Mechanics

PONTIAC FIREBIRD SENSOR PROBLEM

1990 Pontiac Firebird • 6 cylinder 2WD Automatic • 160,000 miles

On my 90 firbird 3.1 V6 it idles rough after warm up but drives in the higher rpms fine has a little surging while driving. But bad gas milage.I checked all vacum lines. Nothing leaking.I checked timing and it was at 16 before I adjusted to 10 btdc like book says with wire uncliped but when I reconect wire the timing jumps back up to 16 to 20 before tdc and surges between 16 and 20.I took off my egr and sprayed it out but no difference any ideas?
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Flamenbird87
December 26, 2010.




Check the fuel pressure if okay, clean out the idle air control valve, test the throttle position and manifold absolute pressure sensor-


Rasmataz
Dec 26, 2010.
Thanks for the help, where is the idle air control valve, and the manifold absolute pressure sensor located?


Tiny
Flamenbird87
Dec 27, 2010.
Ok I found the IAC valve and cleaned it put it back on no change. Still looking for the the manifold absolute pressure sensor


Tiny
Flamenbird87
Dec 27, 2010.
The MAP sensor is on the right side of the firewall


Rasmataz
Dec 27, 2010.
Thanks for the info and diagram this will help.I cleaned the IAC valve and check it it does work I took off my intake duct to the throttle and cleaned the butterfly asymbleI adjusted the timming again but when I did the timming I uncliped the single wire by the firewall the round wire connector not thee rectangle one and it droped the idle I then set timming to 10 degress before TDC but as soon as I reconnected the wire. The idle went up a little and the timming jumped to 12 to 16 again don't understand it the fuel pump is new so don't get this any ideas?


Tiny
Flamenbird87
Dec 28, 2010.
Try adjusting the throttle stop screw to drop the idle speed


Rasmataz
Dec 28, 2010.
I will try that, thanks


Tiny
Flamenbird87
Dec 28, 2010.
I droped the idle speed and it is at 600 when idling, Maybee I am diconnecting the wrong wire when I time the car. There are two single wire connectors one is rectangled and by the coil, the other is more by the firewall and closer to the fan motor and a round connector that is the one when I disconnect it my idle goes down. The rectangled one I disconnect and nothing happens to the idle. Wich one is the corect one?
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Tiny
Flamenbird87
Dec 29, 2010.
You have to disconnect the EST wire and then you check the ignition timing


Rasmataz
Dec 29, 2010.
Ok, Thanks for the reply, By any chance do you have a diagram that shows where it is located or the color of the wires, (wire diagram)?


Tiny
Flamenbird87
Dec 29, 2010.

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