Hey guys, need help with lean mixture
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From: Bensalem, Pa, now montreal, Quebec
Hey guys, need help with lean mixture My car started running really lean and i cant figure out why, ive posted in here before, but ive checked for leaks or whatnot. Im getting 10mpg and KR,i did some efi live and sometimes the kr is down low and its up high around 4k or so. ltfts are positve 5 to 8 and at WOT positive 5 usually. So the car is compensating, would 91 octane do this? im used to sunoco 93 ultra but up here all they have is 91 and 94, but the 94 has an injector clogging additive they put in the gas so your fuel lines dont freeze during the winter. How can i rule out shitty gas? then whats the next step.
Ah...I see you have a Holley filter, probably the oiled cotton/gauze type, right?
Sounds like your MAF is under-reporting air volume being delivered. Hence the very positive LTFTs.
Typical failure mode in this scenario is the filter oil gunked up the MAF thermistors. Hit your local Radio Shack, get a can of Electronics Parts Cleaner, and remove your MAF. Spray the thermistors and filaments, allow the residue to run off, don't physically touch them. Allow it to dry, then reinstall and reset your PCM to clear the LTFT data. Take a spin and report back.
Sounds like your MAF is under-reporting air volume being delivered. Hence the very positive LTFTs.
Typical failure mode in this scenario is the filter oil gunked up the MAF thermistors. Hit your local Radio Shack, get a can of Electronics Parts Cleaner, and remove your MAF. Spray the thermistors and filaments, allow the residue to run off, don't physically touch them. Allow it to dry, then reinstall and reset your PCM to clear the LTFT data. Take a spin and report back.
Thread Starter
TECH Fanatic
iTrader: (3)
Joined: Mar 2003
Posts: 1,162
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From: Bensalem, Pa, now montreal, Quebec
yeah i have the holly. however my car was fine for a year with it on, and i never reoiled it, so i dont get how oil coulda got on it considering i didnt reoil it!
There was oil on it from the factory, and the MAF problem doesn't usually happen immediately. I'd clean the MAF just as a starting point and go from there.
While you're removing it, pay close attention to the ducting for tears or signs of leakage. Check the vacuum lines elsewhere on the engine, especially the ones on the back of the intake that feed the brake booster and HVAC controls, for signs of damage or leakage.
The symptoms point to unmeasured air getting into the engine somewhere.
While you're removing it, pay close attention to the ducting for tears or signs of leakage. Check the vacuum lines elsewhere on the engine, especially the ones on the back of the intake that feed the brake booster and HVAC controls, for signs of damage or leakage.
The symptoms point to unmeasured air getting into the engine somewhere.
Might check your EGR tube where it goes into the intake too. That little o-ring is easy to pinch when you install the tube & if it's sucking any air it will cause that problem too. Like the other post said, air is getting in somewhere after the MAF.....
