Question about 1998 Chevrolet Tahoe

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Hesitation under load ,creating a misfire code that clears in three drive cycles

Engine runs great except when regaining speed after a downshift to pass or go uphill. hesitation and loss of power triggers a misfire code that clears in three drive cycles. have changed plugs ,wires, cap, rotor, entire sfi, fuel and air filters.

Posted by katfig69 on

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  • Anonymous Nov 18, 2008

    I have the exact same problem on my '03 Focus and before I spend a lot of money on a bunch of parts, I'd appreciate if someone can help me out

  • joecyr Dec 02, 2008

    I have the same or similar problem without a check engine light. The car ('98 Pontiac Bonneville, 3800 MFI V6) will misfire and buck at low RPM (1200-2000) under load until the transmission downshifts. Adding more throttle, but not enough to downshift, aggrivates the problem. I ran hightest gas on one trip to the mountains and reduced, but not eliminated, the problem. I've had this problem for 2 years now. The only solution is to quickly punch the gas pedal and force a downshift or manually downshift the car on hills.

  • 1pur1ty1 Jan 07, 2009

    2001 Tahoe. idols fine, level ground accelerates fine. Changed plugs & wires and fuel filter. Fuel filter was especially dirty so I changed it again 6 weeks later and that one was even dirtier. For the most part it drives fine with a slight hesitation when engine is cold but can not go up steep inclines. I guess it's time to take it to the shop and let them figure it for me. Any ideas?

  • rodney850 Mar 19, 2009

    My 97 Lasabre problem is similar (P0300 Random Misfire), runs perfect until I get to 55-60 and slowly accelerate or go up a hill. It stumbles and will not accelerate until I punch it putting into passing gear. Fuel pressure OK, new plugs, wires, fuel filter.

    I am starting to think my problem might be a Ignition Control Modual or EGR. ???

  • Marvin
    Marvin May 11, 2010

    Have you tested the fuel pump for proper pressure? How about the crank shaft position sensor? Is it a random misfire, or is the code always for the same cylinders? All this info is very important to get to the root cause. The Chevy dealer has electronic test equip. that can be taken along on the road test to record the problem, then the tech can download it and decide the problem area to work on, you are wasting allot of money on parts that are not causing the problem.



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Problem is almost always plugs, wires, or coils/ICM. I have seen all three, they all act exactly the same with the symptoms you all describe. Sometimes CEL and code are present, other times not. Start with cheapest solution and work your way up (plugs & wires, coils, then ICM) The coils can be tested with a spark indicator individually, plugs visually inspected. Most auto shops can test the ICM.

Good luck!

Posted on Dec 16, 2009



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I belive the dealers have a T.S.B. ( tech service bulletin) on a issue close to this. I belive they re flash the ecm as the repair. Just thought you might check into it. Hope this helpes.

Posted on Jan 25, 2009

  • Anonymous Jan 25, 2009

    You might also want to check the egr system. It could be leaning out one cylinder causing the missfire. just a after thought.




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Egr valve port hole have to remove the intake to clean but that's my problem rite now on a 4.3 vortec the port hole gets cloged with carben not slowing it to work properly.

Posted on Jun 07, 2011

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the web page was:

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