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Old 05-07-2019, 02:39 PM
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andrewwynn andrewwynn is offline
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Location: Racine, WI
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I'm having very similar situation with car running too lean.

My theory is that some component is feeding a slightly incorrect number into the computer. It's subtle enough the computer gives the misbalance "pass" waiting for the bad tank of fuel etc. to work itself out.

I suspect the MAF or pre cat O2 in my case but it can be a worn out capacitor in the ECM.

When I look at my fuel trims they are constantly high but not crazy high say 7% but always. Never 2% never negative. The computer probably takes an integral of the fuel trim and if always positive like my case it will only get bigger. It simply has to have some threshold that trips it.

Now for me here's a twist: I didn't have my scan tool with the last time my SES came on and after two days it did the unimaginable thing of clearing itself. I'm very curious to see if my trims worked themselves out. The computer should know over time to make a long term fuel trim to get short term to be close to zero so maybe mine finally worked out the kinks.
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E53 / M54 2001 3.0i gas LHD (pair of them: his & her)
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