AF Ratio on Throttle off
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 56
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AF Ratio on Throttle off Just out of curiousity do I need to be concerned too much about the AF ratio when you come off the throttle. I was driving and logging the tune and noticed that when I let off the throttle to come to a stop from 3500-4000 rpm and the rpms decrease back to idle, the AF ratio goes up to 15.7 - 16.3. Is this a major issue or not a huge concern. I'm going to have my tuner finalize the tune for regular driving but I didn't know if I should not run the motor at all the way it is.
Also what should the AF ratio be at idle. Should we try for the 14.7 or something higher to reduce fumes and such?
Thanks,
Adam
Also what should the AF ratio be at idle. Should we try for the 14.7 or something higher to reduce fumes and such?
Thanks,
Adam
TECH Enthusiast
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From: Denver International Airport, Colorado USA
I probably would not be too concerned about it. There is very little load on the engine at the point. In fact a lot of PCM's use DFCO. It shuts down injector flow and spark as you decel.
But, you have to be your own judge on it. Some cars/owners might prefer richer for various reasons (bucking, etc..).
As far as idle I've done fine on 14.7-15.5 AFR's. As one poster indicated, closed loop attempts to get you to 14.7 anyway, but you sound like you have a different setup. Richer than 14.0 I start bogging, leaner than 16.0 (a few hot re-starts), it starts getting choppy and stumbles.
Also be aware of the surrounding idle cells, especially at higher MAP and even the 400rpm row. If you start stalling and it hits a cell that is not dialed in (usually richer), expect to stall.
Those are my thoughts. Hope it works out for you.
..WeathermanShawn..
But, you have to be your own judge on it. Some cars/owners might prefer richer for various reasons (bucking, etc..).
As far as idle I've done fine on 14.7-15.5 AFR's. As one poster indicated, closed loop attempts to get you to 14.7 anyway, but you sound like you have a different setup. Richer than 14.0 I start bogging, leaner than 16.0 (a few hot re-starts), it starts getting choppy and stumbles.
Also be aware of the surrounding idle cells, especially at higher MAP and even the 400rpm row. If you start stalling and it hits a cell that is not dialed in (usually richer), expect to stall.
Those are my thoughts. Hope it works out for you.
..WeathermanShawn..
Thread Starter
Staging Lane
Joined: Mar 2006
Posts: 56
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Thanks for the info Mr Weatherman. I will see what I can do to get this thing running well. I have been driving it around my neighborhood and it seems to be running very well. Just a few more tweaks and we shoudl be set.
Adam
Adam
