2004 330i, 152K miles: Most of the time, but not always, when I start the car it would stumble for a couple of seconds with virtually no throttle response until it evens itself out or throttle gains its sensitivity and actually revs up the engine a bit. Car has no codes, fuel filter looks recent. The car does this regardless of the engine temp, it could be fully warmed up or stone cold. Holding the key in the second position for a few seconds (fuel priming) does not help the issue. Fuel pressure at the rail looks right during priming and while running. Car runs good otherwise with good power and no codes, stable RPM while idling cold or warm, no vanos noises or any other abnormal noises for that matter. Battery checked out ok, spark plugs look normal. Any further ideas on the root cause? I got the fuel pump here, but I have a strong feeling it isn't fuel related - don't want to just start throwing parts at the problem. Am I missing something obvious?
Thanks.
Hi mate it could probably be the breather pipes they start to perish because they are poxy plastic i would start checking them easiest way is to replace all of the and the breath pipe filter you can usually get it as a full kit i think there is 5 pipes an a filter but they dont come cheap an take some advice dont buy cheap ones because you will end up spending out on dear ones any way so go dear first hope this helps
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turn the key to position 2 (dash lights buy no start) for 30 seconds, then turn it off for 10 seconds. Then start the car. Could be an adaption fault and the key thing helps reset that. Otherwise you'll need a spare laptop, cable, and software to do more. (See the diagnostic section of the forum.)
Johnny Murray
Not trying to be a prick.....But how many BMW mechanics, shaddy tree, or waht...actually respond to the people asking valid questions on here....bimmerfest?
When you say no codes, are there any shadow codes?
I bet you'll find misfire codes. It's very common with the M54B30
No shadow codes were present. I swapped a fuel filter thinking it may be the culprit, but the original one ended up being only 2 years old, Kayser was the brand - no change after fuel filter swap obviously. I have checked injectors and none of the leaked. Decided to bite the bullet and swap the fuel pump and whatdoyaknow - car now starts without any stumbles or hesitation.
Thanks for your help!
Spoke too soon I guess. It definitely starts better, but the stumble is still there. My wife reported lack of throttle response followed by a jerk forward on the first application of throttle after start up. Thinking it could be a sticking flap in the throttle body?
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