rich AFR after decel

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
PaulC-turbo5.0
Posts: 83
Joined: 2021 Feb 15, 21:56
Location: Lancaster New York
Vehicle Information: 1989 fox GT convertible
5.0 stock block, E7 heads, stock cam
Explorer GT40 intake flipped to driver side inlet
Single 67mm On3 BB turbo
Flipped JBA headers, custom SS 2.5" hotside built by me
custom 3" coldside thru On3 intercooler
tuning with Moates QH + TPRT
Dechipa's GUFX and supporting files, couldnt have tuned it myself without him!

rich AFR after decel

Unread post by PaulC-turbo5.0 »

anytime I go into decel in closed loop the AFR coming out is rich, the longer the decel the richer the AFR. Is there anything I can adjust to try to help out with this?
Apex
Posts: 6
Joined: 2021 Jul 26, 13:52
Location: Denver, CO
Vehicle Information: 1998 Ford Escort ZX2
1996 Ford Mustang
2007 Ford F-150

Re: rich AFR after decel

Unread post by Apex »

On the mechanical side are you possibly pulling in oil vapors from leaking valve seals, stuck open PCV valve, or fuel vapors from a stuck open EVAP purge solenoid or other extraneous fuel source? This would be most prevalent under high vacuum.

My other guess on the tuning side would be if the computer is learning closed loop fuel adjustments under decel when the AFRs would be leanest, but don't listen to me I still have a ton to learn. Is your pedal position status going into dashpot on decel? I would imagine but can't say for sure this should tell the ECU not to learn fueling during decel. Perhaps Decipha or anyone with more knowledge than myself can say if I went off on the wrong trail.
PaulC-turbo5.0
Posts: 83
Joined: 2021 Feb 15, 21:56
Location: Lancaster New York
Vehicle Information: 1989 fox GT convertible
5.0 stock block, E7 heads, stock cam
Explorer GT40 intake flipped to driver side inlet
Single 67mm On3 BB turbo
Flipped JBA headers, custom SS 2.5" hotside built by me
custom 3" coldside thru On3 intercooler
tuning with Moates QH + TPRT
Dechipa's GUFX and supporting files, couldnt have tuned it myself without him!

Re: rich AFR after decel

Unread post by PaulC-turbo5.0 »

I dont think its mechanical because I just noticed while still in OL the other day it didnt do it. I have a feeling its the ECU trying to compensate for the lambse ramping lean while in decel but not 100% sure which is why I posted, I am still always learning myself.
PaulC-turbo5.0
Posts: 83
Joined: 2021 Feb 15, 21:56
Location: Lancaster New York
Vehicle Information: 1989 fox GT convertible
5.0 stock block, E7 heads, stock cam
Explorer GT40 intake flipped to driver side inlet
Single 67mm On3 BB turbo
Flipped JBA headers, custom SS 2.5" hotside built by me
custom 3" coldside thru On3 intercooler
tuning with Moates QH + TPRT
Dechipa's GUFX and supporting files, couldnt have tuned it myself without him!

Re: rich AFR after decel

Unread post by PaulC-turbo5.0 »

just to update this I adjusted hego delay fn1351 out to 20 in all cells and it has helped quite a bit, the base tune I started with had this table populated with lower numbers. I went the wrong way at first and the lambses were switching super fast lol and once I realized and went to all 20's it settled them down nicely.
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