iknowthetruth

Hello AudiWorld,

I have been chasing a hot start issue with my 2009 Audi A3 2.0t Quattro for a long time now and would appreciate any assistance. This car has the CCTA TFSI engine.

Basically if the engine is brought up to operating temperature, turned off for ~25-35 minutes, then started again it will turn over, run rough for about 10 seconds and then die. Successive starts will turn over and quickly shut off again. If I wait another 20 minutes or so the car will start and run no problem. Usually this is after the temp needle falls below operating temp.

I have never had issues with the car dying under WOT or while moving. No codes were stored when running a full VCDS AutoScan. Never seen a code for that matter.

My best guess right now is something fuel related. I have attached a log of the hot start failure and a log of a hot start that did not fail from VCDS. The one that did not fail was after shutting the car off and then quickly starting it back up. This seems to work most of the time. The problem only occurs if the car is hot and left sitting for a period of time around 25 minutes or so.

The failure log indicates that the fuel rail pressure is not meeting the requested amount and the duty cycle of the pump(I believe this is the LPFP in the tank) is slightly higher than normal. Then the fuel pressure drops to nothing and the engine stumbles to a stop.

The Fuel Pressure Regulating valve(N276) seems like a culprit, along with the Fuel Pump Control Module in the tank connected to the LPFP. Ive read posts about both of those producing weird fueling issues when hot. Id like to be more confident in my troubleshooting before I throw $110 down on a new control module, or more for a new HPFP/N276 valve.

Parts that have been replaced so far:
Fuel Filter
Spark Plugs
PCV ~ 10k miles ago
Rear Main Seal ~ 10k miles ago

I would like to know: In block 106 in VCDS, is the "pump duty cycle" referring to the duty cycle of the in tank LPFP or the HPFP at the fuel rail? This will change how to interpret the logs. If the duty cycle is the LPFP it appears more like the N276 is failing, but if the duty cycle is of the HPFP I am leaning toward the control module being the problem.

Anyone have any similar experiences or anything to add to this?

Thanks!

PITAS3

Hey I know this is old but did you ever figure out your problem? I’ve got a 2015 s3 that’s having similar issues based on your log.