Bucking/hesitations And P300 Code

[zlthomps]

Hey guys, I'm getting a weird bucking or hesitation between 50-55 mph in the Truck under very light acceleration. If it starts bucking, and I punch it a little to get it to down shift to 3rd it stops bucking and pulls strong. Also from a stop going through the gears normally, or full throttle it's fine and pulls strong.

 

Also I got an intermittent P300 which is a misfire. The code went away on its own though, however I'm still getting that hesitation at highway speeds. A few things on my list to check are engine grounds, plugs and wires, any other thoughts? I really don't think it's the transmission although I suppose it's possible (Truck has only 76k on it). Not sure if this would rule out the tranny, but with the truck in 3rd gear on the shifter I was able to duplicate the bucking.

 

Truck is a 2000 Silverado LT Z71 with 78k Miles on the clock. Truck is totally stock.

 

Thanks for any help!

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Sounds like a coil pack going out. But, it could also be the plugs and wires. My original plugs and wires on my 2001 lasted 130,000 miles and were still running just perfect when I decided to replace mine.

[minibike132]

I'd be looking at the MAF, just a hunch.

[zlthomps]

I'd be looking at the MAF, just a hunch.

 

Hrrm, Thanks for the ideas guys. Ill do new plugs and wires, and pull the MAF and clean it up.

 

Thanks!

[ChevyTech77]

Could be a dirty injector too. I have seen a lot of issues with water and garbage caught in the fuel rail's of these trucks and it plugs up or takes out injectors. Most ignition misses may lessen/get better under high load but are

usually always there. Fuel misses act more like you describe.