Quote:
Originally Posted by 6MT_Addict
Firstly did you pull codes? Even with no CEL there may be shadow codes. As soon as a misfire is detected the engine will log a code, but if the ECU can smooth it out then it likely won't trigger a CEL. Even if there are no codes there's still data logs that can be pulled, or a reader connected to actively log values during the fault if the data is insufficient.
1. Did you code the new injectors? If not, that's likely causing or contributing to the new misfires.
2. Check your intake ducting for leaks (visual and/or smoke test) and clean your MAF sensor. After replacing my spark plugs I had missing and super rough idle at startup that turned out to be because the gasket at the downstream side of the filter box was folder over allowing air to get sucked in that the MAF wasn't reading.
Check everything from the filter box to intake valves. If you've removed the intake manifold without replacing those seals that can allow air in or your charge pipe might be cracked.
3. Run a diagnostic on the fuel pressure at the rail. ISTA can do this I believe.
Also take it to another shop unless you want to DIY. A mechanic who won't diagnose a misfire because there is no CEL is a lazy or inexperienced mechanic. As I mentioned above even a basic OBDII dongle to Carly or other apps can log information that would help pinpoint the issue.
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This car started doing this after a year of owning it. Ordered the car from BMW and i have been the only owner.
No one will touch this car if it doesn't produce a code. Taken the car multiple times to BMW for diagnostics and short of calling me crazy they say that it is normal.
This problem only occurs when the car is warm. When it is cold, it cranks perfectly.
I have done the following;
Cleaned sensors, two pressure sensors and one MAF. Same problem however transmission now shifts more smoothly after doing this.
Checked intake joints for loose clamps. Seems ok but haven't smoked it. Same problem
Change the spark plugs coils and injectors. Same problem.
Tested the fuel rail using ISTA and seems ok. it seems to hold the pressure fine.
Oddly initiated the HPFP with ISTA while the car was off and i could hear that metallic screech sound that i hear along with the misfires. I leaning towards the HPFP now since I discovered this.
every time i do this procedure i can hear the sound although not in the same length or intervals but the same sound nonetheless.