Originally Posted by
neildavid
Hey, been reading the forums for years. So far I have been able to search and find solutions to problems I have come across thanks to the threads on this site. But not this time, so I had to make an account to ask.
Ok, so I have a 2003 325i. It hesitates and will idle rough, acting like it has a vacuum leak. I ran a scan tool on it in generic mode and the fuel trim long % is 8.3 in bank 1, and 9.4 in bank 2. I don't know what the threshold is on these readings but It looks like there is a problem. I examined intake boots and vacuum lines and couldn't find any cracks. I ran a smoke test through the entire intake and ccv lines. I couldn't find anything. I also sprayed brake cleaner all over and still nothing. The ccv was replaced on this car acouple of months prior.
I also have a 2005 Z4 3.0i that is butter smooth, and runs like it has no problems what so ever.
I ran the scan tool on it to compare the readings and was surprised to see that my fuel trim was 11.7 in bank 1 and 9.8 in bank 2. I ran the same tests as before and found no leaks. Both cars have suction when removing the oil cap.
Has anyone run into similar readings and symptoms? I don't understand how the z4 has no symptoms yet higher fuel trim %. Any help would be greatly appreciated.
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