New battery & Alternator causing Trans. Failsafe Prog

[mcfee03]

I just installed an Siemens MAF, and the trans failsafe is gone.

I cleared the faults using my ODB 2 tool.

The x5 still drives horribly. Flat acceleration, putters in what feels like second gear.

The code im getting now is a P0174- Power train warning (system too lean, Bank 2).

What should I be doing next? Does my new MAF need to be calibrated or setup in any way?

[upallnight]

P0174 mean the engine is running lean. You could have a vacuum leak after the MAF or a weak fuel pump. If you can I would look at Live Data, short term and long term fuel trims in both banks, as well as the 02 sensor voltage pre-cat.

[andrewwynn]

Will power restore when you clear the MIL? Does the transmission actually shift? When engine is in safe mode it feels like 2 cylinders.


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[bcredliner]

MAF is simple plug and play, no setup or calibration procedure.

It sounds like engine is in limp mode. If so, acceleration will be terrible, engine will sound like it is roaring and transmission will always be in 4th gear. Engine in limp mode means the computer thinks something is wrong that will damage the engine or transmission. A problem that causes limp mode will generate error codes that diagnostics will read.

If you bought a used MAF it could still be the problem even though trans failsafe mode is gone. Current symptoms can be caused by bad MAF. I suggest returning to Indy and have him see if the MAF has been eliminated as the cause of your problem. Does Indy specialize in working on BMWs?

I can't imagine how frustrated you are. It does appear you have made progress toward the solution. Hang in there. Stay focused on following the diagnostic indicators.

[andrewwynn]

When I get a misfire apparently related to coil just starting to fail I get limp mode that stays until I reset. P0174 sounds familiar like what I got with failing CPS but that one never caused limp mode.

Limp mode will feel like constant misfire with chugga chugga and no power but it will shift. If some how trans is in fail safe just without the visible indicator the engine can be running fine no chugga just stuck in 4th gear so virtually no acceleration at all.


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[bcredliner]

Failsafe and limp mode are the same thing. Engine will roar, transmission is locked in 3rd or 4th gear and acceleration is extremely poor.

[upallnight]

Since you got the P0174 after you installed the MAF, I would look to see if maybe the MAF is installed correctly. By that I mean the large o-rings or rubber seal hasn't roll under as you installed the MAF and is now causing an air leak. I like to use dishwasher liquid when I do that to prevent the seal from rolling under. If you removed the rubber boot to the throttle plate I would revisit that installation as well and use the liquid dishwasher trick to get the boot back in. Don't use any oil as oil will eventually ruin the rubber.

[andrewwynn]

I've caught that exact problem when installing MAF as it turns out saliva will work in a pinch.


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[upallnight]

Originally Posted by andrewwynn

I've caught that exact problem when installing MAF as it turns out saliva will work in a pinch.


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Ewwwwwwwwwww!!!!

[andrewwynn]

Next time I would use wiper spray. Less eeeew but readily available. The o-ring should be oil resistant but not the intake boot. And to think I self moderated to avoid the word 'spit'.


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