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BMW 3-Series (E90 E92) Forum
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Cobb - Fuel Trim / O2 diagnostic help please....
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11-07-2014, 11:56 PM | #1 |
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Cobb - Fuel Trim / O2 diagnostic help please....
I in need of help diagnosing my fuel trim problems for my 07 335i. This is a real tough one to solve. The dealer has given up on this. I have a few idea but would appreciate any feed back on the attached logs. My fuel trim seem to go wild when boost is around -3 to 0 PSI going by the logs but can read to much into this. The are constantly osculating. At WOT the car settle since its in open loop but it on stage 2+ drive map. The logs show the fuel system is good but drops in pressure a bit when fuel trims go +30% so expected. The 02 sensor look just crazy so not sure if this is normal or both are failing at the same time. I am guessing this is the issue. The car should throw a code but trims never stay constant more than a second. The car drives fine and you wouldn't be able to tell there is a probe which is the most frustrating part
So far the over the last two months the following has been serviced: - charge pipe replaced - Tmap & Map sensors replaced - Valve cover and PVC system replaced - Intake system Air leak check with smoke machine and pressurizing (Checked twice now) - Exhaust leak check twice - Vacuum system fully replaced including solenoids - Fuel system diagnostic check - 02 sensor checked for installation and plugged into the right connector The attach picks are: Boost vs. total fuel trim (ST+LT) on Bank 1 Lambda Req Bank 1 vs. Lambda Bank 1 Lambda Req Bank 2 vs. Lambda Bank 2 If anyone has comments on the logs that could help out with this problem it would be much appreciated. I don't have a good baseline to compare the data so comments about this would be helpful. Last edited by Orb; 11-08-2014 at 08:11 AM.. |
02-17-2015, 08:37 PM | #2 | |
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02-26-2015, 07:33 PM | #3 |
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No I don't have one installed . As soon as I figure out the problem I will post it so anyone else that is having this problem will know can get theirs fixed are rule one more thing out
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03-12-2015, 09:47 AM | #4 |
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Yea it is fixed. It was an air leak in thee intake manifold but it got missed even with a smoke test. Check the both intake pressure sensor readings. The intake manifold pressure sensor should be higher in vacuum at ideal and low RPM.
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03-12-2015, 03:48 PM | #5 | |
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