96 4.3W 4x4

Been searching the forums, couldn't find anything for this particular issue. Bought the truck last week with a P0300 and an Evap code (I forget the code). Only misfires during idle, runs fine when throttle is applied. IAC Valve? Just making sure so I don't throw unnecessary parts onto it. Plus, I don't think the evap code would make it misfire like this at least. Thanks!

 

Have you tried an injector cleaning? The poppet nozzles on these trucks like to gum up. The effects, in my experience, are more pronounced at idle than other engine speeds.

 

I'll be working on it this weekend, my time is limited after work to do this stuff =/ I'll look into that along with checking out the Ignition bits also. It's not affecting the truck itself, just a bit annoying at a stop light

 

Next time you fill up, dump two 20 gallon treatments of Chevron Techron Fuel System Treatment Plus into the tank before you start pumping the fuel. Drive it through that tank full and see how it goes.

You can also try cleaning the throttle body, MAF sensor, and EGR valve.

 

Been through the dreaded p0300 a while back for me it turned out to my distributor
Cap and rotor were burning due to water getting in
The cap since the distributor sits on the back of these engines water seems to get to them more than not give it a look and check, also check your fuel pressure as I've seen fuel
Pumps dying give a p0300 good luck and report back

 

Here's a bit of an update for everyone.

Read the monitors with truck running, Found that only Cyl 6 was misfiring. Pulled the plug, wrong size plug was in there! it was about 1 inch longer and it looked like the piston hit it and bent the top arm. It was completely sideways, rather than on top for spark. Changed that, but didn't change much

Checked compression, good. Spark, good. Fuel, good. Now i'm at a loss. I ran injector cleaner straight through the spider with no fuel. Helped it a bit but now after a couple days i'm back to square one.

Should i change out the injector? Any other possible options?

 

Before you go spending all that money on a new spider injector unit try swapping #6 with #4 and see if the misfire changes to the other cylinder..Thats just my opinion.. im fighting a misfire as we speak lol