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1997 GMC Suburban missing at 55-65 MPH

This is a discussion on 1997 GMC Suburban missing at 55-65 MPH within the Technical / Maintenance forums, part of the General Discussion category; 1997 suburban with 7.4L is missing between 55-65 mph. has no codes. I took it to the chevy dealer and ...

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    1997 GMC Suburban missing at 55-65 MPH


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    1997 suburban with 7.4L is missing between 55-65 mph. has no codes. I took it to the chevy dealer and they can not fiqure any thing out. has new plugs, wires, cap, rotor, fuel filter. pulls 50-52 lbs fuel presure. I can fiqure this one out. Any help would be nice. Thanks

  2. #2
    loose nut behind da wheel JeremyB's Avatar
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    Re: 1997 GMC Suburban missing at 55-65 MPH

    Does the miss go away if you get on the throttle, misses only at light throttle? Is the fuel pressure reading key on engine off or at idle? Its a little bit low if its key on engine off

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    formerly 99-2door Sinister C3's Avatar
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    Re: 1997 GMC Suburban missing at 55-65 MPH

    I had a 97 Sierra had the same problem. It was the coil, but I have heard several people with the same problem say cam sensor.

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    Re: 1997 GMC Suburban missing at 55-65 MPH

    Jeremy,
    Yes, it goes away when you hit the throtle. only seems to do it at crusing speed. thought it might be the tranny slipping but had it checked and it was ok. the fuel presure runs 50+ lbs both ways. I know the 5.7 need @ least 58 to even start, but was told the 7.4 @ 50 lbs is fine. hopefully this is correct. Thanks for your advice it is much apreciated. let me know if you have anything else. I have allready had it at 2 shops, and they cant find it either.
    Last edited by emmjlm; 12-10-2009 at 08:02 PM.

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    Re: 1997 GMC Suburban missing at 55-65 MPH

    Quote Originally Posted by 99-2door View Post
    I had a 97 Sierra had the same problem. It was the coil, but I have heard several people with the same problem say cam sensor.
    I will look into this. Thank you.

  6. #6
    loose nut behind da wheel JeremyB's Avatar
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    Re: 1997 GMC Suburban missing at 55-65 MPH

    It may be caused by the distributor being set wrong or a worn distributor gear. With a scantool hooked up, have the cam retard or camshaft offset checked, it should be 0 degrees +/- 2 degrees. I am sure there were some issues with the 454 injectors too, so you may want to search the site and see what problems they caused

 

 

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