Going rich then lean when shifting
Posted: 2021 May 01, 01:15
The issue is much more prominent when cold but I am still chasing the issue I have been having for years. We have talked about this multiple times and have not been able to figure it out. If I remember correctly. PaulC-Turbo5.0 is also having this same issue with his 94/95 tune.
As a refresher, here is what the car does.
When the car is not warm, when I shift, as the RPMs come down, it goes to about 12.1 AFR, then when I shift, it goes up to 18 or higher. The higher the rpm before I shift, the worse the swing is. If i bring it up to say 5k before I shift, the AFR will drop all the way to 22, the car misfires for a second, then the AFR starts to drop down to normal. After the car is fully up to temp, it does not drop the AFR way down to 22 but I still see AFR of 16-17 when i shift.
Some things I have noticed. During initial startup my car idles at 12 AFR and slowly rises as the car warms up. Once warm, it bounces between 14.3 and 15.5 AFR. Ive played with the enrichment which doesnt seem to change the AFR much at idle when cold. I did change the fuel system out and my fuel trims are a little off even though I set the fuel pressure to 39 with the vacuum disconnected from the regulator. I should have that dialed in over the next day or 2. I drove around today and got them much closer. My idle range maf correction was at 91.9 so it was way off. Im going to lock the car in open loop tomorrow and get idle AFR right at 14.5 after its nice and warm so I have the fuel perfect at idle up to 1000rpm. I would really like to figure out a way to disable the adaptives at idle to 1k if possible. My HEGO is in the down pipe a couple inches from the turbo outlet but it still cools off while idling and I can see the LTFT sway because of long idle times. If I am in a drive thru, (chic fil a takes forever here) its not uncommon for the LTFT to change 8 to 10% which is a huge swing in my opinion.
In the past you had me check a couple things. You asked me to change the time before it goes into closed loop which did not help but unfortunately since we lost the old board DB, I cant go back and find everything I checked.
Is there a Tip in/Tip out setting for fuel that change the way it acts when i get off the gas and press the gas after a shift, kind of like an accelerator pump in a carb? When the car is in open loop after start up, are LTFTs applied or does it ignore them until the car goes into closed loop?
As a refresher, here is what the car does.
When the car is not warm, when I shift, as the RPMs come down, it goes to about 12.1 AFR, then when I shift, it goes up to 18 or higher. The higher the rpm before I shift, the worse the swing is. If i bring it up to say 5k before I shift, the AFR will drop all the way to 22, the car misfires for a second, then the AFR starts to drop down to normal. After the car is fully up to temp, it does not drop the AFR way down to 22 but I still see AFR of 16-17 when i shift.
Some things I have noticed. During initial startup my car idles at 12 AFR and slowly rises as the car warms up. Once warm, it bounces between 14.3 and 15.5 AFR. Ive played with the enrichment which doesnt seem to change the AFR much at idle when cold. I did change the fuel system out and my fuel trims are a little off even though I set the fuel pressure to 39 with the vacuum disconnected from the regulator. I should have that dialed in over the next day or 2. I drove around today and got them much closer. My idle range maf correction was at 91.9 so it was way off. Im going to lock the car in open loop tomorrow and get idle AFR right at 14.5 after its nice and warm so I have the fuel perfect at idle up to 1000rpm. I would really like to figure out a way to disable the adaptives at idle to 1k if possible. My HEGO is in the down pipe a couple inches from the turbo outlet but it still cools off while idling and I can see the LTFT sway because of long idle times. If I am in a drive thru, (chic fil a takes forever here) its not uncommon for the LTFT to change 8 to 10% which is a huge swing in my opinion.
In the past you had me check a couple things. You asked me to change the time before it goes into closed loop which did not help but unfortunately since we lost the old board DB, I cant go back and find everything I checked.
Is there a Tip in/Tip out setting for fuel that change the way it acts when i get off the gas and press the gas after a shift, kind of like an accelerator pump in a carb? When the car is in open loop after start up, are LTFTs applied or does it ignore them until the car goes into closed loop?