[Orb]

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.

[JDuke335i]

Originally Posted by Orb

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.

Hey orb did you ever figure out what the problem was ? I have been having the same problem. Trims R all over the place

[JDuke335i]

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

[Orb]

Originally Posted by JDuke335i

Hey orb did you ever figure out what the problem was ? I have been having the same problem. Trims R all over the place

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.

[JDuke335i]

Originally Posted by Orb

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.

Cool , I will check it this weekend. thanks