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2001 330xi 208k
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145 Posts
Discussion Starter · #21 ·
@NZ00Z3

Second round of logs available now. The only thing I changed that's material was the rear O2 sensor (Bank 2 pre-cat, per instructions).

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I did not clear the SES or anything. I don't know how long it takes for the trims to reset or if they need to be. What else do I need to do?

I'm not 100% confident that Bank 1 O2 sensor is perfect but that's from cursory glances at the Fusion dashboards while driving.
 

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Z3's 3.0L and 2.8L
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2,640 Posts
Another set of good logs. Thank you.

Here is my updated analysis file: 20221120 2001 330iX Idle Problems- Swooshdave.xlsx

Both pre-cat O2's are now working well, there is no fuel system status faults anymore. Well done.

A couple of thing s to look at:
  • Check the SAP system. Make sure that you do not have a hole in a rubber hose or that the metal valve is leaking. In the Cold Start Pre-cat O2's chart, I can see the O2 sensors heat and go lean while the SAP is running. When the SAP turns off (Command secondary air goes to 4), the O2 sensors should go rich. They are not. They stay lean and the fuel trims show around 17% lean. A leaking SAP will cause lean fuel trims.
  • If you haven't smoke tested the engine for vacuum leaks, then do it. Cruise fuel trims are great. Hot idle fuel trims are on the upper margin. This indicates a small vacuum leak somewhere.

You always have the option of, if it's not popping any codes, then drive it like you stole it.

Time Invested
It took a little over an hours to spread sheet your logs and write up this post.
 

· Registered
2001 330xi 208k
Joined
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145 Posts
Discussion Starter · #23 ·
Another set of good logs. Thank you.

Here is my updated analysis file: 20221120 2001 330iX Idle Problems- Swooshdave.xlsx

Both pre-cat O2's are now working well, there is no fuel system status faults anymore. Well done.

A couple of thing s to look at:
  • Check the SAP system. Make sure that you do not have a hole in a rubber hose or that the metal valve is leaking. In the Cold Start Pre-cat O2's chart, I can see the O2 sensors heat and go lean while the SAP is running. When the SAP turns off (Command secondary air goes to 4), the O2 sensors should go rich. They are not. They stay lean and the fuel trims show around 17% lean. A leaking SAP will cause lean fuel trims.
  • If you haven't smoke tested the engine for vacuum leaks, then do it. Cruise fuel trims are great. Hot idle fuel trims are on the upper margin. This indicates a small vacuum leak somewhere.

You always have the option of, if it's not popping any codes, then drive it like you stole it.

Time Invested
It took a little over an hours to spread sheet your logs and write up this post.
Thank you again! Yes, I saw the hot idle fuel trims and thought they were high.

Doesn't the SES get triggered at 25%?

Am I safe to clear codes or some other sort of reset?

When I got the car all three of the SAP mounts were broken. I replaced them. I'm not sure what could have broken them, perhaps age and heat being near the headers. But I will check all of the hoses in the area.

Yes, smoke test is in my future. And suspension bushings. And motor mounts. Luckily I like working on this thing.
 

· Premium Member
Z3's 3.0L and 2.8L
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2,640 Posts
Clear the codes and reset the adaptions as needed.

The fuel system deviation codes pop when the fuel trms exceed 10% for a predetermined time (can't remember the time).

If it's not popping codes, then enjoy driving it and tinkering with it.
 

· Registered
2002 330i auto
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279 Posts
The fuel system deviation codes pop when the fuel trms exceed 10% for a predetermined time (can't remember the time).
I think this depends if the car is MS43 or MS45. My car ran at +24% STFT continuously without codes while I was troubleshooting. In certain conditions it would exceed 26% and then throw a code instantly.
 

· Registered
2001 330xi 208k
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145 Posts
Discussion Starter · #28 ·
Clear the codes and reset the adaptions as needed.

The fuel system deviation codes pop when the fuel trms exceed 10% for a predetermined time (can't remember the time).

If it's not popping codes, then enjoy driving it and tinkering with it.
I did a search and haven’t found out how to reset the adaptations yet.
 
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