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Thread: '95 Century Odds and Ends

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    Senior Member Century7667's Avatar
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    Default '95 Century Odds and Ends

    Hello,

    It's been awhile...workin' for a living.

    Two questions:

    1) The 3100 powered a-cars had two cooling fans. Does anyone know what kicks on the forward fan? I was doing an underwood inspection when the inside fan kicked on (no AC running). A quick look at the temp gauge let me know she was warm enough (~220). So, I took the opportunity to try the A/C and the AC runs the same inside fan. So, I'm wondering if my outboard fan is not running, or something else has to occur for it to start.

    2) I've got an intermittent somewhat rough idle after the car goes into closed loop operation. I'm thinking O2 sensor, but I will break out the laptop to confirm that. Anyone ever pull that O2 sensor? Any words of wisdom?

    Thanks,
    Ken T.



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    Pontiac6ksteawd's Avatar
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    If I remember right, which I know little about the gen3 FI 60* engines, it kicks on when the temp gets really high.

    That being said, the cooling fans on my GEN3 60* in my Aztek come on together.
    Brian - Carpe Diem

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    Senior Member 85_Ciera_Rebuild's Avatar
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    Quote Originally Posted by Century7667 View Post
    I've got an intermittent somewhat rough idle after the car goes into closed loop operation.
    EGR?

    Brake Booster?

    Open Loop tends to have extra fuel added...but I'm not a Guru on how this was twitched over the years.

    On two different older EFIs (Bosch & Regina), Bosch used a fixed program for open loop, and Regina used values from Closed Loop runniing, when available.

    When engine is warmed up, if accelerator pedal is slowly depressed, say up to 4,000 RPM, and engine is smooth going up, then this would rule out a valve issue.

    Get a bottle of Techron and add to a tankful of gas

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    Senior Member CorvairGeek's Avatar
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    Quote Originally Posted by Century7667 View Post
    Hello,

    1) The 3100 powered a-cars had two cooling fans. Does anyone know what kicks on the forward fan? I was doing an underwood inspection when the inside fan kicked on (no AC running). A quick look at the temp gauge let me know she was warm enough (~220). So, I took the opportunity to try the A/C and the AC runs the same inside fan. So, I'm wondering if my outboard fan is not running, or something else has to occur for it to start.

    Thanks,
    Ken T.
    After an exhaustive search of the '96 shop manuals, I still can't give you any new specs. It says the main (puller) fan turns on at a coolant temperature of 230 degrees. Looks like that don't want nailed down other than that.
    I have found on ours that the secondary fan (pusher) turns on at very high head pressure with the A/C, somewhere when we are above 90 degrees outside (we top out about 110 degrees here for a few days in the summer). I believe it will also turn on if the PCM see the engine temp sensor as an open.
    The '96 shop manual claims the 2200 engines also have the secondary, pusher fan. I can't say for sure that is true, as I don't recall seeing one. I do believe the secondary pusher fan was added strictly because of the refrigerant change to R134a, though one was offered with the VO8 cooling option on the older cars.
    Jerry

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