BinsuJiro

The vehicle is a 2000 A6 Avant Quattro with a2.8 L engine.

As soon as the weather turned cold. and temp dropped below 40 F, the vehicle required multiple activations of the starter. After three or four attempts the car would start catching for a revolution or two; after that it would start with surging, backfiring and extremely rough idle by holding the accelerator pedal down until it would not stall. The pedal would have to be modulated constantly to keep the idle stable; too high and the car would stall too low and it would rev high.

After 7-15 seconds I could hear something kick-in (a sensor; a computer specification; vacuum condition; fuel mixture change - I don't know what) The behavior is very regular and predictable, and after the initial startup problem EVERYTHING SEEMS TO BE PERFECT: smooth idle and acceleration; no hesitation on acceleration; good heater output; good power and mileage.

I DON'T believe it has anything to do with the coil packs, injectors, spark plugs or spark plug wires. It is possible that the problem is related to O2 sensors or secondary air control, and of course it could be an air leak.

I am hoping that with this description someone on the forum can help me narrow down the problem, since the vehicle is used every day for commuting and I only have access for short times every day.

Just Me

real answer is pull codes. I might suspect a coolant temperature sensor - it sorta fits the bill (not entirely) and is known to fail with great regularity.

G

BinsuJiro

Sorry I didn't send this yesterday; it was on a different computer, and when I reviewed this, I noticed the Temp Sensor. The first three faults have recurred randomly over a period of time, but don't seem to affect much. I already had a temp sensor on order before this problem, so either today or tomorrow I should have that part.

Address 01: Engine Labels: 078-907-551-ATQ.lbl
Part No: 3B0 907 551 BA
Component: 2.8L V6/5V G 0050
Coding: 07252
Shop #: WSC 06133
VCID: 63CE643CF14EA13

4 Faults Found:
17539 - Oxygen (Lambda) Sensor; B2 S1
P1131 - 35-10 - Internal Resistance too High - Intermittent
17831 - Secondary Air Injection System; Bank 1
P1423 - 35-10 - Insufficient Flow - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1
P1113 - 35-10 - Internal Resistance too High - Intermittent
16501 - Engine Coolant Temp. Sensor (G62)
P0117 - 35-10 - Signal too Low - Intermittent
Readiness: 0000 0000

BinsuJiro

Glen, I pulled the codes and posted them last week, and yes there was an indication of a problem with the coolant temp sensor, but there were other codes also.

Since you decided to reply to my first posting with the comment about the codes, I would expect the courtesy of a reply regarding the codes that I posted.

Thanks

rossej

[QUOTE=BinsuJiro;24219318] I already had a temp sensor on order before this problem, so either today or tomorrow I should have that part.

Did you replace the coolant temp sensor?