Marketthis

Cold start mystery

2003 Audi A4 1.8t Quattro (68k mi) - all stock - just purchased used

Starting Issue:

-Occurs when the cars engine is cold, and it has sat for 4+ hours
-Engine turns over fine, goes up to 1,200 RPMs and then starts to sputter/misfire with a flashing CEL - lasts for about fifteen seconds (CEL remains on after the starting issue occurs 2 or 3 times)
-Idle returns to 800 RPM after a minute or so and appears to run fine - CEL goes off - slight vibration can be felt, not sure if that's normal for Audi's or not
-When in motion, the car runs great, however, when at a steady speed and RPMs held somewhere between 1,600 and 2,000, the RPMs surge +/- 100 RPMs which can be heard from the engine as well
-Car shuts down without problems, and if restarted within an hour or so, it starts without sputtering or CEL flashing


Other notes:

-The engine made a ticking noise on two separate cold start occasions, however this was not a typical occurrence
-There is a rich smell of exhaust that is noticeable inside the car on start-up and when the car comes to a stop, or operates at low speeds.
-The gas mileage doesn't seem to be correct, averaging 15 - 20 MPG with a mix of city and freeway driving
-The dealer in which the car was purchased, analyzed the starting issue and put in a new Coolant Temp Sensor. After I picked the car up from this repair, the first few cold starts occurred without any misfire or sputtering, but on the third cold start the issue reoccurred.

Car was found to have a P0300 random misfire code.
Car has new ignition coils, plugs, and coolant temp sensor.
Audi inspected and replaced fuel injectors with no change in symptoms

Now the car has been at Audi for three days, no word yet on what's going on.

Ok mystery solvers - throw out some ideas.

Tgr_Clw

tracking.

Ertman

VVT or cam posistion sensor (hall sensor)

Bob@Stratmosphere

Any signs of leakage?

Marketthis

Just heard from Audi. They said they think it was a bad cylinder head gasket. They fixed it (under warranty) and a tech is going to take the car home and drive it around a bit to see if that solves the starting and surging issue.

Weird thing is, I didn't notice any smoke coming out the tail pipe.

I'll keep you all informed.

Subliminal

They might be sticking in the valve seats. But, I don't know. Thats a tough one.

Oil pump might be having some issues.

Aarononymous

I would start with the re-flash of the ECM to correct the cold start misfire. If that doesn't work an injector/induction system cleaning (not the bottle you put in the tank).