So for the past several years I've been driving with misfires, bogging, shuddering, backfiring etc etc etc. I've done everything to remedy. Nothing really ties the faults together, and no common fix works. EDIT: Codes are misfires on 2 cyls (never the same 2) and one random misfire.

Its got the symptoms of one or all of the following:
Failed VSS
Failed TPS
Fuel issues
Clogged cats
Vacuum leaks
Bad plugs
Bad gas
Bad wires
Bad luck
You name it

Everything aside from the valves are new so I just decided to give up and "drive around it" - much like a few others, when it acts up I can let off the gas and quickly re-apply the pedal, gradually push the throttle until the stumbling stops or it downshifts, drive hard manually and it'll run good. It's not a show stopper, but annoying as hell.

So... I fired up the truck this morning because we got 6" of snow. Let it warm up for a few minutes (nothing unusual) and get on my merry way.

WOULDN'T YOU KNOW, THE ENTIRE 60 MILE TRIP (1.6hrs) THE TRUCK DROVE LIKE NEW. My brother has a perfectly running 02 and mine felt like that. ???!?!?!?

The throttle was very touchy, it had gobs of power, shifted correctly, didn't smell like gas, didn't shudder or stumble on the highway, and required no oddball bull**** I normally have to do to work past the misfires/loss of power. I didn't want to ever get to work!!

WTF?!?! I've owned and driven the crap out of this thing for over 3 years/30K miles and have NEVER felt what it's like when the damn thing is running correctly. WHY??? HOW???

I didn't add gas, I didn't sink it in mud, didn't punch it, didn't do squat. It just ran right. I know it will start acting up later and I'll get pissed - but now I'm wondering exactly what the heck is going on. It's almost funny now.

Lets say I had a sticky valve or valves. Could they someday fix themselves? I've done seafoam in the tank, done it in the vacuum, run only 93... it SEEMS like I've had more better days lately, but how likely is it something broke loose? Probably not huh..?

 

Yep 6" of snow will do that! Too bad it will run that well only with the snow. May I suggest you look up "Super Plow" and get one?
But seriously, I think that sticking valves is the most likely. Have you changed the oil?
The Shell Rotella is awesome to degunk the engine, the seals might leak for a while when the gunk is removed from around the seals but then the seals swell up again and the leaks stop.
If you are due for an oil change, switch to the Rotella and see what happens.

SD

 

Yeah - honestly if the truck runs like this because of the snow, I'm moving to Alaska! lol

Thanks for the input. I changed the oil about 500 miles ago. I use Valvoline Maxlife. I did an ATF flush at about 90K when I bought it. I'm at 124K now running this oil since the first change. It did leak a bit at first, and has stopped mostly - but I still drip around here and there. Mostly from the freakin front cover. :/ I hear great things about Rotella - just never thought to change it at this point.

MAYBE I'll get lucky and the truck will keep running good when I get off work... Fingers crossed.

 

Some Limey in a old airport hanger in GB is laughing his *** off at you!

 

If it has ran like that since you bought it it could have very well be excessive engine sludge and you had a sticky valve or 4.
Using the proper grade of gas and using a good oil and changing it like you should could very well have cleaned things up.
If it aint broke dont fix it.
I also use and swear by Rotella.

 

That's what I was thinking (hoping) - but the misfires returned yesterday on the drive home. I suppose that rules out the valves... Darn it!

I have a new oil pan gasket and front cover gasket waiting to go on. When I do that, I'll check the guts for sludge and see if/how bad it is. I don't think I should pull the head if I'm not 100% confident it's the valves either. Maybe this is something electrical somewhere... man I hope not. But I guess it could be worse; it's not like I can't drive it.

 

you sure its valves and not preignition, the cold would help the preignition.

 

I was kinda thinking a timing issue as well, possibly a faulty coil that just won't completely stop working. I have seen them break down internally to the point they barely had enough spark to make an engine run but still not completely stop working.

 

yea if you are misfiring the first 3 things would be plugs, wires, coils

 

Thanks for the continued input. To add some info:

Coils were replaced (with new) ~3k miles ago (tossin money at it)
New magnecore wires @ same time
Plugs then and more recently
VSS is new
TPS is new Battery and grounds new/good
fuel pressure is good/holds (filter is new)
Issue exists regardless of temperature

The only faults I have are the cyl specific misfires and the one random misfire. I had a downstream O2 fault, but new O2's cleared that.

I have a new coolant temp sensor as well - I assume installing that can't hurt. I thought maybe it was puking fuel because it thought it was cold... not sure though.

There was a guy selling a D1 5 speed ECU local a while back. He said the 5 speed ECU makes a little better power, and is compatible with an auto trans truck. I've looked at my ECU pins, and they look good... But would it hurt to try a different ECU just for shats n googles?

Justin