Car: 2001 Audi A6 2.8L Quattro

Issue: Intermitent starting issue

Problem: Car starts in the begining of the day, but will not start again unless I wait 1 or 2 hours. It cranks but the engine will not start. I have confirmed voltage, checked & changed the battery, checked the alternator and the charging is fine. The air filter was changed today (and I did an oil change today - which doesn't affect this issue).

What could be wrong? If you are a Audi A6 troubleshooting expert or guru, please let me know your thoughts.

(Also, if you are in the south Bay Area (Silicon Valley), let me know if there are real Audi technicians who I can depend on with reasonable pricing.)

 

Paypal $25 to.....

Change the coolant temp sensor. Also Vag-com it for stored codes, the answer might be in there.

 

After running the computer codes, it shows no issues.. so there must be a issue with the spark or ignition modules?

The engine actually dies as I slow to a stop. There must be an issue with low RPM when I apply the brakes. When I try to restart the engine, it cranks but engine won't start.

Should I rule out the crank shaft sensor or ignition module, since the engine stalls even when I am driving and slowing down to a stop? (Do those two items only affect when I'm starting the car, not when it's already running?)

Any thoughts on solution? (If anyone is a true A6 troubleshooter guru, this one is for you.)

Thanks, RM

 

No codes at all? Not even stored ones? How did you check it?

Well, that would have been good information in your first post.

Try unplugging the MAF & seeing how it runs. Also pull a couple of spark plugs & see how they look. My thought is a bad sensor, or a vacuum leak.
I doubt it's the crank or ignition problem. If it were, the car would either not start at all, or run bad all the time.

 

Always remember the basics of a gas engine. Air, Spark, Fuel. It looks like you checked the air issue. As above mentioned by 2ks4 check the maf and spark plugs. Lastly it sounds like you are not getting steady fuel. It collects enbough to start but not maintain. Fuel filters are rare to fail as audi uses large filters. Check you filter anyway, your fuel pump and check for possible vapor lock someware in the lines. It is not like an audi to not throw a code when in your reported situation. Good Luck!

 

no start and no code?? even the crank sensor would throw a code if there was no spark ( which I bet you didn't check) but saying that it seems you have an EVAP issue and im going for the canister purge valve or the pipes to it

 

Ive seen this problem before on older 2.8L A6 cars, its hard to start if starts at all and throws absolutely no codes. We had to eventually take apart the cylinder head to find there was substantial carbon build up on the intake valves and on the throttle body. Cleaned it all off and it ran perfect again. What we do for a cheap fix (we don't tell customers) is we have someone floor the engine and have someone spray a whole can of chemtool carb cleaner down the intake until the can is empty, its cheap and easy to try just make sure to clear the codes afterwards cause its gonna throw some serious miss-fire codes.

 

Iwas recently (last week)having the same problems with my 2000 a6 2.8. <every two or three days the car would stall, then sometimes crank back up & sometimes take 20-30 min. Always cranked fine in the morning. Then during the day, would sometimes have a hard time starting, etc. etc. The problem ended up being the crank shaft sensor.

 

S***! and you didn't have a code for that? Thats strange.....

 

Man, that's an old-school fix. Useta do that with my '77 Olds Cutlass Salon, back in teh '80's... Late '80's, when I was in Ita;y, we'd just just do a WOT run up teh AutoStrada, and back again... Same effect!