Replaced cap,rotor,wires,plugs, the other day still have the original Distributor,pulled it last week to replace cam sensor, gear looks fine Truck has 300,000 miles on it, second motor 100,000.

 

Update, Did a compression test on cylinder #1 which is the cylinder misfiring Po301 and compared it to cylinder #5 both have over 120lbs of pressure, Pulled the valve cover and with the truck running applied presser to the valves in each direction with no change in rough idle. so I'm ruling out valve a bad valve guide. Question: can a faulty EGR cause a misfire in just 1 cylinder at idle without tripping a DTC for an ERG issue? and someone mentioned changing the distributor, Would that cause a misfire in just 1 cylinder? Any thoughts?

Thanks

 

things that would cause a misfire in cylinder 1 only are a bad wire, bad plug, bad injector

 

Then it sounds like my 6 month old spider unit has a bad injector. Plugs and wires are brand new.

Thanks

Anyone know off hand what the warranty time period is for a spider injector unit from GM

 

wire could still be bad check for spark from the wire and check the plug, your distributor could still be screwing you up

 

I checked the wire yesterday, throwing good spark and also replaced plug with a new one,
Truck runs fantastic, just misfires at idle. I'm going to throw in a new EGR valve and my next step will be a distributor, if that doesn't solve it I'll go to the injector, But being only 6months old and only misfiring at an idle I'm not sure about the injector, I've run a few bottles of the Chevron injector cleaner and also had the injector system cleaned but getting ready to throw in the towel !!!

 

you should take it somewhere and get it scanned with a bi-directional scanner so you can turn off each individual injector and see what the ohm reading is to the injector on that cylinder

 

sounds like a good idea, Thanks for your input Will update soon !!

 

95 = CPI = only one injector. The problem could be a stuck poppet nozzle though.

 

could be but he said he installed a new spider so wouldn't he have used the updated design ? I am just assuming I don't even sell the old design anymore Standard only makes the updated design with an injector on each cylinder