LTFT are backwards
Thread Starter
Teching In
Joined: Oct 2003
Posts: 45
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From: Columbia,SC
LTFT are backwards I just got done testing my car out and i notice that my LTFT are maxed out at 25. So I went into the MAF Vs Fec. Table on HPtuners and made some adjustments and got the LTFT's between -.08 and 0 at WOT. But I still have one problem at idel my LTFT's are still maxed out at +25. But as soon i give it gas it jumps down around -.08 and 0. PLease give me some advice about what the hell it going on with my POS. Everyone is saying that the LTFT should be in the NEG. at idel and when you get in the gas it should go up around 0. Thanks.
......... Only time ive seen that is bad 02's
Originally Posted by LS1firebird95
I just got done testing my car out and i notice that my LTFT are maxed out at 25. So I went into the MAF Vs Fec. Table on HPtuners and made some adjustments and got the LTFT's between -.08 and 0 at WOT. But I still have one problem at idel my LTFT's are still maxed out at +25. But as soon i give it gas it jumps down around -.08 and 0. PLease give me some advice about what the hell it going on with my POS. Everyone is saying that the LTFT should be in the NEG. at idel and when you get in the gas it should go up around 0. Thanks.
Vacuum leak can mess up idle trims with less
effect at higher RPM/MAP.
Sleepy O2s are a common result of headers and
will make for false trimming.
The MAF has a pretty small contribution to low
RPM airflow metering and fuel trims. If the MAF
is stock then put the table back to stock. If
the MAF is not stock, that's another story.
Add some description of the car & mods to your
.sig so people will do less guessing.
effect at higher RPM/MAP.
Sleepy O2s are a common result of headers and
will make for false trimming.
The MAF has a pretty small contribution to low
RPM airflow metering and fuel trims. If the MAF
is stock then put the table back to stock. If
the MAF is not stock, that's another story.
Add some description of the car & mods to your
.sig so people will do less guessing.
I agree with "Vacuum leak". Mine did the same thing this week and I found a crack in my intake at the back. The first sign was really high idle until I got below 10 MPH. Then I hooked up EFI and found the LIFTS at 25% (their max).
Ported MAF must go. That's pretty much a wild guess
for tuning. If you can borrow a stock MAF for a bit
then you could dial in the car, and then deal with just
the ported MAF recalibration. With all the ported ported
ported you have some work to do on the speed density
side and the headers are liable to have messed up the
O2s at low gas flows. Look at the real time O2 sensor
activity at idle and light cruise, see if they are properly
jiggy or just barely stumbling out of bed.
for tuning. If you can borrow a stock MAF for a bit
then you could dial in the car, and then deal with just
the ported MAF recalibration. With all the ported ported
ported you have some work to do on the speed density
side and the headers are liable to have messed up the
O2s at low gas flows. Look at the real time O2 sensor
activity at idle and light cruise, see if they are properly
jiggy or just barely stumbling out of bed.
I believe your VE table is too low in the idle and surrounding cells. Like jimmy said, the maf contributes minimally to low airflow situations. I'd double check your SD tune. Then, return the 3000Hz and lower frequencies back to stock and tweak the MAF from there.
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