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Thread: Engine Surging After Installing Cleaned Injector

  1. #11
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    Jonathan - the first link you listed is the one I checked - part 102778. It seems to be functioning properly. Injectors have new rubber boots/seals. I'll take a look at the cold start valve. My schedule is busy for the next two days so I won't be able to get back on this until Tuesday.
    Last edited by lazabby; 05-07-2017 at 09:10 AM.
    Shannon

  2. #12
    Senior Member Bitsyncmaster's Avatar
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    A common problem with any engine work is your vacuum solenoid connector gets disconnected. That will cause idle problem if disconnected.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #13
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    Quote Originally Posted by Bitsyncmaster View Post
    A common problem with any engine work is your vacuum solenoid connector gets disconnected. That will cause idle problem if disconnected.
    Vacuum leaks are the #1 cause for hunting (surging) at idle. But ANY imbalance among the cylinders can cause it. That means each injector, intake and exhaust valve, spark plug, etc, MUST be tuned as closely to each other as possible. On one car the reluctor gap inside the distributor was not equal on every point causing an imbalance. Often when you fix one thing it may make the hunting seem worse because now the motor has become more sensitive to other imbalances. The place to start is to check and adjust all of the valves and do a cylinder compression test. If you can't get all of the cylinders within 5% you will never get it to stop hunting.
    David Teitelbaum

  4. #14
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    Quote Originally Posted by David T View Post
    Vacuum leaks are the #1 cause for hunting (surging) at idle. But ANY imbalance among the cylinders can cause it. That means each injector, intake and exhaust valve, spark plug, etc, MUST be tuned as closely to each other as possible. On one car the reluctor gap inside the distributor was not equal on every point causing an imbalance. Often when you fix one thing it may make the hunting seem worse because now the motor has become more sensitive to other imbalances. The place to start is to check and adjust all of the valves and do a cylinder compression test. If you can't get all of the cylinders within 5% you will never get it to stop hunting.
    One thing to remember, the car was running fairly well before I had the injectors cleaned. I think I must have knocked a vacuum hose loose somewhere.
    Shannon

  5. #15
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    The possibility exists that after cleaning the injectors, some are working much better than before. Before they may all have been working equally badly and now some are better than others. You could remove them and see that they all have good patterns and flow equal amounts of fuel.
    David Teitelbaum

  6. #16
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    Ok I got the problem solved. Before the injectors were cleaned the engine was tuned to those injectors. St least two of the injectors were stuck open and the others were not spraying well. Now that the injectors are spraying properly the engine was surging. I had to adjust the idle screw counterclockwise until the idle levelled out. Now it's idling well.
    Shannon

  7. #17
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by lazabby View Post
    Ok I got the problem solved. Before the injectors were cleaned the engine was tuned to those injectors. St least two of the injectors were stuck open and the others were not spraying well. Now that the injectors are spraying properly the engine was surging. I had to adjust the idle screw counterclockwise until the idle levelled out. Now it's idling well.
    Adjusting the mixture screw for best idle is not a good idea. You will most likely adjust to a mixture so rich the lambda unit is now beyond its control. Sure your idle will be smooth but your MPG and emissions will be bad.
    Last edited by Bitsyncmaster; 05-13-2017 at 05:27 AM.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  8. #18
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    Quote Originally Posted by Bitsyncmaster View Post
    Adjusting the mixture screw for best idle is not a good idea. You will most likely adjust to a mixture so rich the lambda unit is now beyond its control. Sure your idle will be smooth but your MPG and emissions will be bad.
    He turned the CO adjustment left which is leaner so that is not the case here.

  9. #19
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    Anyone have any tips on how to "easily" remove the fuel injector located on the driver's side closest to the front? The one that's blocked by the cost start valve?

    The car idles fairly well when warm but hunting when cold. *sigh*
    Shannon

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