Wide band tuning question
08-07-2012, 08:57 PM
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Car: 89 IROC
Engine: 6.8 HSR N2O
Transmission: TKO 600
Axle/Gears: 9" Moser 3.50 True trac
Wide band tuning question
165 6e maf car with HSR intake.
Basic question is~ Should I attempt to keep afr at 14.x at all times when not in PE?
I noticed on tip in acceleration (not PE) my afr will spike to 16-18 for a split second then drop back to 14.x. Should I add AE to eliminate the spike and keep it at 14.x or is a momentary spike normal? It doesn't stumble or hesitate really but does seem smoother at 14.x.
On the other end I noticed the afr will drop to 12-13 when the throttle is closed momentarily. Again, it quickly corrects to 14.x. I have been basically ignoring this end but wondered if I should decel-enlean it here also. Of course the dfco takes it to >22 on hard decel until the fuel comes back on.
Basic question is~ Should I attempt to keep afr at 14.x at all times when not in PE?
I noticed on tip in acceleration (not PE) my afr will spike to 16-18 for a split second then drop back to 14.x. Should I add AE to eliminate the spike and keep it at 14.x or is a momentary spike normal? It doesn't stumble or hesitate really but does seem smoother at 14.x.
On the other end I noticed the afr will drop to 12-13 when the throttle is closed momentarily. Again, it quickly corrects to 14.x. I have been basically ignoring this end but wondered if I should decel-enlean it here also. Of course the dfco takes it to >22 on hard decel until the fuel comes back on.
08-08-2012, 07:13 AM
#2
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Re: Wide band tuning question
Ah yes, the wildly fluctuating AFR, accented by having a stick tranny. As for keeping the AFR in the 14.x range, closed loop will do this for you. So what you are looking for is as little fuel trim correction as possible (BLM).
As for AE, also look a the INT. A little bit of an INT increase on AE is OK. As long as as you noticed that there isn't any stumble. Can add a bit more at a time to reduce the lean spike, but never so much that the INT drops from AE.
A falling INT will cause a lean sag as the AE runs out.
DE, increase it to get rid of the richness, but not too far. Too much DE and when you get back on the go-pedal there won't be enough AE and you'll get a lean sag.
These areas will never be perfect. It is more about driveability.
RBob.
As for AE, also look a the INT. A little bit of an INT increase on AE is OK. As long as as you noticed that there isn't any stumble. Can add a bit more at a time to reduce the lean spike, but never so much that the INT drops from AE.
A falling INT will cause a lean sag as the AE runs out.
DE, increase it to get rid of the richness, but not too far. Too much DE and when you get back on the go-pedal there won't be enough AE and you'll get a lean sag.
These areas will never be perfect. It is more about driveability.
RBob.
08-08-2012, 05:53 PM
#3
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Car: 89 IROC
Engine: 6.8 HSR N2O
Transmission: TKO 600
Axle/Gears: 9" Moser 3.50 True trac
Re: Wide band tuning question
Ah yes, the wildly fluctuating AFR, accented by having a stick tranny. As for keeping the AFR in the 14.x range, closed loop will do this for you. So what you are looking for is as little fuel trim correction as possible (BLM).
As for AE, also look a the INT. A little bit of an INT increase on AE is OK. As long as as you noticed that there isn't any stumble. Can add a bit more at a time to reduce the lean spike, but never so much that the INT drops from AE.
A falling INT will cause a lean sag as the AE runs out.
DE, increase it to get rid of the richness, but not too far. Too much DE and when you get back on the go-pedal there won't be enough AE and you'll get a lean sag.
These areas will never be perfect. It is more about driveability.
RBob.
As for AE, also look a the INT. A little bit of an INT increase on AE is OK. As long as as you noticed that there isn't any stumble. Can add a bit more at a time to reduce the lean spike, but never so much that the INT drops from AE.
A falling INT will cause a lean sag as the AE runs out.
DE, increase it to get rid of the richness, but not too far. Too much DE and when you get back on the go-pedal there won't be enough AE and you'll get a lean sag.
These areas will never be perfect. It is more about driveability.
RBob.
And I see your point on DE. Will do.
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