2000redrocket
Pro
Posts: 1662
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posted November 22, 2009 03:27 PM
afr change with temp on power commander or ecu
i have noticed that my bike tuned for a wide open afr of high 12s ends up 13.2 when it is 20 deg colder it seems.
do you guys notice the bikes leaning out with colder weather? i thought the inlet air temp would of kept it closer when the air temp changes.
at 60 deg at my house at 420 ft 3rd gear pull is a nice 12.9 at the track when in low 40s at 200ft it is 13.2 wtf? it was the same difference at 540 ft at maple grove last saturday morning when AA was -150 for the first run and ended up around + 100 to +200 later.
i am thinking on just putting my dobec tuner back on now that i have my afr line fairly flat. and just using that for ritching it up. i can look at the afr all the way down the track when ever i want to where i have it. i will probally hook it up down there.
have you guys noticed this or should i think about replaceing my inlet air temp sensor? i do have something going on when i start it when warmed up it will run lean to 14.5 to 1 for a little bit. the map sensor did not fix it so it has to be the temp sensor i think.
  
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entropy
Moderator
Posts: 8671
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posted November 22, 2009 10:01 PM
2000RR
i have noticed the same issue as you.
tune at one temp, go to a cooler temp and the bike leans out.
I too, thought the airbox temp sensor should work with the ECU and throw more fuel at the motor as the ambient temp gets cooler. Doesn't seem to work that way.
I did replace the inlet air temp sensor, no change I could see.
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tcchin
Zone Head
Posts: 867
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posted November 23, 2009 06:28 PM
That's why I don't use a PC any more.
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2000redrocket
Pro
Posts: 1662
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posted November 23, 2009 06:32 PM
but neither do i and same thing.....
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rtbain
Expert Class
old, fat and slow
Posts: 244
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posted November 24, 2009 03:16 AM
I contacted PC and never got a straight answer. Something like the PC can work in one of two ways. It can modify the ECU signal or use the ECU fuel injector command as a start signal. Modifying the ECU signal takes a faster and more powerful processor.
I suspect the PCIII uses the ECU as a start command. Once initiated it uses its internal mapping to set injector duration. Basically this turns the stock fuel injection into an open loop system unaffected by sensors feeding the ECU.
Open loop systems require adjustment as air density changes. This system is still better than reading plugs and actually changing jets.
I wonder if a PCV can be adapted for use with an aftermarket wide band O2 sensor. Since the PCV seems to have auto tune capabilities it would stand to reason that it is a true closed loop system.
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Randy
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tcchin
Zone Head
Posts: 867
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posted November 24, 2009 10:33 AM
quote:
but neither do i and same thing.....
Are you saying that your stock ECU doesn't compensate for ambient conditions? My Suzuki ECU's have always done a good job of that. From Sears Point in the spring to Pike's Peak and Willow Springs in the summer, the stock ECU map needed no adjustments.
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2000redrocket
Pro
Posts: 1662
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posted November 24, 2009 02:35 PM
well i have it set around 12.9 for a roll on at 400ft 3rd gear like a dyno pull and at the track when it is in the 40s 13.2.
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lar300mag
Parking Attendant
Posts: 17
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posted December 01, 2009 08:02 PM
quote:
I contacted PC and never got a straight answer. Something like the PC can work in one of two ways. It can modify the ECU signal or use the ECU fuel injector command as a start signal. Modifying the ECU signal takes a faster and more powerful processor.
I suspect the PCIII uses the ECU as a start command. Once initiated it uses its internal mapping to set injector duration. Basically this turns the stock fuel injection into an open loop system unaffected by sensors feeding the ECU.
Open loop systems require adjustment as air density changes. This system is still better than reading plugs and actually changing jets.
I wonder if a PCV can be adapted for use with an aftermarket wide band O2 sensor. Since the PCV seems to have auto tune capabilities it would stand to reason that it is a true closed loop system.
I will be home within a week, you can see my PCV with auto tune on the Busa work.
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2000redrocket
Pro
Posts: 1662
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posted December 01, 2009 08:22 PM
it is my under standing things with auto tune just tune a given map over a period of time. you request a afr of 13.0 at map block xy and it sees it is lower or higher. changes the number representing the dwell time and in a couple of hits in that xy it hits the afr and it stays there. i did not here it running real time. maybe under lite loads it would like a car.
iv your pcv is for a busa then it should work.
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