I have a 89 gxl that will not idle. I got the injectors refurbished and gave her a full tune up. This thing refused to idle no matter what I tried until I noticed the maf harness had a different plug on it. A few of the wires off the plug were a different color from the harness. I started it without the maf hooked up and it idled next to perfect at 750. When I hooked it back up she ***** the bed? Do I have a wrong maf or wired wrong. please someone enlighten me. I want this thing to run under 2000 rpm by itself so bad.

 

Get a multimeter and check everything at the ECU. That should be the #1 starting spot for just about everything. After that, if it's not solved by what you find it's more than likely a vacuum leak like 99% of all other idle problems.

 

Can you post a photo of the unit? What number is printed on it? n326, n371 etc...

 

I looked at it and it says n350. They is three brown wires and two blues coming off the plug and the harness has three brown a black and a green. The browns match in color but that's it.

 

And there looks like a ground strap of some sort that someone hooked to the neg on the batt

 

Five wires. A Green/Orange.............a Brown/Black..........another Brown/Black.............a Brown/White..........and last a Green/Orange

Both brown black are ground wires. The brown/white is 5vdc ref voltae...........a green wire is the output from the sensor to the ECU...........and that other wire is the air temp sensor signal to the ECU. Your plug and wires should look like the attached jpg and the output of that sensor should be what is given the first jpg attached.

 

Is there any known remady or reason for a ground going to the batt coming from the maf harness? It kind of makes me nervus to have something connected to the ecu that risk shorting out. The wire connects to what looks like a really thin ground strap inside the harness. I noticed the O2 sensor harness also had this thin ground strap. Does anyone no what this is?

 

Sounds like it's just shielding, probably nothing to worry about. If the AFM checks out fine at the ECU I'd be willing to wager it's vacuum related. A quick and dirty way to check that out is by starting the car and holding the AFM cone open by hand, you should be able to manipulate the AFM in such a way that the car will probably idle pretty close to normal.

 

02, AFM and boost sensor output all are in a shielded harness. The shield is to prevent EMI from interferring with the output signals.

I've no idea what your meant by "a ground going to the batt coming from the maf harness?".

You really NEED to check the output voltage AT the ECU that is coming FROM the AFM, like I FRY RICE said in post #2.

 

Lol that's what I thought it was but I had to make sure. The guy I bought this from was probabley trying anything lol.

 

Anyone know why the colors don't match? It has a N350 AFM. Was there any other S5 AMF. I can't get the motor to come close to idling with it hooked up.

 

Don't worry about the colors. Worry about checking the values at the ECU and looking for vacuum leaks (which is probably why the car won't idle). We can't do much for helping you if you don't do anything we suggest.

 

So I just looked at my wires and what I have is green wire -orange brown-black brown-black brown-white and a solid black with the mesh around it.

 

 

alright i figgured out the wires forget i even said anything about colors.

 

So I reconnected the afm and she won't start but unhooked it runs next to perfect. What else besides afm would cause this?

 

It's POSSIBLE the brown/white wire (ref voltage) is corrut inside the AFM and that is effecting all the other ref voltage inputs to other sensors and that is why the engine won't start with the plug on the AFM.

It's easy to find out if that is true or not. Just key to ON and backprobe the ECU at pin 2I and compare your reading with what's given in the FSM. Should read 4.5 to 5vdc. If it reads say 2vdc........then unconnect the afm plug and see if it rises to 4.5 to 5vdc, confirming the afm is killing the ref voltage.

And while your there, read the volage on 2B and compare it with the FSM reading given in my earlier post/jpgs.

I learned something from this thread. On a series four car, if the afm plug is pulled off (and the wiring is stock and not fooled with) the car will die because the fuel pump will stop running., But evidently on a series five it matters not if the afm plug is pulled off. How 'bout them apples.