[dr09]

I have a 2007 335i which I bought used last year. Since then I have had tremendous problems with the car. Initially, it was just the long crank, which would only happen occasionally, and usually after it had been cold for 12+ hours, combined with kicking out black exhaust, and a carbon build-up in the engine. It eventually progressed into RPMs when I turned on the car, and rough idling when sitting at a light, and then moved on to a more significant "shuddering" and a service engine light.

Initially, I had thought it was the HPFP, and had it replaced. Now, the service engine light has come on several times spitting out a code that sayis a different cylinder is misfiring each time. I have replaced the misfiring coils in the various cylinders that have errored, and all the spark plugs. However, since then it has spit out a new "Service Engine Soon" light. I have constantly felt like they keep fixing the symptom, without thinking about the underlying cause.

The current hypothesis on the underlying cause is that the fuel injectors are leaking into the engine, causing the it burn off the excess fuel (which leads to the high RPMs and rough idling), as well as the black exhaust.

Does this sound like the right diagnosis? Has anyone had similar issues and had different issues that I might also need to address?

Thanks!

[djjasper]

You may have wasted your time on the coils and plugs if you didn't pin down the problem. SES light is common when an injector is going bad but the same error code is reported- misfire on cylinder x.

[philiphilip]

I had the same thing exactly. It took 5 months and 4 dealer appointments between 2 different dealers to find the issue. first the did software update - no change. Then new hpfp - no change. New spark plugs - no change. Finally got all the injectors replaced last november, its been running like a dream ever since. So good chance same thing will help you out.

[GRLPWR]

+1 on injectors. I had the same shuddering/misfire problem and it ended up being due to a previous mechanic failing to install the decouplers when replacing the injectors. I also recently had a carbon cleaning. Runs great.

2007 335i approx 86k miles.

[PTinVT]

Can't help, but just wondering how many miles on OP car.

[dr09]

Approximately 62000 miles.

Replaced 2 fuel injectors that were associated with the misfiring cylinders. SES went away and long crank is gone. However there is still some shuddering when I start it up, which eventually goes away if I drive long enough. Could this mean there are still faulty injectors, or something else?

[chris the man]

Bump from the dead.

Was this ever resolved?

[kaigoss69]

I got rid of my shudder (during acceleration in high gears) by resetting engine adaptations. Fuel injectors were next on my list, but running just fine with the old ones now. 104k miles, Cobb aggressive, FBO.

[GOS7]

Good thread, thanks for reviving this.

[chris the man]

thank you all above

and thank you kaigoss69

My friend has seemed to have this problem and I can not help him figure it out. New injectors, plugs and coils. Idle is rough nothing else. His fuel pump was replaced in 2011.

numerous shop visits and no luck.