Mechanics

CHEVY CODE P0108

1998 Chevrolet Blazer

Engine Mechanical problem
1998 Chevy Blazer 6 cyl Four Wheel Drive Automatic

Help, I have a code P0108. We tested the Map sensor and found it was bad. We replaced it and still get the code. I have check all the wires and found nothing wrong. I dont know where to go from here? There are no other codes. The blazer will start and run good when cold. Thats about 300 yards. Then starts missing very bad untill it stalls. The cat conv has been removed and fule pressure is good. The fuel filter has been replaced. Help.
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Jamesjam
August 14, 2008.



On the fuel tank there is a sensor that looks exactly like a map sensor. Its a fuel tank pressure sensor. Unplug it and see if it runs good. I have seen these short out and bring down the 5v reference on the map sensor causing it to die. Let me know

Tiny
Mastertechtim
Aug 14, 2008.
Will I haft to drop the tank?

Tiny
Jamesjam
Aug 14, 2008.
Ok I know I haft to drop the tank but is there a easier way?

Tiny
Jamesjam
Aug 14, 2008.
Ou dont have to drop the tank, you should be able to reach up and unplug it
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Tiny
Mastertechtim
Aug 15, 2008.
I found the sensor and unplug it It still runs like crap.

Tiny
Jamesjam
Aug 15, 2008.
Have you checked cap and rotor? Coolant temp sensor? If wiring to sensor and the sensor are good then check the egr valve for a piece of carbon bouncing around in it. Also lightly pull on wires to map sensor to make sure the wire is not broken inside the insulation.

Tiny
Mastertechtim
Aug 15, 2008.
The cap and rotorare new. The erg valve was pulled and clean and all the wires seem ok, I havent gone thru the check on the temp sensor, but I did unplug it and it didnt make any differance. I am at a total loss. Do you think I should perform the test on the temp sensor, even if it didnt make any differance?

Tiny
Jamesjam
Aug 15, 2008.
I would recheck test on map sensor and make sure all the voltages are correct. You either have a loss of engine vacuum at the map port, wiring from pcm to map or bad pcm I would suspect. Its hard to give a real accurate diagnosis without driving vehicle but the 108 we need to get to the bottom of. Do you have access to a scan tool to actually watch map voltage to see if it is working at all? Thats what I would do next.

Tiny
Mastertechtim
Aug 15, 2008.
Ok, after working on the wireing and going back over the everthing else, I dont have a engine code any more. I have run and run it no code. However, when it gets warm it still cuts out. I cant rev the motor. I did drive it and it went much further. I am pulling a spark plug to see the condition. Do you have any Ideas now?

Tiny
Jamesjam
Aug 17, 2008.
Plugs look good

Tiny
Jamesjam
Aug 17, 2008.
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