Possible bad maf

[ricqik]

Hi guys, just been watching and browsing but now have a question.

Was driving the 92 ls400 and for some time and noticed some slight lost in power one day. After getting home that night I noticed a slight red glow under behind the passenger wheel as I walk away. My curiousity got me on the ground peeking under the car, found my cat was red hot. I let it cool overnite and the next morning I went to start the car and she started fine. But upon putting it in gear to go she sputters with the rpms climbing very slowly. She idles fine in park and in drive, atleast it feels like, and sputters when I get on the gas, it didn't matter if I lightly press the pedal or floored it. Exhaust smells real rich. I'm thinking maf but am unsure I want to shell $1k for a new one if it ain't.

 

[Zuffen]

Disconnect the wiring at the MAF (AFM) and see if the car runs better or worse. It shouldn't run better but if it's worse it would suggest MAF/AFM isn't the culprit.

Before buying a new one try to borrow a spare and test it. $1k is alot to spend on diagnosis if the MAF/AFM isn't faulty.

 

[Toysrme]

Toyota MAF's are not common to failure.
Normally they just get a film on them that insulates them fmro the tmeperature changes & changes the resistance. Carefully clean them with some rubbing alcohol on a q-tipe.


I always put bad spark before bad fuel on imports & especially EFI Toyota hardware. Once you get past the nit-picky things like a dirty MAF wire, the failure rate for fuel components is simply higher than spark related components.



Clean the MAF, reset the ECU & see what happens after that. If it's still sputtering start pulling spark plug wires & see what cylinder it's on. Just don't go driving like that, if the cat isn't toast yet, it soon will be!

 

[ricqik]

I check all the plugs and plug wires and they all zapped pretty good. I'll try cleaning the maf next then. If that doesn't work I 'll ask my sister to come over and I'll swap her maf in to test if that's really the culprit before I decide further what to do.

 

[Lextek]

You could have a coil that is failing. Red hot cats mean very over rich condition.
If both cats are getting red, check for a coil. If one cat only is getting hot, check for a cylinder misfire.

 

[Nick M]

Do not clean that AFM. For starters, it is not a MAF. MAF=mass air flow. It is a volume air flow meter. It is called a Karman Vortex meter. There is a reflector and small LED inside. Do not spray anything in it ever. This usually ruins them. Ask all the kids with a first gen Supra(87-92) about their AFM after cleaning it. Or installing a K&N and having it to wet.

edit: as said above, the glowing cat is overheated. It is probably rich/clogged with carbon deposit. Fix it before your car burns to the ground. If you dont think that happens, think again. Sorry to be blunt, but I have seen Toyotas burn to the ground from the cat being full of unburnt fuel, and when finally heated up properly, it burned.

 

[SCV8]

Yep, he speaks the truth.
Your workin' on a chimney fiarrr.

 

[ImpNewbie]

I just took my car to the shop with a rough idle similar to bad plug wire/plug. The shop changed my wires and plugs and cleaned the fuel injectors but told me that the Mass Air Flow regulator needed to be changed. $1k from the dealership, $400 from an import parts place locally...if they can find one. Check engine light and codes, per my mechanic, says it's bad. Are there any online parts dealers to order these from? The car's still chugging badly and can barely pull a hill. With the comments posted above, I just wanted to make sure that I'm taking the right steps to eliminate the problem.

 

[SCV8]

Before any large sums get spent, take a good close look at the rubber hose that connects the Mass Airflow Meter to the engine; it is also attached to the aircleaner. This part can crack, cause an out of range error code for the airflow meter.
Good luck.

 

[Nick M]

If you dont physically act on that kind of air flow meter, they usually dont go bad. There isnt anything to "burn up". Like he said look at those connections first. If you arent sure, find somebody else that is. Those things are expensive.

 

[ImpNewbie]

I was fortunate enough to find a used one for about $135 shipping and all. It bolted right up and I was back on the road. It was a reasonable alternative to the $1k Dealer cost for a new one and even around $400 for a rebuilt one.

 

[Nick M]

Good to hear.