code 31 afm

[suprra_girl]

hey ya'll... need a bit of help with mums car

it's thrown code 31 and has for quite some time, i have tried 2 other diff afms and i still get code 31 and i don't think the other afms are faulty, is there a common wiring fault with the harness? Could it be actually something else.

I did the voltage checks at the ecu and all are within spec

When the car is cold if you accelerate a little and drop the throttle she'll hunt like a mofo and try to stall but only when cold and doesn't do it all the time.

She's also running pig rich, i'm assuming this is to do with her fp being 12v and possibly a small boost leak (a pinhole somewhere)

anyway... any help appreciated

 

[Supra87T]

have you checked all your afm's using the tsrm? sometimes if they sit around they go bad. i had 2 of them bad in a row before i bought the maft pro.

 

[DLSupra]

ive also heard they go faulty after sitting around. I hope mine isnt faulty( car is out of comission )

 

[csolstad]

could be bad wiring

 

[jetjock]

Why would they go bad sitting around? Elves?

 

[bountykilla0118]

dwarfs

 

[jetjock]

Gotta be mighty small ones to get into that little hole .

I can't envision what mechanism might be the cause of them failing as long as they're stored in a clean dry place. My spare has been sitting around for 20 years and the last time I checked (a year ago) it was as good as new.

 

[suprra_girl]

anyone got a link to the tsrm page for checking the actual airflow meter? and the afm wiring section?

 

[Supra87T]

they go bad from moisture, dust and other crap. i'm not trying to say everyone of them goes bad, but i know i've had two bad ones. i bought one from a member off ebay guaranteed working and it didn't read within spec and the one that came with my jdm engine didn't work either.

edit: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&Page=96

 

[suprra_girl]

hmmm i remember that test, yea i did that one and the one on her car was all good... is that the only thing you can check?

 

[jetjock]

This is a turbo car? Plug the thing in and measure the voltage between KS and ground with the key on engine off. It'll be pin 3, a light green wire with a red stripe. Then do it with the engine running. Also measure between VC and ground. That'll be pin 4, light blue wire with a red stripe. Report back and we'll go from there.

 

[suprra_girl]

altho your post didn't help with what you were intending... it did find my problem LOL

colours are different also and yes turbo

turns out when i turn the plug over i found two bared wires which touch each other and bam that's our prob

thanks

 

[jetjock]

It's always the simple stuff eh? It had to be the wiring since all your AFMs did the same thing. That's where I was going with it. Had the voltages been wrong the wiring would have been suspect. See, the diagnostic system in this computer isn't very smart. Generally speaking it sets a code only when one of two voltages are present on a sensor line. Those two voltages happen only if the sensor wire is broken or shorted but without measuring you can't tell which. Had you not seen it you would've ended up measuring the shorted voltage level and then known to look for bad wiring touching something else.

Colors came from my book but pin numbers should be the same. If I were you I'd measure them anyway. That way you'll know what's supposed to be there