I just had my ECM out today and noticed I was completely missing the MAS. I still have the original 870 ECM so I know I am supposed to have this thing. I looked every where under the dash (thinking it might have broke off) but it is not there. Period.

What will the car do without this module?

Here is a pic of the ECM.

 

I did find this module mounted here though. What is this?

 

And this was the only plug under there not connected to anything.

Is this the MAS plug?

 

Not only are you missing the module, you're also missing the bracket for it as well. It has a six pin connector for it and the wires for it are coded as follows.
Pin "A" = orange
Pin "B" = pink/black
Pin "C" = orange
Pin "D" = dark blue
Pin "E" = black/white
Pin "F" = red

Hope this helps!!!

EDIT: whoops! had a typo in the book and had to look up the schematic to get the right color codes.

 

Thanks, I guess I will have get under there tommorow a look around for those wires.

This may be my problem. But why is the car not losing any performance?

 

Are you getting a code 33 or 34?

 

Nope, no codes at all

 

Well, just on a hunch and for sh*ts and giggles. Look under the hood on the drivers side firewall and see if there might be a MAF burn-off relay mounted there.

 

Nope, nothing that even looks like a MAS.

I like pics

 

This could be total BS, but one of the first TPI setups I ever bought did not have one (from an '85 'TA). When I pushed the seller on it, he claimed he couldn't find one. There was no bracket for this one either. Fine, not knowing they are a (nearly) $1K piece, I went to the dealership to try to order one. It was there they informed me that supposedly not all of the '85's came with the burnoff module. I dunno what else they would come with though. They topped this off by ordering the wrong part.

 

So what does this burn off module do anyway? And if they were put on some why not put it on all of them?

 

The way I understand it is that after driving your vehicle, the thin wire inside the MAF heats to a very high temperature, essentially burning off any debris that accumulates. The burnoff module as seen in '85 contained a "mini" ECM AND a relay for conducting just that activity. Starting the following year, '165 ECM's contained the programming to do what the module was doing for the previous generation ECM. They just added a relay exterior to the ECM. I'm not sure that this explanation is entirely correct, but this should be the jist of it (I hope).

 

So how is my MAF cleaning itself?

 

They only came on the 5.0L TPI engines. Check this trouble shooting chart for the MAF.

 

page 2

 

Follow this plug. I may be wrong since it has been a while since I have had my ECM out but that looks like the plug to the module. Mine is mounted to the dash not the ECM (or else someone has wedged it in there really tight before I got the car).

 

Ok, I looked at a closer pic of that plug and it looks like it goes along with the right color of wires. So I will look at it tommow.

Thanks

 

Some pics to, hopefully, help:





From this site which should be some good reading for you.

I didn't think that the MAS was connected to the ecu directly though. That's what those wires in the pic look like. Maybe someone already did the conversion?

 

Well I found it. It was mounted way up into the dash, I could not even find how to unmount it. I guess you have to pull the dash pad off.

Thanks everyone for helping me find my MAS

But I have one last question:
Why are some of the MAS's mounted on the ECM and some mounted way into the dash? Was it different assembly plants?

 

Must have been the crack.

 

not crack, just gm itis (we all love it though)