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Old 01-24-2011, 07:43 AM
kyle540i kyle540i is offline
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Location: greer, sc
Join Date: Jan 2011
Posts: 32
Mein Auto: 98 540i
I am so thankful for all the help this forum has provided. Without it, I might have given up too soon & not been able to fully appreciate this cool car!

I bought my 540i6 from someone who didn't keep any records. He didn't seem to be very mechanically inclined either. He was mostly interested in vanity - he was quick to point out all the cosmetic things he had replaced (cup holders & etc). He wasn't interested in keeping up with the maint. paperwork either.

I had a misfire, and without any documentation, here is what I did towards this problem.

I needed to establish a 'stick in the sand' so I could have a known base line. I did this by buying a code reader & after reading the codes, I cleared them & performed the most basic of tune ups (replaced the valve cover gaskets, spark plugs, plug boot & coils). I still had a misfire & since I had rulled out the coils & spark plugs, I checked for vacuum leaks (none) & I checked the MAF & other intake parts (all clean & looked good/ new).

In the process of this work, I found lots of evidence that led me to believe this has been a recurring issue with this car. I decided to proceed with the assumption that all the obvious items had already been checked or replaced. This led me to think about the process a bit more. Since it idled very smooth & ran well under high intake vacuum conditions, I was looking for causes under higher loads. All I could come up with was poor electrical signal transmission to the injectors & coils. I decided to start at the injector connections. After wiggling the fuel injector elec connector on the offending cylinder, the misfire went away.

Sometimes, we overlook the most basic things. However, after 13 years, the electrical connectors may have just enough oxidation to create an erratic connection.
My plan is to clean all the connectors when the car is down waiting for the pixel repair. In the mean time, I'm driving her every chance I get.
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