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E320 Air Mass Meter

It took my air mass sensor so long to come, that the thread discussing this matter is no longer on my ISP server. So I cannot just tack my result on to a previous message, but I did promise to let those of you who were following this thread know the outcome.

I am happy to report that the air mass meter was the problem. I replaced it with a new one and took the car for a drive of a few miles. I am now getting a report of 18.2 lbs/min of air flow at about 4100 to 4500 RPM. That's about twice what I was getting before at similar RPM's. In addition, the long term fuel trim which was at 34.4% in the freeze frame of data when the check engine light was triggered, dropped to 26.6% over the short trip. After another trip of short distance, the long term trim has dropped to 16.4 and 15.6 % in banks 1 and 2.

In conclusion, putting the new part in and watching the adaptation to better long term trim was certainly the most comforting, but for a do it yourselfer, calculating the equivalent HP for the air flow reported gave me the confidence to order the new air mass meter, an over $200 item.

Thanks to all who helped me along the way to under stand this complicated system.

Dan

To reply directly replace NOSPAM with dubosky in my email address.

Reply to
Dan Dubosky
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Watching the trim come back to norm verifies remedy, but once that is established, the ECU memory should be cleared to get the system back to Mean.. Reason is that while the system is relearning from out of trim specs, other codes can falsely be triggered... By clearing memory, you get back to base line without the wait/drive cycles......

Reply to
AJDalton7

The original thread was only started on December

  1. It is surprising your ISP does not go back that far.

You can get a free news feed at the below address. They go back much farther but they do not carry binaries.

Note that it comes from a German educational institution that is supported by German taxes. Therefore you are helping to support this news server when you buy German products so it is one big happy circle.

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Reply to
greek_philosophizer

Thanks again, AJDalton7. You've been a great help.

The only way that I know how to clear the memory is to disconnect the battery. When I clear the codes, the software says that it also destroys the diagnostic data and the freeze frame data, but I don't think that is what I would call clearing the memory. In fact, if the memory had been cleared as it is when I disconnect the battery, I would think that the long term trim would have started out at zero.

Thanks for the warning about the possibility of getting other false codes. I may just let it go a few days and check it again to see how well it has learned.

Do you have some other way of clearing the memory besides disconnecting the battery?

Dan

Reply to
Dan Dubosky

It just occurred to me that I could also disconnect power to the computer if I could find it. I think that it is near the firewall on the passenger side. Is that correct?

Dan

Reply to
Dan Dubosky

On OBD2 , you have to clear trim memory with a scanner .. disconnecting battery only clears CE lamp diagnostic codes.

Reply to
AJDalton7

Well, in that case, the car is just going to have to learn on its own. I'll deal with the false codes if they should arise.

Dan

Reply to
Dan Dubosky

You should be fine...

For anyone interested, Auto-Zone stores will scan and clear any OBD2 for free.

Reply to
AJDalton7

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