Question about 1997 Buick LeSabre

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Intermittent Misfire on cyl #4 1997 Buick Lesabre

I have an intermittent misfire on cyl # 4.
Not the coil, plug, wire. Tested for pulse on injector #4.

80% of the time, restrting engine will make it go away?
Then, when hitting brake or acceration will start again. Always a PO304 code.

Suspecting a intermittent failure or sticking of injector if that is possible??
Possibly a weak valve spring on cyl 4?

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  • William Buccheri Jan 23, 2009

    yes, with a plastic intake maifold

  • William Buccheri Jan 23, 2009

    Getting ready to go to Pull-A -Part to get injector and replace.

    If this don't work, try a compression test on cyl#4.

    Fortunately I can induce misfire by holding break, and goosing the engine.

  • Roberta Smith
    Roberta Smith May 11, 2010

    well read up on that page and try the test and see if that does in fact make a difference


  • Roberta Smith
    Roberta Smith May 11, 2010

    I realize this is a ford they are talking about but please read this

    is that a 3.8 L motor by chance ?




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How's your coolant level? The intake manifolds on the 3.8L engines are prone to breakage at various locations causing coolant leaks into the crankcase and vacuum leaks on intake ports.Removal of the upper intake manifold will be necessary for inspection. Also, check for vacuum leaks at various locations on the outside of the intake manifold using WD-40 or brakeclean/carburetor cleaner sprayed hoses, non-electrical components, at the base of the manifold etc. As for a faulty injector, not likely but if you suspect one you can always swap the suspect injector with another on the engine and see if the misfire follows the injector. Just be sure to relieve the fuel pressure before servicing. Hope this helps.

Posted on Feb 10, 2009


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    hey thanks for bringing me up to speed. ive been working on many other problems but with your great explanation i remember.
    we need to check the compression on that cyl. and compare it to the compression on 2 other cylinders your choice.
    but before you do this get a can of carb cleaner . and with the car idling spray around the intake manifold in the area of #6 cyl. what we are looking for is a small vacuum leak that would also act like this. with the engine idling and spraying around the intake the engines idle sould not change and if it does when you spray you have an intake leaking.
    let me know how it turns out.

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