[SS e93]

Hey guys.

I have a 2009 335xi. I have been using Cobb stage 1 a while now, but since late last summer I have been having driveability problems. Gas economy has dropped a decent amount from roughly 24mpg to 20mpg or so at best. Driving style stayed the same. The car almost feels like it is choking. I originally brought it to BMW to check for boost leaks, which they found none, and my logs show I am hitting boost with some spikes when I let off the gas.

When I drive on a cold start, any acceleration causes the instant mpg to read as 6.0mpg. It just doesn't have the same punch either. When I floor it going up an incline at 40 or 50mph in 4th or 5th gear the car barely accelerates. Much slower than previous. I am not getting any obvious misfires. I have 75k right now and did spark plugs and 2 bad coils at 60k or so. I did walnut blasting at around the same time when misfires returned.

The only code I am getting is the p2aaf which I never got before these problems. But I understand the code means nothing apparently. Based on my logs, the HPFP actual reading is higher than requested.

TL;DR - MPG went down from 24 to 20, car is much less responsive and feels like it is choking. No misfire, no boost leaks, no definitive codes. No mods other than Cobb, and problems started all of a sudden so it isn't due to Cobb.

Here are some logs.

http://www.datazap.me/u/cfigs/stock-...data=2-7-19-20

http://www.datazap.me/u/cfigs/stock-...data=2-7-19-20

What is the best way to try and log any fuel pump related issues?

[CHECKERED]

Winter gas is worse than summer gas, I can go into details about why and how, if you want to know more google. So the drop in mpg and power is expected.

Cold start, every car with modern fuel management runs rich when first started to warm up the cats to decrease emissions. Low mpg and power is expected while the car is still cold.

P.S get a real tune

[SS e93]

Originally Posted by CHECKERED

Winter gas is worse than summer gas, I can go into details about why and how, if you want to know more google. So the drop in mpg and power is expected.

Cold start, every car with modern fuel management runs rich when first started to warm up the cats to decrease emissions. Low mpg and power is expected while the car is still cold.

P.S get a real tune

Unfortunately I know it isn't a winter gas issue. This issue started over the summer and has been pretty persistent. I keep track of every single fill up and mpg, and even during winter months in previous years it never dropped this low.

I have had my car for 5 years now and I can tell you it is definitely different from the first few years of ownership, even on stock map. It is almost as if there is no power under 2500-3000 rpm. It just doesn't feel right. My instant mpg gauge is never pinned down to 6mpg until these problems started happening, but now even going fairly light on throttle will peg it down to 6mpg on the digital gauge.

[UMich_335i]

Get an intake valve walnut blast done.

[SS e93]

Originally Posted by UMich_335i

Get an intake valve walnut blast done.

Just had it done 10k miles ago. Misfires gone and engine power was smooth, and a few thousand miles later this problem started happening.