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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > 335i oscillation while cruising only



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      Today, 12:07 PM   #1
jyeah
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335i oscillation while cruising only

Hi All,

I have been experiencing an extremely weird oscillation while cruising and keeping my throttle steady for a while now. The feeling is as if the car is oscillating with a very slight stalling feeling followed by a slight pulling feeling. The moment I let my throttle off or press on it further, the oscillation goes away. The rpm needle also fluctuates. I tried doing some logs and it seems like my HPFP is very unstable, fluctuating up and down, while the requested stays constant. My LPFP is very stable as well.

Has anyone experienced anything like this? I have Cobb V3 installed with the newest firmware and it is pro-tuned. I also have tried clearing the codes, resetting the adaptations, and flashing back to stock. None of these helped.

A while ago, I recall that the oscillation went away for a short while when I added a bottle of techron after a fuel up, but came back after that. I don't know if this was a placebo effect and I haven't tried it again.

Here's a link to my logs.

http://1drv.ms/1qxfvJT

Any help would be much appreciated!
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      Today, 12:20 PM   #2
jyeah
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Also, I tried using datazap to take a quick look. The thing I do notice is that there's usually a change in cylinder timing from 30->15 followed by a dip in HPFP pressure.
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      Today, 01:21 PM   #3
badass335
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I was just going to post the same issue. I have Cobb V3 and am going through the ptf tune as well. I've had way too many revisions and still have this issue. It seems like the car is taking off, and then a parachute opens slowing me down and then the parachute rips and i take off again.

I had OFT with Procede stacked and the car ripped through the gears. I am running a FBO car with Meth. I had Procede control my aquamist meth and was running IA8OS ecu.

I then had an ecu failure (mosfet issue) so bmw replaced it with IJE0S now. Also got 6 new coils and injectors and plugs. As such, i removed Procede/OFT and got Cobb v3. Connected Aquamist directly to ECU.

I am trying to troubleshoot as not to blame tunes. I replaced the Boost Solenoids with all boost hoses and then i read somewhere that vanos solenoids could also cause this so replaced that as well. Running out of ideas.

I should also mention as OP stated, i can be driving with throttle constant and the car is surging or fluctuating though the pedal is held constant.
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