EDIT: Replacement MAF. Not ECU. Gaaaaah.

Still tracking down long crank times when cold, and decided to do some preventive work and swap out the MAF with a generic one for troubleshooting purposes (part matched at least). I know the experiences with non-Denso MAFs have been pretty poor, but this was just done in an effort to see if there was something nuanced about the IAT1 in the MAF that was causing the long crank. another EDIT: 25F start this morning was < 1 sec. Last run was approx. 18 hours ago so fuel drain down would have occurred if check valve.

In replacing the MAF, has anyone experienced different or more deliberate shifting by the transmission? Everything seems fine, but it's revving higher and staying in 2nd and 3rd longer before a lurched shift into the next gear. I have reset the vehicle (via the battery cable method, let it sit) but I didn't want to drive anything extended for fear of causing other issues. No OBD codes. I can always go back to the old MAF- I still haven't pinpointed the long crank. My thinking is that it is still adapting from default profile and relearning based upon a wildly different airflow profile from the new MAF, and that I should give it some time. Thoughts?

 

This is the mercedes gearbox, not the ZF, correct?

 

Correct. 2001 XKR

 

I though the transmissions 'learned' your driving style over a few driving cycles of 15 miles or more.


wj

 

Maybe a small air leak? That would cause higher revs. Fuel trims will show if so.

 

Guys, I just pulled that aftermarket MAF. I was getting WOT readings in the 300s on it via Torque and, unless I've suddenly increased my displacmeent by 2x, those aren't realistic numbers. The reason why it probably cured my long cold crank times was enriching the mixture, albeit falsely. Going back to the old MAF "cured" the weird shifting. In any case, back to the drawing board.

 

You need to disconnect the battery power from the ECM to clear all the adaptations if you want a reading from ZERO trims.
You can disconnect the battery OR pull the ECM fuse for a while to drain the capacitors.
The trims will just pick up where the ECM left off unless you clear the trim adaptions with a BATTERY POWER OFF.(not just ignition off)