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Discussion Starter · #1 ·
2001 6# lower 60# injectors 255lph pumps tuned 2yrs ago about 10k miles since tune.

truck had been 14.7 +/- AFR during normal driving and 11.5 +/-.2 AFR WOT for 2+ years. now its 10-10.1 AFR at full throttle and still 14.7 during normal driving. truck runs great except WOT power seems a little down and wideband shows rich. idle is perfect.

fuel pressure rises correctly on gage during boost
intercooler pump is running
replaced plugs
no CEL
cleaned mass air sensor (had no effect)

any ideas what to check next?
 

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Panty Dropper
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If you can data log check the o2 sensors. A lazy o2 sensor can do that, and from what I've read a completely dead sensor will allow the computer to use only one side and assume the other side is the same.
 

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If you can data log check the o2 sensors. A lazy o2 sensor can do that, and from what I've read a completely dead sensor will allow the computer to use only one side and assume the other side is the same.
The O2 sensors aren't used at WOT (open loop) - only in closed loop.

The main factor in WOT fueling is the MAF - it tells the PCM what the air flow is and the PCM adjusts the fueling accordingly - could be the MAF is reading wrong at WOT or possibly the FPR is regulating the fuel pressure go too high now.

OP - what MAF are you running ?

Bird
 

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Discussion Starter · #4 ·
MAF

first off thanks for trying to help me with this.

its an SCT2600
the fuel pressure seems to be rising lb for lb with the boost

can I check the o2 sensors with an SCT X3?

they are the originals with 70k on them so maybe it would by a good PM to change them.
 

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Panty Dropper
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The O2 sensors aren't used at WOT (open loop) - only in closed loop.

The main factor in WOT fueling is the MAF - it tells the PCM what the air flow is and the PCM adjusts the fueling accordingly - could be the MAF is reading wrong at WOT or possibly the FPR is regulating the fuel pressure go too high now.

OP - what MAF are you running ?

Bird
Good point, forgot about that. Have you recently cleaned/changed your air filter?
 

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Discussion Starter · #6 ·
air filter

air filter was last cleaned in the spring. no extra oil on anything. I learned that on the fox mustangs
 

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Discussion Starter · #7 ·
fuel pressure

the fuel pressure rises from 36 to 54 psi under full boost (15 psi).
would the fuel pressure rising 3 psi more than boost be my problem?
 

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Panty Dropper
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Is 36 in vacuum or at "0". Boost rises 1:1 with fuel pressure, but vacuum is a little different. Should be ~40 with the boost gauge at 0 (can check with vacuum removed from regulator as well), which would be about 14 psi.
 

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Divergent
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If any hose that sees vac & boost has slipped off, a boost leak will cause it to run rich, its dumping fuel but not getting the air

Have you plugged the hole on the rear of the turkey pan?
 

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I have the exact same issue. I was suspecting turkey pan hose, but it passed a smoke test and i just pulled the blower so im hesitant to go back there so soon...

Please post back if you figure it out OP!
 

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Dude
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Is the weather getting colder where you guys are at? A dirty Maf could do it.
Just spit ballin here:smt102
 

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Its not a cold weather thing for me, but i could look into cleaning my MAF, that could be an issue since i havent looked at it in 20k miles.
 

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The main factor in WOT fueling is the MAF - it tells the PCM what the air flow is and the PCM adjusts the fueling accordingly -
Are the LTFTs added to the commanded AFR at WOT?

So say he had a vac leak and his trims were high, does it add that percentage of fuel to WOT AFR?
 
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