running lean in Closed Loop...
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,390
Likes: 221
running lean in Closed Loop...
Strange issue: My car runs great and the AFR is pretty much spot on 14.7 (lambda of .94-1.06ish while cruising). However, i'm getting a little knocking of 2-3 degrees during roughly 10-15% throttle at 2500-3500 rpm since the car still wants to hit 1.0 lambda. When I stomp on the go pedal and it drops into PE, I get it commanding .80-.85 and it will not knock while traveling through the 2500-3500 problematic RPM. Is there any way to get my CL to command a richer lamda? Or, are there any other settings I should be adjusting with HPT?
Safety Car
Joined: Nov 2007
Posts: 4,436
Likes: 875
From: Bay Area CA
Strange issue: My car runs great and the AFR is pretty much spot on 14.7 (lambda of .94-1.06ish while cruising). However, i'm getting a little knocking of 2-3 degrees during roughly 10-15% throttle at 2500-3500 rpm since the car still wants to hit 1.0 lambda. When I stomp on the go pedal and it drops into PE, I get it commanding .80-.85 and it will not knock while traveling through the 2500-3500 problematic RPM. Is there any way to get my CL to command a richer lamda? Or, are there any other settings I should be adjusting with HPT?
Last edited by Mike's LS3; Jul 21, 2019 at 11:43 AM.
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,390
Likes: 221
sorry if i was not clear: This is my own tune. Its not tip-in knock because it goes away if I jab it hard. its only there on slow tip in. My LTFT is near zero or -1/-2 at all times so its not enrichening PE. Its perfect at PE (actually, I could probably advance it a bit in PE). Its got a few degrees of KR only while its in closed loop (no PE), and at about 10-15% throttle and mid range RPM. I could fix it by pulling more timing at that non PE area or lowering my PE threshold but I was hoping someone would be able to have a more elegant solution (e.g. enrichen commanded lambda at closed loop? etc.)
Last edited by Ahrmike; Jul 21, 2019 at 11:44 PM.
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
Closed loop, by definition on these cars, can only target lambda=1.00.
I would suggest that you make sure the dyn_air estimate (speed density calculation from the virtual VE coefficients) is spot-on in the part throttle range. This will help avoid most temporary lean holes on tip-in, even if you aren't seeing them on the wideband. Then you can check to see if your spark is appropriate (no more than MBT) in steady state at the same points. Obviously, this is MUCH easier to do on a load bearing dyno than aimlessly driving on the road with no torque readings. You shouldn't need enrichment at light load to avoid knock.
I would suggest that you make sure the dyn_air estimate (speed density calculation from the virtual VE coefficients) is spot-on in the part throttle range. This will help avoid most temporary lean holes on tip-in, even if you aren't seeing them on the wideband. Then you can check to see if your spark is appropriate (no more than MBT) in steady state at the same points. Obviously, this is MUCH easier to do on a load bearing dyno than aimlessly driving on the road with no torque readings. You shouldn't need enrichment at light load to avoid knock.
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,390
Likes: 221
Closed loop, by definition on these cars, can only target lambda=1.00.
I would suggest that you make sure the dyn_air estimate (speed density calculation from the virtual VE coefficients) is spot-on in the part throttle range. This will help avoid most temporary lean holes on tip-in, even if you aren't seeing them on the wideband. Then you can check to see if your spark is appropriate (no more than MBT) in steady state at the same points. Obviously, this is MUCH easier to do on a load bearing dyno than aimlessly driving on the road with no torque readings. You shouldn't need enrichment at light load to avoid knock.
I would suggest that you make sure the dyn_air estimate (speed density calculation from the virtual VE coefficients) is spot-on in the part throttle range. This will help avoid most temporary lean holes on tip-in, even if you aren't seeing them on the wideband. Then you can check to see if your spark is appropriate (no more than MBT) in steady state at the same points. Obviously, this is MUCH easier to do on a load bearing dyno than aimlessly driving on the road with no torque readings. You shouldn't need enrichment at light load to avoid knock.
I also set my stoich AFR to 14.13 to deal with E10 and that seemed to help a bit with this issue but it hasnt removed it fully. I previously had it set at an average of 14.4 (E10/no ethanol).
Burning Brakes
Joined: Jun 2015
Posts: 1,196
Likes: 320
From: Shelbyville Kentucky
Damn. I was hoping I wouldnt have to get into the virtual VE coefficients. I read about it but it seems to be a huge pain with the coefficients vs the table. I guess an air snorkel + custom MAF housing really does affect airflow significantly. I was hoping that changes to the VE would be minimal and as long as I set my MAF curve right it would've been ok. I'll start reading up on it, thanks.
I also set my stoich AFR to 14.13 to deal with E10 and that seemed to help a bit with this issue but it hasnt removed it fully. I previously had it set at an average of 14.4 (E10/no ethanol).
I also set my stoich AFR to 14.13 to deal with E10 and that seemed to help a bit with this issue but it hasnt removed it fully. I previously had it set at an average of 14.4 (E10/no ethanol).
Also was the actual ping or logged data? When I was fooling with this I kept getting strange results. Then I learned there are parameters you need to set to turn off the predictive "ping" in the ECU. Meaning the ECU will try to predict conditions where there might be ping and pull timing. This screws up your data when you are tuning. You only want to see real timing pulls caused by actual ping.
Thread Starter
Drifting
Joined: Dec 2016
Posts: 1,390
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i've been using actual knock retard instead of burst knock. Turns out the new MAF i installed (hitachi) was broken! It was saying my airflow was near max every so often - which i thought was a function of my self made air inlet... Swapped it out for my stock unit and its working mostly fine!
