My truck runs good around Memphis. On mostly flat roads. We were in the Lebanon area last weekend for the Supernationals and a few times when we were coming up a hill there was a definite miss. Usually when the petal was feathered to just keep up with the 55 MPH speed limit and not downshifting. If it did downshift and reved up, it would run fine.

Ideas?

 

Hi Fifty,


It could be one of your sparkplug coils gettin' weak.
You could also check the FPDM module; It's under the truck bed, above the spare tire. They are notorious for giving fuel issues intermittently, because they get corroded, etc...

 

I'm also going with low fuel pressure. Whether it be the pump, a dirty filter, a bad regulator, bad gas, or the fuel pump module. One of them is keeping sufficient fuel from reaching the engine during higher load demands. The easiest way to confirm this is to hook up a fuel pressure gauge and go drive up a hill. If by some chance the fuel pressure holds then the next thing to look at is the MAF sensor being dirty or bad.

 

Clean all contacts on coils and the connection plugs . Do you have new boots, new spark plugs . Use dielectric grease on each end of new boots . People try to use old boots but they don't realize the boot has to hold back 30,000 volts from sides of heads . Heat and age degrades them .
Misfires don't set codes until they last a long time . They are very hard on your cats which can cost you real money . Or make it jump time or worse .
The spark plug area is very touchy on this engine . Change them at or before 60k and use oem . Clean tip area of cyl to get that carbon out with carb cleaner . If it breaks some plugs coming out what do you think it does to new plugs being forced in ?
Don't use extended oil changes , 5k is enough . This engine runs phasors hydraulically with dirty engine oil thru paths that have screens and small passages . Combustion carbon is the dirt ,don't let it jam your engine up . Don't flush your engine it will jam it up . Been there done that .

 

Check it, if it's not on stand offs replace it with new design . It will cause you problems sooner or later . Dorman seems to be okay for this . Amazon !

 

I appreciate all the answers. Of course on the ride home from Nashville and to and from work this week so far has provided no misses. On a couple of hills on my ride home from work I tried to reproduce it. Going about 50 MPH and slowly ramping up to 55. Runs like a champ. Trouble is I'm about to put my kids in it so we can all go on a family vacation to St. Louis. Another hilly area. I don't want them to have trouble. I'm going to drop my spare and look at the FPDM. Changing the fuel filter is an easy fix. But I'm right on the line with the spark plugs. I've heard from 2 sources that the cutoff is Oct. 2007 for the newer stronger spark plugs that won't break. Mine was screwed together that Sept.! And since I bought used, I have no idea if the plugs were changed before I bought. It has 121K right now. And I really don't want to spend the $640+ price I've been given at a local shop.

 

And people wonder why we do our own work...go figure!

 

Might should start another thread, but has anyone done the Seafoam-down-the-power-brake-vacuum-hose on this late model engine?

 

Had the exact same issue a few years ago. Did a plug change, found this:

 

How in the world did this engine run like this?

 

I was going to do the fuel filter today, but I'm finding there is a 3/8" and 5/16" line diameter.

 

Brute force, strong will, and magic.

Don't waste your time/money on fuel parts until you check/do the spark plugs. 99% certain that is your issue though hopefully not as bad as mine was.

FPDM wouldn't cause a miss, it would completely shut your truck off due to lack of fuel and would not vary how it is running based on flat surfaces or "hill climbs" on roadways.

Fuel filter - again, if causing a problem it wouldn't do it on inclines and not do it on flat roadways.

 

This engine bad about loose plugs- typical failure ,damages boots/ cops .Plugs need 25 foot pounds with a torque wrench . People just believe they can guess it by hand . Do it right when you are in there. Hope it didn't cause any damage .

 

That's the cheapest parts and it carries 30,000 volts down thru head and keeps it from jumping to head . But time after time people don't change them , they can't see that high voltage jumping thru the boot . It only takes a pin hole or a little contamination .
The other thing is the carbon build up around the tip in the cly ,you know it breaks plugs coming out but we force new plugs thru it . Then we finally believe we got some bad plugs when we bought them. Clean those tip areas out with carb cleaner . No seafoam doesn't reach up there.

 

Lol, forgive my ignorance, but how TF does proper torquing prevent the entire end of a plug burning off into nothing?

These engines are just bad in general when it comes to maintenance, especially with the plugs, but I have to disagree (until proven otherwise) that an improper torque would cause what I experienced.