changing stoichiometric AFR
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From: Lengede
changing stoichiometric AFR
If I change the stoichiometric AFR from 14.7 in the constants table to let's say 14.0, would this mean I would be running richer throughout the whole rpm range, except when running WOT???
Drifting
Joined: Nov 2009
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From: Perth Western Australia
St. Jude Donor '10
Sounds right. Used as the reference for closed loop mode.
Open loop is not just at WOT though. On start up open loop mode is activated until the o2 sensor warms up.
Open loop is not just at WOT though. On start up open loop mode is activated until the o2 sensor warms up.
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From: Lengede
I think I might try it out today or tomorrow. I was running OL, then decided to try CL but with 14.7 AFR it's just too lean for my engine. See if 14.0 AFR will help, hope both of us are right. Maybe someone will chime in that has tried it out first hand.
Yes, I know that OL isn't just for WOT. It is activated through "min cool temp. for closed loop" in my case.
Yes, I know that OL isn't just for WOT. It is activated through "min cool temp. for closed loop" in my case.
Drifting
Joined: Nov 2009
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From: Perth Western Australia
St. Jude Donor '10
As its 12:1 in open loop mode I can't see how going from 14.7:1 to 14:1 is going to cause you any engine damage. If you were going the other way then yes you could do some damage.
How have you concluded that 14.7 is too lean for your engine?
How have you concluded that 14.7 is too lean for your engine?
Last edited by Lemme; Aug 13, 2010 at 07:14 AM.
Burning Brakes
Joined: Apr 1999
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From: Cumming GA
I think I might try it out today or tomorrow. I was running OL, then decided to try CL but with 14.7 AFR it's just too lean for my engine. See if 14.0 AFR will help, hope both of us are right. Maybe someone will chime in that has tried it out first hand.
Yes, I know that OL isn't just for WOT. It is activated through "min cool temp. for closed loop" in my case.
Yes, I know that OL isn't just for WOT. It is activated through "min cool temp. for closed loop" in my case.
If it is stumbling Riching it will smooth it out, but so will advancing the timing.
With my BS3 ECM, My a/f 14.7 and the it bounced between 14.5 and 15.2 with various degrees of timing depend where I am on the Map table. This is not going to hurt anything as it is not build the heat in the cylinder to damage ring landings or piston. BTW my cam was a 254/254 on a 112lsa
Now when I tip in I drop to 12.5 and the timing is 1 degree less then detonation at each kpa/rpm
My response is check the timing when your at 14.7, you'll get better mpg, it just takes a little more work with your cal to work out all the kinks
John
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From: Lengede
Sorry to get back to you so late, but I have other problems at this time and these have to be fixed first.
Once you get to above >2500 rpm 14.7 AFR is fine. One could even go much leaner, but below <2500 rpm you just have to run richer, and of course run a little more timing. BTW, I'm running from 1600-2000 rpm 37°-42° and from 2000-2800 rpm 39°-43° at part throttle. I don't run my engine below 1800 rpm though.
I'm using my stock '92 ECM with MAP. Since I can't richen up the mixture other than running OL, I thought I could set my stoichiometric AFR to let's say 14.0
I wouldn't mind running this rich even at higher rpm at part throttle.
Once you get to above >2500 rpm 14.7 AFR is fine. One could even go much leaner, but below <2500 rpm you just have to run richer, and of course run a little more timing. BTW, I'm running from 1600-2000 rpm 37°-42° and from 2000-2800 rpm 39°-43° at part throttle. I don't run my engine below 1800 rpm though.
I'm using my stock '92 ECM with MAP. Since I can't richen up the mixture other than running OL, I thought I could set my stoichiometric AFR to let's say 14.0
I wouldn't mind running this rich even at higher rpm at part throttle.
