GMC ENVOY 1999

wrote:
> On my 1999 GMC ENVOY 180,000 i keep getting P0301 misfire code. Things i changed spark
> plugs 3 times,all cords, evap canister, evap purge solenoid, ignition coil, distributor
> cap and rotor. Cleaned EGR valve. Car is still idling rough (not as bad as before) and
> P0301 still comes up? What else can I do???? Any suggestions I don't have much money.
> So I'm DIY-ing it with a small budget. Need it to pass emission. Thanks

No one reads alt.gm anymore.
Added rec.autos.tech.

Check for vac leaks... hoses, manifold, etc.
Take a look at the injectors.

Paul in Houston TX wrote:
> wrote:
>> On my 1999 GMC ENVOY 180,000 i keep getting P0301 misfire code. Things i changed spark
>> plugs 3 times,all cords, evap canister, evap purge solenoid, ignition coil, distributor
>> cap and rotor. Cleaned EGR valve. Car is still idling rough (not as bad as before) and
>> P0301 still comes up? What else can I do???? Any suggestions I don't have much money.
>> So I'm DIY-ing it with a small budget. Need it to pass emission. Thanks
>
> No one reads alt.gm anymore.
> Added rec.autos.tech.
>
> Check for vac leaks... hoses, manifold, etc.
> Take a look at the injectors.

Vacuum leak is possible but won't usually cause a single cylinder miss.
Swap the injector to a different cylinder, they are known for shorting
internally, if the miss moves replace the injector.
If it doesn't move run a compression test and a leakdown test on it to
be sure you don't have a burnt valve or mechanical problem, both tools
are available as rentals.

If you want more exposure visit www.2carpros.com and post the info and
question there.

--
Steve W.