MAFT Question
Thread Starter
Teching In
Joined: Nov 2001
Posts: 43
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From: Raleigh, NC
MAFT Question I have a few questions concerning MAFTS. First, once you have dialed in your LTrims shouldn't they stay close to 0 even if outside conditions change? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> It seems that a big shift in the weather will take my numbers off and in two cases has made the car run so rich that it wil not stay running at idle. I would think that the PCM should be able to account for those shifts in temp and humidity just like if it was stock. Is it my translator? Second, I have to get my car inspected this month and I wanted to set the the car up to run lean so I will have a better chance of passing. So I just want to clarify what the numbers should look like. If I have induced a lean condition the LTrims should be negative right? This means that the MAFT will be tricking the computer so that it will be taking fuel away from the same amount of air comming into the car. Any help / suggestions would be greatly appreciated.
Matt
Matt
Re: MAFT Question The car will learn out a lean setting, except possibly at idle.
The LTRIMs should not swing hugely with temp; there is a temp correction factor in the pcm, but it may not be exact.
The LTRIMs should not swing hugely with temp; there is a temp correction factor in the pcm, but it may not be exact.
Thread Starter
Teching In
Joined: Nov 2001
Posts: 43
Likes: 0
From: Raleigh, NC
Re: MAFT Question It will learn it out but it will take a while so if the adjustment is done right before the test than it should have an effect. As far as the temp shifts I am at a loss. Does anyone know how to test a MAFT?
Re: MAFT Question Operator error? or something is wrong with your car. Just let me have it I'll test it out for you.
<img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" /> <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
<img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" /> <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />
Re: MAFT Question Please correct me if I am wrong....If your avg LTFT's are negative, you are on the "rich" side during cruise.
Please let me know,
Randy Hughes <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Please let me know,
Randy Hughes <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
TECH Addict
Joined: Nov 2001
Posts: 2,207
Likes: 0
From: College Station, Tx
Re: MAFT Question It means the computer is pulling out fuel because your calculations call for more fuel than the computer finds it needs with the O2 feedback.
You will be at the same ratio at part throttle by virtue of the O2's - the LTFT just indicate how far off your calculated fueling values are.
Chris
You will be at the same ratio at part throttle by virtue of the O2's - the LTFT just indicate how far off your calculated fueling values are.
Chris
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Re: MAFT Question So.....the result is the computer is attempting to lessen (take away) the amount of fuel anticipated (calculated) by the computer that will be needed for a given MAF rate. Which if the LTFT are a negative avg (cells 1-19) that means the computer is subtracting(by means of a guessed nega. calculated %) fuel available. Which leaves more fuel "available" during a WOT request and no anticipated fuel adjustment needed (LTFT's should ideally equal zero). This would arrive you at the best chance of using all fuel available, therefore creating the best "rich" condition available.
The opposite case of a avg. positive number would create a situtation for the computer to adjust for the excess requested and allocated fuel during cruise and not guessing correctly causing less fuel available during WOT, "leaner". That is why small LTFT's is better because the computer has less room for error.
BTW, these are my discoveries and "assumptions" based on about 2 weeks of "going to school" on this subject. This forum has been wonderful source of info. from a seamingly great bunch of guys ( and girls). I appreciate your comments and insight!
OBTW, I am including new avitar to show I got it looking not as scarey. Wasn't that difficult.. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
Good Hunting! Heeere Snakey, Snakey..... <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" /> <img src="http://www.camaro-ss.com/gallery/reader214.jpg" alt="" />
The opposite case of a avg. positive number would create a situtation for the computer to adjust for the excess requested and allocated fuel during cruise and not guessing correctly causing less fuel available during WOT, "leaner". That is why small LTFT's is better because the computer has less room for error.
BTW, these are my discoveries and "assumptions" based on about 2 weeks of "going to school" on this subject. This forum has been wonderful source of info. from a seamingly great bunch of guys ( and girls). I appreciate your comments and insight!
OBTW, I am including new avitar to show I got it looking not as scarey. Wasn't that difficult.. <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
Good Hunting! Heeere Snakey, Snakey..... <img border="0" alt="[devil]" title="" src="graemlins/gr_devil.gif" /> <img src="http://www.camaro-ss.com/gallery/reader214.jpg" alt="" />
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