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Can't Figure Out Why No Closed Loop

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455 Buick Regal

New Member
Joined
Jul 27, 2014
Messages
26
Helping a friend with his turbo V6 woes. We need to deal with a low fuel pressure problem at the moment (totally unrelated to my question), and then we'll take the next step. But here's my ECU question, thinking one step ahead:

He's running a FAST FXI. I have a log-file in which I thought it should have gotten into Closed Loop, but did not. I also have the Calibration File which I thought would have found the reason why it stayed in Open Loop, but I have not been able to find it.

Asking for any insight...but I can't even figure out how to attach the two files, sheesh!
 
We found out today what the problem was. After-Start-Enrichment-Fuel was preventing Closed Loop. I found that "Aft Corr %" and was >0 and active (decaying). I guess I just needed to wait another 5 minutes or so (too long, in my opinion) to wait for it to end. I need to adjust the "After Start Decay vs CTS" setting (or be more patient!).

There are a couple of places in the FAST documentation that explain Closed Loop prevention during After-Start, and how to find its occurrence on the dash/log file. It just took a while for it to sink into my brain.
 
The newer software, will force the XFI into Closed Loop once you reach WOT
 
Just lower your afterstart decay vs cts settings . I use numbers in the range from 15 cold to about 5 hot, that is just my preference.
 
Perfect, thanks Cal and Norbs.

It's version 1.340

The decay is set way high relative to yours. Thank you for sharing part of your tune (I know they are hard earned learnings and I appreciate it very much).
 
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