For the last few days my truck has had a miss at part throttle or cruise speeds. It only does it at real low throttle input no matter what the speed is. I checked and cleaned the IAC or IAT whatever it is but it didnt help. Everything is fine at idle and more than low throttle input. I was thinking maybee the mass air sensor or a fried plug but im not real sure.

 

Had the same problem, Dealer under warranty, replace two coil packs and several Spark plugs that fixed it!

 

i changed plugs about a week ago. Ill check them today and the coil packs

 

How do you check the Coil Packs??

 

I think i read somwhere you crank the truck and unplug one coilpack at a time. If the idle varies its ok and if it doesnt then youve found the bad one.

 

That sounds kind of barbaric, or rather simplistic… I was hoping for an electrical answer, like use a “VOM meter” or something like that! Thanks.

 

Post results please! Mine does the same thing, worse now than ever. When you give it gas though, she goes, no missing. It's mystifying as it can't be a fuel issue, and if the coils were bad, why does the miss go away?

BD

 

Had the same problem for years, just learned to drive around it.
Dealer couldn't find any problems and said they couldn't just start replacing parts. Never got SES light. Mine is a 2000. The thing I see we have in common is the color, white

Mike

 

I have a white 99 and mine does the same thing,

 

Well it looks like a white thing guess the best color has to have some downfall. Hope its all good cause the boost is getting turned up some more next fri

 

I had that problem when I was running Denso plugs, trashed them for NGK TR6's and no more miss.... JR

what kind of plugs are you running?????

 

FYI: Slight tip in throttle seems to be more of a lean mixture. That may have some bearing on your diagnostics...


I would have said fuel pump, but when mine cracked (the outlet of the pump) it went from poor part throttle, to almost unable to drive it. There's a low and high speed setup on the fuel pumps.

 

This all started when i added the ported eaton. So i guess it leaned it up at Tip in. But doesnt the computer add more fuel when neccassary at tip in? Im in for a reburn now anyway since im puttin a 2.8 upper on tommorow and filling up my bottle for the first time

oh and im running ngk tr6's @ .035

 

Mine does this too. I changed out my Denso IT20's for NGK TR5's and it got better for a day or so then it was back worse than ever. I suspect its the plugs or O2 sensors. I have IT22's on order and new Denso Sensors too, hopefully that will solve the problem.

Eric
Black 99L

 

Hey Eric... where ya been? out to sea or somethin?? Stop by the WashLo forum at NLOC....JR