car won't start, error code 12 (MAFS)

[sxevegan]

I was at an autoX today and I was all lined up on grid before my first run and I shut my car off. When i went to turn it back on it would start for about two seconds and then die. If I held the gas down all the way it would run like crap and it wouldn't go over 2000 rpms. It sounded like it was misfiring or something.

I hooked my logger up and it had an error code 12...mass airflow sensor. I reset the ECU and tried it again and after the 2 seconds of running it died again and i got another 12. I unhooked the wire harness from the MAF and plugged it back in but I had no luck there. It still wouldn't work.

I just changed the spark plugs two days ago so I pulled them back out to see if they looked ok. They looked fine...black but fine. I think ill try to put my old plugs back in just to see if one was bad. I also tried pulling each spark plug wire off and trying to start it to see if it would run any different and it was actually no different at all

Do MAFS just go bad in 5 minutes like that? Is there something else that can happen to the car to make it throw that code? Thanks in advance.

 

[boostedgst2984]

do u still have the stock MAS on there. And if u do The car should still run with out the mas. I had mine unpluged and it ran just not good. It could be the mas but im not 100% sure thats it though. Could be a coil problem. Check to see if ur getting spark to all the cyl.

 

[sxevegan]

i still have the stock 1g MAS. Thats good info for me to know about the car running with the maf unplugged.. Tomorrow when I have light again ill check the spark. Thanks.

 

[TotalEclipse112]

What it sounds like is the MAF is bad just not all the way bad. You said the plugs were new but blasc when you pulled them out. I think the MAF is still reading just not correctly. This happened to one of are cars at school the car wouldn't start and the scan tool was giving a MAF sensor code. Even when the key was in On not Run the MAF was reading 332 grams per second wheich is what you would see at wide open throttle. Yours is probally doing the same the black on the plugs is most likely unburnt fuel. The fuel is probally coming from the ECU thinking it is at wide open when it is not. At start up it is probally so rich the car is just falling on its face. Try changin the MAF see what happens, heck if you need one I have it in my garage that I want to get rid of pick up the shipping and its yours.

 

[sxevegan]

I changed the MAF and it didn't help. I'll check for a spark tonight.

 

[sxevegan]

update: I checked for a spark from all 4 wires....there is one.

I put my old plugs back in so i know the plugs are all good.

I checked my logger again while i was staring it and noticed that when i crank the car the MAFS will read about 88hz and then a split second later it read 0hz and then the car will die about a second after that.

Tomorrow my plan is to go to the local pull-a-part salvage yard and grab a harness for the maf. I'll wire that up and see if its the harness. I also might try to borrow an ECU and see if mine is fried.


Does anyone know where the wires go from the harness? Do they all go directly to the ECU? Are there other harnesses they pass through first? I might try to completely rewire the MAF if i find out my harness and ECU are both good.

 

[TotalEclipse112]

The fact that it is reading then not reading sounds like an eletrical problem. The ECU should be fine or you would have no spark at all. If I was in your place I would get a good wiring diagram, and check for a bad ground, or a short in the signal wire. That is most likley where the problem is not nessiclary in the ECU. Just trying to save you a couple of bucks.

 

[sxevegan]

I just noticed that my SAFC isn't turning on. Im going to check out the wiring diagram for that and see if i can figure anything out.

edit: the green wire is not plugged into anything. I need to find out what that is and where it goes. To me it looks like it should go to the black wire but i better make sure before i try it

edit #2: i plugged the green wire back in and didn't have any luck. I must have unplugged it when i was tinkering around earlier. I'm leaning towards my ecu. Hopefully my friend will be over later to test his in my car.

 

[sxevegan]

i swapped ECUs and it still won't run.

I remember playing with my AFC when i was at the autox. I was trying to move it into the glove box so that it wouldn't fall off its mount and mess me up while i was driving. Im wondering if i broke a wire inside the cable and thats what is messing me up. I never fully unhooked the afc to test the car...i only unplugged it from the quick connector. Tomorrow ill either completely unhook it or plug someone elses into my quick connect plug

 

[Jimmy Jr.]

Did you change a setting on the afc? It sounds like you might have a problem with the afc wiring. Maybe a short.

 

[sxevegan]

i didn't change any settings...it just doesn't turn on anymore. Im thinking a short or broken wire also

 

[sxevegan]

its fixed! Just in case it happens to somebody else ill post what was wrong...it was so simple.

The wiring harness INSIDE the SAFC was unplugged. I took the AFC apart and sure enough the harness was floating around. I plugged it back in and everything is grand. Thanks to everyone for the help.

Rob