PO300 Error [solved]

[med71]

I have the random misfire code, PO300...sigh. My 2003 Envoy only has this code. One strange thing is that it won't rev past 3,000-3,200 RPMs. When the car is cold and started, it runs smooth but will not rev past 3,000. When the car reaches operating temperature it runs rough, missing, and will not rev past 3,000.

Here is what I've done:
1. New plugs and coils on all six (was planning on doing this anyway). The old plugs looked good and they all looked the same.
2. New fuel filter. Fuel pressure check showed 60psi at idle and under load with no fluctuation on the gauge.
3. I still have about half of a tank of fuel, and I haven't drained it. I did put heat in it just in case.
4. The gas cap looks weathered, going to order a new one.
5. Verified all wires and vacuum lines.

[Diacom]

Mark,

Give this Webpage a once over: https://www.700r4transmissionhq.com/p0300-chevy-trailblazer/

[med71]

I got this fixed last night. I went back through the coils, and I noticed that the purple insert on the #6 connector was inside one of my old coils. When I put the connector on the #6 coil, it bent the pins.

[Flyingfischer5]

Awesome! Glad it was something quick and easy! Good job!