Lonnies Performance
December 15th, 2023, 03:32 PM
I am having an issue with the vehicle initially going lean in closed loop.
This is an LSA supercharged 6.2 in my S10 with the factory 411 PCM.
Upon initial start the air fuel is 11.5 which tapers to 13:1 as it starts to warm up according to my wideband.
It appears the STFT initially pulls fuel & as soon as the transition to closed loop happens, the LTFT's ramp pulling a ton of fuel (to their set limit) until the wideband reads close to 19:1. After a short time the LTFT's are back to normal at a negative 1 or 2% where I want them.
This only happens at cold start & usually is when pulling from a stop through an intersection where drivability is critical.
If I get the vehicle moving before closed loop, it only shows up as a hesitation for a few seconds.
I've tried altering the closed loop temp & time delay, but it still does the same thing, it just takes longer.
I can reduce the LTFT limits, but I should not have to do this.
If I make the values in table B3647 1's the problem goes away, but with a manual trans it likes some additional fuel during warm up.
The values in this table are around 7.-.85 in most stock 411 computers.
Can I no longer use this table in this manner?
Is there something different I should be doing?
Otherwise it starts, drives & runs great.
Thanks for any help you can provide.
This is an LSA supercharged 6.2 in my S10 with the factory 411 PCM.
Upon initial start the air fuel is 11.5 which tapers to 13:1 as it starts to warm up according to my wideband.
It appears the STFT initially pulls fuel & as soon as the transition to closed loop happens, the LTFT's ramp pulling a ton of fuel (to their set limit) until the wideband reads close to 19:1. After a short time the LTFT's are back to normal at a negative 1 or 2% where I want them.
This only happens at cold start & usually is when pulling from a stop through an intersection where drivability is critical.
If I get the vehicle moving before closed loop, it only shows up as a hesitation for a few seconds.
I've tried altering the closed loop temp & time delay, but it still does the same thing, it just takes longer.
I can reduce the LTFT limits, but I should not have to do this.
If I make the values in table B3647 1's the problem goes away, but with a manual trans it likes some additional fuel during warm up.
The values in this table are around 7.-.85 in most stock 411 computers.
Can I no longer use this table in this manner?
Is there something different I should be doing?
Otherwise it starts, drives & runs great.
Thanks for any help you can provide.