Cat replacement

[crystalworks]

I just replaced my pre-cats on my 4.8is. Going to have to find that fuel adaptation reset menu in the Foxwell.

[ID4.8]

What is this fuel adaptation and what is foxwell? I've never heard of having to do that. Also, I didn't have pre-cats on mine, just the two off the manifolds.

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[EODguy]

The Foxwell is the name of a diagnostic tool. Foxwell NT-510 is a good one to get and you can buy it for less than $200.00 USD and you can read and correct almost any errors in the BMW. Taking the X5 to the stealer for a read and resetting of any error codes (not including parts) can run $200-$400 so it's a wise investment and it can also reprogram some systems/items.

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[crystalworks]

Originally Posted by ID4.8

What is this fuel adaptation and what is foxwell? I've never heard of having to do that. Also, I didn't have pre-cats on mine, just the two off the manifolds.

Sorry, should have been more clear. I meant pre cat o2 sensors.

And what eodguy said regarding the foxwell.

[ID4.8]

So is a fuel adaptation reset something I should have tried? Nobody had ever mentioned that to me before.

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[andrewwynn]

Yes apparently after replacing certain components the computer needs to be told to start over. The long term fuel trims are saved between starts in the DME. I forgot to take a picture of the before values. I had a pretty solid mismatch in short term trim values like one was 5% and one was 2%. They were not large values.

The long term trim however may have changed a lot because those were in milliseconds and may have dropped a decimal! Eg. From 0.02 Ms to 0.005ms.

I'm any event I couldn't believe it was working and check for pending codes every 20-30 minutes on my 90 minutes drive home and no code! Imagine my relief after two weeks of every start getting fuel adaptations lean code about 3 miles into my drive.

INPA software can do the fuel reset but I was sure hoping foxwell could and there is a "reset adaptations" in the DDE module I can't remember if it was in the control or maintenance section but it did the trick.

I'm still not 100% convinced because I only have one long drive since I did the process but after 20+ SES over two weeks and no code for 75 miles drive, combined with a 20-25% bump in mpg (from 19-23) I'm pretty sure that's what it needed.

I'm still getting a small weirdness in the trims (long term neg short term pos) which is said to be an indication of failing MAF which was the next hardware tweak I would be doing.

I will probably swap mine with wife's to see if anything changes.

Some cars will reset DME adaptations by unplugging the fuse in case you didn't have a scanner that can, but I don't know if E53 is one of those cars.

[andrewwynn]

Oh: the primary feedback that chamged was that the post cat sensors would rarely if ever get below half a volt averaging 0.7 or something. Instantly after the reset they would get down to 0.1 for solid seconds at a time and average close to half a volt as I believe they are supposed to.



This was while stopped using on/off throttle to force a swing. Good to see both banks working in unison.

The secondary instant feedback was that the fuel consumption improved hugely: 20-25% improvement! Funny how running lean makes you consume more fuel that's irony for you.

[ID4.8]

I think I'm about to just throw some regular cats back on, not trying to deal with this headache.

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[ID4.8]

Oddly enough, 1k miles later my engine light is now off...

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[crystalworks]

Long road trip? Maybe the truck did it's own adaptation reset? It's nice (and rare) when problems fix themselves.