Fuel Trim Malfunction (Bank 2) '98 740i

[gmateer]

My car is starting rough when it sits for a while, either overnight or after a vacation where it has been sitting in the garage.

The fault code says that there is a "Fuel Trim Malfunction (Bank2). Any thoughts of what might cause this? I recently replaced the fuel filter and noticed some (small) cracks in the line connectiing the fliter.

Thanks for any guidance that you might be able to give me to rectify this issue.
gbm
'98 740i Blue w/ Grey

[michael murray]

i have the same problem with my 2001 mercedes c240. when i scanned my car the same exact malfunction came up. the thing that makes me wonder is that i also just recently changed my fuel filter also. i haven't yet bought the "chilton's" book on this car, so i haven't had a chance to further investigate the matter, but my car is idling very rough. let me know if you have some information that i don't. thanks, and good luck.

mike

[davshanks]

I have a fuel trim malfunction for several months. My mechanic said its either a leaky intake manifold gasket or the MAF sensor. Probably the MAF sensor in my case because it shows bank 1 & 2. No symptoms of running rough.

[Ebellanca]

I would start with a intake manifold reseal and vent valve on the back of the intake. Also dont forget to replace the gasket on the throttle housing. Good luck

[CD]

Had the same codes/problem. Replaced the throttle body to intake manifold gasket and it cured it. Replaced plugs and valve cover gaskets while I had the cover,etc. off.
Hopes this helps.

CD
1998 740IL

[Joe Z]

Codes reveal that there are multiple missfires and bank 1 and bank 2 fuel trim problems.

I have replaced the fuel filter, fuel pump, and the rear intake plate and gasket (did not remove the intake manifold). This car still runs smoothly except when cold but even then it runs okay. If there is an air leak it would seem that it would have to be at either the rear of the intaked manifold or the front since both banks are involved. The MAF may be suspect but not sure how to check it. The other thing that has occured since installing the new fuel pump is a strong gas ordor that seems to be coming from the engine compartment. A visual inspection does not detect any noticable leakage. Any help will be welcomed.

[Car prob]

[brian h]

i had the same exact problem, guess what. its your gas tank. its got a leak also chech the hose into the gas tank it may be pinched or leaking!

[TUmoFYQQjOgHz]

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