Quad Drivers bad??

92 Grand Am SE with the 3.3 engine. I've had alot of problems with this car and now I'm starting to hate it bad. On my scanner it shows that it has 4 quad drivers and two are bad and two are good. I have replaced TPS, VSS, NSS, MAF,and just the ECM but still no good. The car has a bad idle issue until it goes into a closed loop then runs fine. I don't know what to do next??? Any suggestions??

Thier is no specific part that is the "quad driver".
It is just a 4 way switch, that if a certain expected voltage/signal isnt present, then it trips the DTC for quad driver(s).

What Exactly was the code(s) it's showing??

Idle is controled by the idle air control valve-IAC on the throttle body. It's probley carboned up in the TB port and not able to adjust idle properly-smoothly.

Also did you have to do a relearn for the ECM ?

I agree with IAC being the problem in this case. On cold start (open loop) engine needs more fuel and more air, IAC opens (count increases) to allow more air. When engine warms up less fuel is needed and thus less air, so IAC closes (count decreases). IAC threads are very sensitive to dirt. Sounds like your iac is unable to open up more than it needs because of the dirt on its treads or clogged passages. This you can try. remove smaller vacuum line the best one would be from fuel pressure regulator. The idea is to create smaller vacuum leak to compensate for lack of air that IAC can not allow in due to what ever the problem is. So with the vacuum line unplugged and plug it with your finger and open it up slowly more and more to see if the idle will improve.

quad drivers are inside of the pcm

Thier is no specific part that is the "quad driver".
It is just a 4 way switch, that if a certain expected voltage/signal isnt present, then it trips the DTC for quad driver(s).

What Exactly was the code(s) it's showing??

Idle is controled by the idle air control valve-IAC on the throttle body. It's probley carboned up in the TB port and not able to adjust idle properly-smoothly.

Also did you have to do a relearn for the ECM ?
No #s for codes. My scanner as you read it goes down the line until Quad Drivers. The first two reads bad the other two reads ok. I took out the IAC and sprayed it with carb cleaner but didn't make no difference. These are like $85 so I want to be sure this is it. Could the IAC still be bad??

As far as the ECM all I did was took the MEM CAL out of the old and placed it in the new. How do you have the ECM relearn??

I agree with IAC being the problem in this case. On cold start (open loop) engine needs more fuel and more air, IAC opens (count increases) to allow more air. When engine warms up less fuel is needed and thus less air, so IAC closes (count decreases). IAC threads are very sensitive to dirt. Sounds like your iac is unable to open up more than it needs because of the dirt on its treads or clogged passages. This you can try. remove smaller vacuum line the best one would be from fuel pressure regulator. The idea is to create smaller vacuum leak to compensate for lack of air that IAC can not allow in due to what ever the problem is. So with the vacuum line unplugged and plug it with your finger and open it up slowly more and more to see if the idle will improve.

quad drivers are inside of the pcm
I'll try this...

No #s for codes. My scanner as you read it goes down the line until Quad Drivers. The first two reads bad the other two reads ok. I took out the IAC and sprayed it with carb cleaner but didn't make no difference. These are like $85 so I want to be sure this is it. Could the IAC still be bad??

As far as the ECM all I did was took the MEM CAL out of the old and placed it in the new. How do you have the ECM relearn??

Not only do you need to clean the IAC, more importantly the TB side of it. I've seen these older ones with only a pin hole going thru the TB port for the IAC. And the TB in general probly needs a cleaning, wouldnt hurt anyway.

You can test the IAC and find out how its working. Pretty easy with a voltmeter or scan tool that can read the perameters. And yes the IAC's are pricey!

First unplug the IAC, on the plug are letters marked ABCD.
Using an ohm meter test terminals A & B on the IAC. Should have between 50-80ohms.
And then the same for terminals C & D on the IAC.
If both test out of range, the IAC needs replaced.

And btw here is a diagram of how a quad driver is set up, though this ones for a newr model.
http://www.troublecodes.net/articles/qdfig1.gif

And on the ECM you might have to have a scan tool to do a relearn if thats causing problems. :2cents:

Not only do you need to clean the IAC, more importantly the TB side of it. I've seen these older ones with only a pin hole going thru the TB port for the IAC. And the TB in general probly needs a cleaning, wouldnt hurt anyway.

You can test the IAC and find out how its working. Pretty easy with a voltmeter or scan tool that can read the perameters. And yes the IAC's are pricey!

First unplug the IAC, on the plug are letters marked ABCD.
Using an ohm meter test terminals A & B on the IAC. Should have between 50-80ohms.
And then the same for terminals C & D on the IAC.
If both test out of range, the IAC needs replaced.

And btw here is a diagram of how a quad driver is set up, though this ones for a newr model.
http://www.troublecodes.net/articles/qdfig1.gif

And on the ECM you might have to have a scan tool to do a relearn if thats causing problems. :2cents:
Hmmmm, that is interesting!! I think I'll swap back the old ECM until I find out exactly what the problem is. I will definately check the IAC per your instructions.
And by looking at your illistration it seems to me that a quad driver controls certain function within itself. So I'm thinking one little item could be bad and cuasing the driver to say it's bad. Right??

I checked the IAC and both A-B and C-D were 50 ohms. Cleaned the IAC and the TB very good. Started the car and died, started again and if you don't give it gas it will die. After a few minutes the idle will surge up and down until it is fully warm. I don't know where to go from here but I will tell you I'm very fustrated.

you said that you replaced memory pack from the top of the pcm, check it again this also sounds like the pcm is not holding memory. Example if you disconnect battery for a long time and when you reconnect it back engine will idle like you described until iac relearns itself.

so something is telling me that when you shut off engine and start it back again iac is always relearning.

Ok here's something, when I had the IAC out I was able to unscrew the pintle all the way out where now I had three pieces (motor, pintle rod, and spring) I screwed it back in but is that normal to be able to do that??

Yeah you're not supposed to turn the pintal...

It should be screwed in untill it is 1 1/8" from the tip of the pintal to the base of the IAC. Replace in TB and connect plugin.
After that turn the key "on", but don't start, for 10 secs then turn the key off for 10-15 secs. This should relearn the IAC.

IF that doesnt work I'd bet you have a bad vacum leak.

Also make sure your MAF sensor wires are not damaged by the sensor plug.

IAC should relearn itself after driving couple of miles,
the other way to relearn the IAC is to pull emergency brake, shift into D and let the engine idle until the cooling fan turns on.

The exact reset for the 92 3.3 IAC is as follows...

After connecting the neg battery, turn the ignition ON for 5 secs.
Turn the ignition OFF for 10 secs. Start the engine and check that it's idling properly.


It would reset eventualy just driving it, but it'll idle like poop untill it does. :2cents: