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Thread: fighting a 95 blazer with cpi

  1. #16
    Electronic Ignition!
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    Quote Originally Posted by dave w View Post
    Maybe replace the spider assembly? https://www.rockauto.com/info/321/21...mary__ra_p.jpg

    Maybe replace the computer? https://www.rockauto.com/info/1/776395-fro__ra_p.jpg

    dave w
    already done. rebuilt ecm no change,reman injector swap between any of them same symptoms. new nos prom as well any combination of parts same thing what am i missing? grounds check good all the sensors appear to function as expected. even swapped some of those from the parts rig no change. how can i shorten the pulse width on the injector? seems to me that a quicker pulse would lessen the fuel its puking. and the main stumper why did it run to drive it in and just like that wont????

  2. #17
    Super Moderator dave w's Avatar
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    The injector flow setting will change the injector pulse width.

    For example an injector flow of 50 lbs / hr: we will say for argument sake is 8 milliseconds at 4000 RPM with an engine load of 75 Kpa.

    For example an injector flow of 100 lbs / hr: we will say for argument sake is 4 milliseconds at 4000 RPM with an engine load of 75 Kpa.

    Increasing the injector flow rate "makes the computer think" more fuel is flowing, so it reduces the time the injector will spray fuel.

    With the computer wire harness unplugged from the computer, and the injector connector unplugged from the injector along with the pulling the injector fuse, I wonder what the resistance is between ground and the two wires going to the injector are?????

    I also wonder what the resistance of the injector measures, measuring the two electrical prongs on the injector?

    dave w

  3. #18
    Electronic Ignition!
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    Quote Originally Posted by dave w View Post
    The injector flow setting will change the injector pulse width.

    For example an injector flow of 50 lbs / hr: we will say for argument sake is 8 milliseconds at 4000 RPM with an engine load of 75 Kpa.

    For example an injector flow of 100 lbs / hr: we will say for argument sake is 4 milliseconds at 4000 RPM with an engine load of 75 Kpa.

    Increasing the injector flow rate "makes the computer think" more fuel is flowing, so it reduces the time the injector will spray fuel.

    With the computer wire harness unplugged from the computer, and the injector connector unplugged from the injector along with the pulling the injector fuse, I wonder what the resistance is between ground and the two wires going to the injector are?????

    I also wonder what the resistance of the injector measures, measuring the two electrical prongs on the injector?

    dave w
    injector is no resistance both wires to ground open.

  4. #19
    Super Moderator dave w's Avatar
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    The generally accepted CPI injector resistance is between 1.30 - 1.70 ohms. A good quality / calibrated Ohm meter is needed to accurately read injector resistances. Odds are; a new in the box CPI injector will also read no resistance with a low quality / un-calibrated ohm meter?

    dave w

  5. #20
    Electronic Ignition!
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    I will check again with a different meter when I bring it back in pushed the frustration outside for a while

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