540i Touring Intake Temps and Lean Error?

[spngr311]

I seem to get a problem with my 540iT. I get a lean condition (trims go lean, eventually get a lean error) and a loss of power if I am driving in traffic during hot weather. I notice my intake temps climbs to 175*f. What could cause the performance issues? Is it related to the Dinan tune? I have replaced a good portion of anything related to it (maf, o2 sensors, filter, etc.), verified I do not have any intake leaks, and am starting to run out of options. It only gets me during long trips when you get off the interstate and then get bogged in traffic.

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[scottieducati]

By filter I presume fuel? Also have you done fuel pump? I highly recommend sending out your injectors for a service. They do gum up especially with sugar in our fuel.


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[spngr311]

I replaced the air filter, fuel filter, and fuel pump. I replaced the o rings on the injectors, but not the injectors.

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[blarf]

Interesting. I've struggled with the 540 running lean (but not usually lean enough to set the MIL) and hesitating under part load acceleration for a while. If you look at the Dinan MAF tube there's no screen (Bosch advises its OEMs to use a screen). I've put the stock MAF tube (which is as big as a 996 turbo's and has a screen BTW) back in place and changed out the plugs (which, while old, looked mostly serviceable at 120k miles). Haven't had a chance to drive the car much, but it seems improved especially when cold. INPA is reporting negative fuel trims (car is running rich) but closer to normal than with the blingy Dinan tube.

My money is on the Dinan parts being garbage.