Quote:
Originally Posted by kchilaka
Folks,
I spent a good hour searching through the forums on what my symptoms could mean (search yielded coils, vacuum leak and/or plugs) so I have not been lazy before I posted this. I was hoping to get some feedback on what my car symptoms could be.
I have a 2007 BMW N54 335i Sedan with 115k miles on it. About a couple of months ago, my car began having a rough misfiring idle (like it was going to stall) when I started my car. I am pretty sure the rough idle happens everytime I start my car after it has sitting for 3-4 hours. Engine might still be pretty warm in 3-4 hours so I dont know if this is classified as a cold-start condition but those are the parameters under which this occurs. If I give it a little gas (rev past 2k rpm), the engine completely smooths out and once I get driving the rough idle/misfire goes away completely. Power on the highway is normal and after the car has been running for a few minutes, I can idle the car just fine. The problem happens only during start.
Another thing to note: NO Check Engine light.
My plugs were replaced last year and have less than 10k miles on them so I am reasonably confident the issue is not with my spark plugs especially because the misfire does not happen under load.
There is no hesitation during the actual starting of the car (it fires right up to a rough idle) so I am tending to think this is not a HPFP issue. My HPFP was last replaced 2 years ago with the latest BMW part number.
Right now I am thinking clogged/bad injectors(i did run the car to nearly empty on the fuel tank once) or coils (not been replaced for a few years) or perhaps my battery. My battery is on it's last legs and it is possible it is losing charge in the few hours the car sits before I start it and once the car gets going the alternator is able to power the coils (this is a wild guess as I am not sure how effective the alternator is at idle speeds).
I have not pulled codes using a BMW reader, although I did buy an INPA USB-OBD2 cable. The software setup seems very time consuming just to read diagnostic codes (i don't ever plan to code the car).
Does anyone have suggestions on what it could be. I know eventually I will have to take it to someone in the baltimore area to get it scanned but I am trying to have a reasonable understanding of the problem.
Thanks for reading this lengthy post.
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Free mhd app would be quite suitable and very easy to read codes, uses the cable but needs usb to micr usb adapter.