ECU feeback compensation ...
03-05-2006, 11:42 AM
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ECU feeback compensation ...
Ok, ever since I installed my S/C and intake I have noticed that pushing the gas pedal 100% is not the most effective way to proceed down the highway, there is a "sweet spot" at about 80%, I found this through the wierd sensation that ensues after flooring the gas and then letting off, as I let off there would be a noticable acceleration boost.
I first noticed this back when I had my G35 sedan with blitz intake and this side-effect has shown up again on my Stillen'd coupe ...
According to SGP's site this is a feature of our ECU ...
"Changed air intake system One of the major problems on this car was a feedback system that compensates for modifications. The oxygen sensors detects fuel mixture and will tell the ECU to richen up or lean out the mixture. This correction factor was way too wide, so some performance components upgrades (intake, exhaust) would actually result in a loss of HP below stock! We adjusted the correction factor to reduce that compensation reaction."
My question (and yes there is one) is, how many other FI'd drivers (as I don't believe this is an issolated case) are experiencing this and what our the professionals' opinions???
Because (and correct me if I'm wrong) if the ECU is compensating in such a manner, then I am not getting the full potential out of my engine.
How is it doing it, is it closing the throttle or as SGP state is it changing the fuel mix ... either way, it is making my car a b*tch to drive well under 'spirited' conditions as trying to find that 'sweet spot' in the heat of the moment is not easy.
Thanks in advance,
Colin
I first noticed this back when I had my G35 sedan with blitz intake and this side-effect has shown up again on my Stillen'd coupe ...
According to SGP's site this is a feature of our ECU ...
"Changed air intake system One of the major problems on this car was a feedback system that compensates for modifications. The oxygen sensors detects fuel mixture and will tell the ECU to richen up or lean out the mixture. This correction factor was way too wide, so some performance components upgrades (intake, exhaust) would actually result in a loss of HP below stock! We adjusted the correction factor to reduce that compensation reaction."
My question (and yes there is one) is, how many other FI'd drivers (as I don't believe this is an issolated case) are experiencing this and what our the professionals' opinions???
Because (and correct me if I'm wrong) if the ECU is compensating in such a manner, then I am not getting the full potential out of my engine.
How is it doing it, is it closing the throttle or as SGP state is it changing the fuel mix ... either way, it is making my car a b*tch to drive well under 'spirited' conditions as trying to find that 'sweet spot' in the heat of the moment is not easy.
Thanks in advance,
Colin
03-05-2006, 01:05 PM
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I would imagine that only happens when the car is in closed loop operation - in the very low load ranges. Since the 2003-04.5 all have narrowband 02 sensors, they would not be capable of adjusting in the high load sites. Not sure if the 04.5+ Z's are any different with their widebands.
03-05-2006, 01:17 PM
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Originally Posted by ht4
I would imagine that only happens when the car is in closed loop operation - in the very low load ranges. Since the 2003-04.5 all have narrowband 02 sensors, they would not be capable of adjusting in the high load sites. Not sure if the 04.5+ Z's are any different with their widebands.
Colin
03-05-2006, 01:43 PM
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I could be totally off on this but , I believe you are just going from open loop to closed loop . And when you let off the gas a little the SS box is no longer in full control of fuel and timing . In the upper boost and rpm range , the SS box pulls a bunch of timing and adds a bunch of fuel . So when you let off the gas , the ECU starts to lean it out some and you feel a gain in power .
03-05-2006, 02:55 PM
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Originally Posted by booger
I could be totally off on this but , I believe you are just going from open loop to closed loop . And when you let off the gas a little the SS box is no longer in full control of fuel and timing . In the upper boost and rpm range , the SS box pulls a bunch of timing and adds a bunch of fuel . So when you let off the gas , the ECU starts to lean it out some and you feel a gain in power .
COlin
03-05-2006, 08:29 PM
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Originally Posted by booger
It maybe a belt slipping up top....hard to say from here
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