dsmer

hey guys im new to this site im trying to find some help, i've look and done my homework searching about the problem but so far no luck,

PROBLEM

98 lexus gs400
100,000 miles

no spark in 3,5,7,2
coils are fine i switch them around and they do fire

2 CODES
P0100 MAF mass air flow or VAF volume air flow sensor circuit
P0110 IAT intake air temperature sensor circuit malfunction

i bought a brand new oem maf sensor and spark plugs, but nothing still misfires bad and dies wont stay on i check the wiring harness and is in good conditions, i took out the ECU and nothing seems burn, capacitors not leaking, seems in good conditions all fuses are ok could it be timing belt that might jump a tooth? i dont thin so since theres no spark in half of the coils. anything will help

thanks

lextout

timing belt isn't the issue, i think its something minor. Hope you get it solved soon, with those miles on your gs you got 50k more miles before its even broken in.

GS4_Fiend

iTrader: (22)

Check if there is power to the coils. There also should be a Pulsing on/off on the ground side meaning the pcm is firing the coil. The third wire would be the signal wire. There should be voltage when car is on.

tinman

Yup. Time to break out the multi-meter. Too bad you're in CA, this is just the kinda project I like to bang my head against until I fix it. I'm strange like that.

dsmer

thanks guys, im gonna look into the wiring harness to c if theres signal going to the coils

dsmer

hey guys im back it tokk me a little longer to check the car due to back injury, finally i was able to check the car every coil is doing its job firing, what notice is when i have the maf sensor plug in the car misfires bad but when i disconnect it its more stable runs better seems like that could really be the problem but i bought a new maf sensor im thinking that maybe i have to reprogram the computer do any one knows if i have to do that ,

kdick91

Well, if that is the case, just unplug your battery for at least 15 mins or so. That allows the PCM to relearn. If you're still having issues, I'd check your pigtail going to your MAF. See if one of the pins is bent/missing. Do you have a paper air filter? If you're using an oiled air filter (K&N) you may have over-oiled it and fouled the MAF with oil. My last possible suggestion is that you had a bad MAF and the new one you got, is also bad. It's a slim, slim chance so I wouldn't bank on it.... But it happens! Good luck getting it fixed!!

jcat_350

Definitely a MAF issue. If it's running better when disconnected, it should be showing a CEL and will then rely on the o2s in the exhaust to run.

dsmer

it has the stock air filter and i already disconnect the battery and check the plug but still doing the same thing i really think that might be the maf sensor even the new one that i got i think that one doesnt work either is suppose to be new from autozone but i know autozone is garbage i got the new one not a rebuild one ill look into it thanks

jcat_350

I'd never buy critical engine parts from autozone. some detailing supplies, oil/filter, brake pads, sure. But nothing critical.

tom steele

i am sorry but have you tried injector cleaner if you injectors get clogged acts the same as coils being out try some seafoam or lucas fuel treatment i had mine sitting for awhile and i thought my coils were bad ended up just being the injector need a little love

tom steele

also if the new maf is acting the same as the old maf take it back dont tell them you installed it though just get some maf cleaner and clean your stock denso unit up its much better then auto zone units.

diagtime

those mass air flows almost never have problems. you said oem mass air flow...i hope you mean factory.

but the circuit codes are suspicious. I'd make sure you don't have a wiring problem to the mass air flow. maybe a ground issue? lots of possibilities

dsmer

thanks guys but definetly im thinking it could b in the wiring because of the codes still giving me the same maf sensor n when i disconnect it i runs better