97 3.1L Idle Problems

Here are the facts.
97 Grand Am SE 3.1 L V-6
Changed the motor out for 3.1 L V-6 from 1998 Buick Century.
Changed all the sensors. Except Camshaft Position Sensor.
No vacuum leak, crank shaft positions sensor working, MAF working, as well as all other sensors are working properly except Idle air control. I have cleaned the seat area and I have an extra. Both test fine by using meter.
When I start the car it idles in the 1500 RPM range. I can unplug the IAC and it still idles fine but at 1500 RPM. I can remove the IAC and move the pintle to slightly open and replace it and leave it unplugged and it idles fine at 850 RPM. Plug the wire back in and the pintle moves open and the idle increases back to 1500 RPM. I have no miss conditions and I know for a fact that both cars were running fine prior to (3.1L in grand am was run way hot, 1998 Buick was plowed into the rear real bad) switching the engines.

Does anyone have any suggestions???

Ok, make sure you are using the grand am IAC.
Make sure it is set to 1 1/8 inchs from the base to the tip.

Also check the wiring to the Ecu :thumbsup:

I have checked and repaired all wiring. I had two open circuits because of exposed wiring at sensors. But that did not solve the problem.
Will set the IAC to the suggested depth and check her again this evening. I have used both. But I know which is which. I will post tomorrow with the results. Thanks

I adjusted the IAC pintle to 1 1/8 inches. And now it wont idle at all. I will be tinkering with an setting slightly less than that and so forth until I get something.

That IAC could be faulty, that would cause problems.

Might double check on vacum leaks too.

I played with the IAC depth and got the car to idle but it is running rich. The IAC tests fine with both sides showing the same resistence with the ohm meter. And both IAC's I have showing the same ohm's.
Now when it idles the car slows and revs slightly to cause a small amount of motor movement. I do not have a vacuum leak as this was my first inclination and have a vacuum gauge hooked up to the diagnostic port on the main vacuum line. I have tested the vacuum in several places and it all pulls fine.
Something on this engine is telling the motor to give it more fuel. This is evident by either the higher RPM's and the running rich when I have gotten it to idle. And when I mean rich it will drive you out of the shop in just a couple of minutes. The code reader I rented from Autozone was brand new and showed no DTC's. But now that I adjusted the IAC depth before installing it, the check engine lite is on.

You need a full scan here to what is going on.

I hadnt yet taken this car in for a full scan, but I did obtain a computer for this car from the local scrap iron yard. The computer is from an identical car with the exact same options. Even has the first three numbers in the VIN the same and was made only a month after my problem car.
I plugged this computer in and the car cranked and gave me the same fast idle problem. I unhooked it and plugged the wires back into the original computer and now the car wont start. It is getting fuel but very little spark!
The other computer will allow the car to run but the battery light and the theft light are on!
Any help to get this back to original computer and get these lights off so I can haul this car in for a full scan will be greatly appreciated!!!
Thanks

Well doesnt sound good....

You might try a 11 minute security relearn procedure.
With the ecu you want to use in, turn the key on and attempt to start, leave the key "ON" for 11 min, then off for 1 min. Then repeat 3 times

Usually when changing an ecu you need to do a security relearn, cant believe it even started when you swaped them. Never worked that easy for me..... :(

Hope that helps.

Okay! Will do and get back! Thanks

Well, no go!
I am certain that the security is the problem. I am giving up and loading this thing on a trailer and hauling it in to a shop. Gonna just kill my ego since I have always been able to figure out these problems with a little input from here and there. Will post back info on what the shop finds as the problems!!
Thanks

97 Grand Am SE 3.1 L V-6
Changed the motor out for 3.1 L V-6 from 1998 Buick Century.
Changed all the sensors. Except Camshaft Position Sensor.
No vacuum leak, crank shaft positions sensor working, MAF working, as well as all other sensors are working properly except Idle air control. I have cleaned the seat area and I have an extra. Both test fine by using meter.


The engine swap is possibly another problem.
One of the sensors or somethings not conntected properly.

And as Max said, you need a full scan to find out whats gooing on. :grinyes:

Good Luck !!