PCM learning at WOT?
Thread Starter
TECH Fanatic
Joined: Aug 2003
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From: Tranås, Sweden
PCM learning at WOT? Does the PCM "learn" at WOT... Example if the engine needs more fuel at wot does the PCM remember that until the next WOT? I know it learns at part-throttle...
Nope...our PCMs run in open loop at WOT simply due to the fact that the feedback loop is based off of narrow band O2 sensors. If your trims are positive upon entering WOT, then your car will dump in more fuel than it normally would to stay safe (that's why everyone says to shoot for slightly negative trims since they'll go to 0 @ WOT). The most your car can do is pull timing via KR at WOT.
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Joined: Nov 2001
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From: Lake Zurich, IL
at WOT the computer really has no way of knowing if it needs more fuel... it's based on the MAF and VE tables... and the PE table
If it detects knock it will lower total timing advance
If it detects knock it will lower total timing advance
Originally Posted by horist
at WOT the computer really has no way of knowing if it needs more fuel... it's based on the MAF and VE tables... and the PE table
If it detects knock it will lower total timing advance
If it detects knock it will lower total timing advance
Damn moderators...
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Joined: Mar 2003
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From: San Diego
Nope. The only way your 'VE' learns is if you teach it.. 
Its the same table, but doesn't use any of the fuel trim corrections.
You VE table is fixed in your flash, as is your MAF table. If you tune your VE table by using the correction factors (fuel trims) then your VE table could be considered 'learned'.
When in closed loop (i.e. driving around) it learns via fuel trims. The fuel trims give it a correction factor which it uses when in closed loop but upon entering open loop it no longer uses those correction factors (except in the case previously mentioned), and depending on how you have your PCM setup it either takes fueling straight from either your VE table only (Speed Density) or VE/MAF if you are running mass air.
Its the same table, but doesn't use any of the fuel trim corrections.You VE table is fixed in your flash, as is your MAF table. If you tune your VE table by using the correction factors (fuel trims) then your VE table could be considered 'learned'.
When in closed loop (i.e. driving around) it learns via fuel trims. The fuel trims give it a correction factor which it uses when in closed loop but upon entering open loop it no longer uses those correction factors (except in the case previously mentioned), and depending on how you have your PCM setup it either takes fueling straight from either your VE table only (Speed Density) or VE/MAF if you are running mass air.
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You may see fuel trims applied at WOT but these
are learned in closed loop and applied "just in case",
if the PCM thinks there's lean error. Not because
of anything to do with WOT operation. This is why
you want LTFTs <= 0%.
Persistent knock retard will cause spark learning
(Knock Learn Factor" away from high octane, and
toward the low octane table value.
are learned in closed loop and applied "just in case",
if the PCM thinks there's lean error. Not because
of anything to do with WOT operation. This is why
you want LTFTs <= 0%.
Persistent knock retard will cause spark learning
(Knock Learn Factor" away from high octane, and
toward the low octane table value.
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Thread Starter
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Joined: Aug 2003
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From: Tranås, Sweden
Originally Posted by Bombguy99z28
Nope. The only way your 'VE' learns is if you teach it.. Its the same table, but doesn't use any of the fuel trim corrections.
You VE table is fixed in your flash, as is your MAF table. If you tune your VE table by using the correction factors (fuel trims) then your VE table could be considered 'learned'.
Its the same table, but doesn't use any of the fuel trim corrections.You VE table is fixed in your flash, as is your MAF table. If you tune your VE table by using the correction factors (fuel trims) then your VE table could be considered 'learned'.
Originally Posted by Bombguy99z28
When in closed loop (i.e. driving around) it learns via fuel trims. The fuel trims give it a correction factor which it uses when in closed loop but upon entering open loop it no longer uses those correction factors (except in the case previously mentioned), and depending on how you have your PCM setup it either takes fueling straight from either your VE table only (Speed Density) or VE/MAF if you are running mass air.
If i tune in my VE-table correct (i am i SD and are tuning with hptuners) then the engine should have the correct (ok i know i have to have a WB to tune it in perfekt) air/fuel at wot... I don´t want my engine to go lean and knock... or am i wrong again
Thanks for all the help, I really mean it
Thread Starter
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Joined: Aug 2003
Posts: 1,130
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From: Tranås, Sweden
Originally Posted by MeentSS02
Yes...if your VE table is dialed in (as verified by a Wideband), then it will do what you ask it at WOT through the PE table.
Merry Christmas from Sweden
Ok so I got most of my VE table to 14.7AFR. But how do I command a diff AFR for PE. I want my PE to kick in at 75Kpa. What would I put in the PE table to command 12.5 and 12.8? THanks.
See my post in your other thread. I think I may have explained myself well enough. If you are still having trouble, send me a PM, I'll get your phone number, and I'll talk you through it myself.
Thread Starter
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Joined: Aug 2003
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From: Tranås, Sweden
Originally Posted by MeentSS02