Conceptvip

Ok im a master tech. at Lexus and I was working on my personal 92 sc400 doing a tune up cap, rotor, plugs, wires. I finished and was driving home about 15 miles or so later the car has a large missfire and has a large hesitation. I arived home and pulled all the engine covers off to make sure I didnt damage a wire and that the coil wires were pluged in. All okey. Heres the strange part with the air-flow sensor unplugged the car runs great and with it plugged in, it has a hesitation and misfire. I cannot find any vacume lines unplugged and checked the air box for cracks exc... I have not looked to far into the problem seeing that it is late at night and have to be up at 5, but this is gunna leave me wondering all night what might the problem be lol. ne help would be nice.. thanks

LexusFTW

iTrader: (7)

could try cleaning the maf sensor with spray contact cleaner. i suppose its not throwing any codes right?

Conceptvip

Already tried that and didnt change any thing..

neurocity

iTrader: (17)

This might sound stupid, but what about cleaning the contacts on the MAF sensor....the "male/female" connectors?

Conceptvip

yeah did a pin fit on the MAF and swapped the top coil out with another one i had laying around. the side one is brand new. still running the same... I think im gunna have to pull the cam covers off and check the rotors just to make sure there okey and i didnt hurt them, ill do that tomarrow after work lol

O. L. T.

iTrader: (17)

For a master tech your 12 posts on your problems have been horribly entry level / shadetree....... but regardless, if your car is malfunctioning with the MAF plugged in, the MAF is likely the problem.

Don't over think it. You could have a bad contact on the MAF wire harness. Hard to say really. Apparently you just need a better master tech to look at it for you. Two heads are better than one.

Good luck.

Conceptvip

Ok but how would not touching the maf at all (did not remove air box or touch wiring) during the service all of a suddenly go bad? I have a spare maf in the tool box and ill try that tom when I get home, but it’s probably something that I did like hurt a CAS wire. I haven’t really looked much into the car, just looked into the basic things that I could see in the dark. And sorry if it’s a bad thing to get some other options off this site…

happypanda

try disconnecting the battery and let the ecu reset...give that a shot...goodluck

1sxyrxy

so wait your a master tech at lexus and your coming to us.... hmm well try hitting the maf and see what happense. im sure you know it will change something well im not sure about ours but its worth a try. just go over everything again tomorrow

VJ RC51

strange misfire and hesitation usually always lead to maf....

But once on my sc300.. i had a loose plug wire (looked like it was on), and the car would stall, no power, ran rough, etc

LocknRoll

dude if any other member on this board would have said that, you would have banned or flammed them.

oh but your a mod, you can do whatever you want.

VJ RC51

This is why i fix all my own problems and never take my car to a shop.. Just because its a shop, it doesn't mean the person knows more then you about the car. There isn't one thing i cant fix, diagnose, or repair on a 1JZGTE, had to learn it all the hard way cause after all.. who would i take i to if something went wrong???

Conceptvip

yeah i found the problem, turns out under the intake plenum there was mice nest and they chewed part of the harness, i honestly dont understand why unplugging the MAF took away that missfire. Well doing the spark plugs and all i must of disturbed the harness just enough to break a wire. The car runs great now. thanks all