Xcytor

Hi everyone,

Got a 2005 A4 2.0 that starts and runs fine (little sluggish for a turbo)...but then after about 2 - 20 minutes of driving especially on the highway, it starts bucking, hesitating (loosing power). If i try to gas it while this is happening, I hear the engine rev and see the RPMs go up...but there is no power during the hesitation.

Then the car gets really sluggish like its flooded bucking more frequent...but random, and will stall if I dont keep giving gas and have to come to a stop sign. When i try to put in neutral and rev it, it sounds muffled and slightly sounds like misfire or backfire. There is no smoke from the tail pip but you can smell exhaust just when I do that.

After that, I can start a few times and it gets over it and runs for a while but a little boggy....till it bucks again.

The codes I get back and forth are P0171 Lean Fuel and P0192 Low pressure fuel rail

I have Replaced

MAF
FUEL FILTER
FUEL PUMP HPFP with SENSOR
PCV or VALVE Breather
VACUUM PUMP (it was leaking, but didnt fix the issue)
PLUG
NEW COILS

Today Im repairing the Coil wire harness clips they are cracked and broke and then replacing the Diverter valve with a new D version

Any other options?
O2 Sensor (Precat? Post cat?)?
The valve cover is pretty clean.


Any helps any one could provide would be greatly appreciated. Ive been going at this for 4 weeks and running gout of options and seriously going crazy.

Thank you

Xcytor

Well changed out the DV and rewired the coil harness.

Still have the P1092

BUT...the really weird part is that the engine runs smooth now but the power to the wheels seems to be slipping. It hesitates or slips but if I give it gas is can hear the engine running smooth and the RPMs go up effortlessly. If I put in neutral or park, the engine revs really fast up in to 3000-5000...but put it in gear and you can feel the sluggishness. Then it slips again.

No other codes besides the P0192

Dwes

Might not be a bad idea to change out the O2 sensor. The pre-cat one sends a signal to the injectors to lean/enrich the fuel mixture because of what it see's in the exhaust. The post cat O2 sensor also indirectly adjust mixture but thats just to get the CAT heated up so that it works more efficiently. Most sites/manufacturers say they're good for about 100k miles.

Xcytor

Thanks for the reply Dwes

Yeah, its ordered. Figure Ill do the upstream first. Cant hurt.

Also, just realized I cant rev my RPMs past 4k. That sounds and feels like the redline of the car. Not sure whats up with that.