Question for guys running an open loop tune
05-08-2006, 07:17 AM
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Question for guys running an open loop tune Well not really a problem but................it's got me doing this 
2000 Formula race only, LS1 heads/cam, auto, 12 bolt/spool
Open loop tune.
While racing Saturday I noticed something that has me a little worried.
At 1878' DA on a 1.56 sixty foot I ran a 11.325 at 118.59
At 800' DA on a 1.53 sixty foot I ran a 11.312 at 118.
At 700' DA on a 1.53 sixty foot I ran a 11.314 at 118.
Now I know that this is an open loop tune but I still figured that the car was reading the IAC and MAF so it would change the calibration based on the amount of air and the air temp. If it ran 11.32@118.59 at 1878' it should have run almost 11.20-1@120 at 700'
I'm confused and a little worried. If it doesn't compensate for cooler air then it's not going to compensate for hotter air either. If it doesn't compensate for hot air then when I go to the track and it's 90° out and the DA is 3500 feet it's going to knock like hell and maybe even break something.
Or is it just not sensitive to DA anymore and I need to track VP or dew point?
Somebody please help me understand what's going on.
2000 Formula race only, LS1 heads/cam, auto, 12 bolt/spool
Open loop tune.
While racing Saturday I noticed something that has me a little worried.
At 1878' DA on a 1.56 sixty foot I ran a 11.325 at 118.59
At 800' DA on a 1.53 sixty foot I ran a 11.312 at 118.
At 700' DA on a 1.53 sixty foot I ran a 11.314 at 118.
Now I know that this is an open loop tune but I still figured that the car was reading the IAC and MAF so it would change the calibration based on the amount of air and the air temp. If it ran 11.32@118.59 at 1878' it should have run almost 11.20-1@120 at 700'
I'm confused and a little worried. If it doesn't compensate for cooler air then it's not going to compensate for hotter air either. If it doesn't compensate for hot air then when I go to the track and it's 90° out and the DA is 3500 feet it's going to knock like hell and maybe even break something.
Or is it just not sensitive to DA anymore and I need to track VP or dew point?
Somebody please help me understand what's going on.
05-08-2006, 11:57 AM
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Oxygen sensors are not even used during pe/wot so I don't think open loop itself is the route of your problem. Also, it'll be more likely to knock during colder temps as air becomes denser packing more 02 in the chamber hence requiring more fuel. Unless ofcourse your cooling system is having a problem keeping the motor's temperature at bay which will also cause knock if the motor itself gets too hot.
05-12-2006, 07:49 AM
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Originally Posted by DAPSUPRSLO
Oxygen sensors are not even used during pe/wot so I don't think open loop itself is the route of your problem. Also, it'll be more likely to knock during colder temps as air becomes denser packing more 02 in the chamber hence requiring more fuel. Unless ofcourse your cooling system is having a problem keeping the motor's temperature at bay which will also cause knock if the motor itself gets too hot.
05-14-2006, 08:03 AM
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Originally Posted by mvonada
Did you calculate DA right. Going from 1878 to 800 is a big drop in temp. Do you know what the temps were on your runs?