Search Auto-Repair-Questions

Tuesday, April 07, 2015

have a 2002 buick lesabre 3800 engine misfire

has check engine light on and it FLASHES. it says p0300 which is a random/multiple cylinder misfire detected. so far i replaced all spark plugs and wires. i replaced fuel filter and put emergency brake on and put in reverse (it only misfires when in gear not when idle) and i sprayed all vacuum lines with wd40 which is supposed to make it stop misfiring if its a vacuum. cant seem to find problem. what else should i check? i thought about fuel injectors but is there anyway to test? i have some fuel injectors from a 1995 Buick Lesabre. would they probably hook up and work if that's problem? it has coil pack but can they be tested?


  1. i believe they can.. it has 3 of them... ignition module is under the coil packs and not a cheap part... if your in jackson ive got a coil pack you can use as a test part

  2. if its a throttle body injection system, you could be losing vacuum from a defective throttle body gasket.

  3. oh the other thing I forgot to mention on that is mIne hAd a weak fuel pump That caused that code to appear

    Mine is a 01 lesabre

  4. Ok today we replaced spark plug wires abd yesterday plugs. We got a spark ignitor to see if it sparks. We thought about coil pack or injectors.

    Fuel pump seens to ve good. Never had any trouble starting it. Checked vacuuns sprayed carburetor cleaner around vacuum to listen for change still nothing

  5. GM products have a bad reputation for plugging up their fuel filter, they will run bad, stall, and not start so check that too, it could very well be that