exhaust vs the other C5 engines along with the usual issues the other ones have too, I can be very sure that Audi would not open a user input option on vagcom that could lean-out and toast valves or pistons let alone excessive fuel enrichment to cook a cat under a warranty period at that time or present.





 




arjun90

The first thing on my To-Do list is to troubleshoot the spark plugs and coils to address the 2 misfires (Cylinder's 5 & 1; not sure if this shows any resemblance). My 3.0 uses the same ECU as yours. The VAG401 tool was built as a portable VCDS tool (to cover most functions, but not all by all means); a lot of positive feedback, as per other threads. Still getting used to the interface.