hey
im a newbie and have a problem with my bosses 02 excursion... im not a ford guy and all new vehicles kinda suck to me but its a job so i gotta do what i gotta do...
anyways this things got the 6.8 in it and it has a really weird problem... first ill say he removed the cat so now it throws codes for the O2 sensors being LEAN....
anyways, its developed a new problem... when its cold it will run from WOT without a problem. but as it gets hotter it it will cut out and not rev/pull/gain rpms at WOT... it doesnt shift, it just sits there and sputters till ya let up on the throttle a bit then it works perfect... as it gets hotter the problem gets lower in the RPM range...
any help ya can give me would be helpful.. thanks

 

Sounds like a misfire. Scan the codes. There might be a stored code telling you what cylinder it is.

 

it would have to be a mis-fire on EVERY CYLINDER cause it DIES and will no rev/gain speed/shift when ya stomp it..... no codes except for the o2 sensors and missing cat....

 

Possible fuel filter dirty, or low fuel pressure. Run a fuel pressure test.

 

we've ran the fuel pressure test twice now.. the first time it came right up to 30psi once truck was started and stayed there while driving/WOT/engine bogging...
i checked it again the other day and it took 2-3 minutes to start coming off 0psi while running.. it came up to 28-30psi slowly. truck idled/revved perfectly fine...

boss man sent me a txt saying its the coil packs and that they are weak ... has new ones on the way for me to replace come tuesday. ... his txt to me...

its the coils just ordered 10 new. its not getting enough spark which is making it run lean at operating temp. spark is not weak enough to set code but just shy of burning enough fuel.

makes no sense to me but how it acts i can see the no spark deal. but all cylinders at once ? that would be something else getting hot and shutting down not all the coils.... i know nothing about this new stuff so i have no idea what controls the coil packs....

give me a HEI anyday and this would have been fixed already....and not cost an arm and a leg....

 

What's a HEI?

 

It's one of those made up terms that Cheby people use. http://en.wikipedia.org/wiki/H.E.I.

Don't discount a misfire, computer controlled motors do some funny things. Sounds like you might be in limp mode(Forum search Limp Mode V10), these engines do that when they think they are about to blow up/over heat; makes them fire only about half the cyclinders and you get nothing out of the engine. Ask your idiot boss if you can have the receipt for the coils and go collect the refund, all ten didn't fail at once. Revert back to the old days, pull all the plugs, look at how each cylinder is firing, if you see one plug fouled, or five fouled(limp mode). Most of these Excursions only have to meet OBDI standards, so I doubt you have an O2 running aft of the cat, which means the LEAN code means you are RUNNING LEAN. Do another search(V10 Fuel Pressure), cause if it ain't running limp mode, it's probably a dying fuel pump. IIRC you should be about 39psi/34psi, turn-on/running.

Let us know what you find, hope this helps.

 

H.E.I. = when a normal citizen could actually work on their car and have it fixed in an hour instead of the dealers raping you w/ no lube.....

i agree it goes to limp mode but it only acts up when up to temp and youve driven around awhile to get it nice and warm... it runs fine at low throttle imput even when its acting up..... (might get worse the longer ya drive it though)
boss did say it was really bad with a load on the truck (boat)
it runs perfect temp wise (coolant and trans) . doesnt throw a code for this problem which is totally weird if its a missfire/low fuel pressure.... y wouldnt it throw a code for either of those ??? the truck/computer has to know theres a problem...

im more prone to believe its the fuel pressure reg.... anyone have a pic/diagram of where its located on this thing ??? im sure its nicely buried under/behind a bunch of crap...

its a good thing i wont ever meet the designers of new cars cause they would all be missing teeth...
designers after i meet them ---- >
except they wouldnt be laughing.

as for the fuel pressure neither excursion goes over 30psi... this one runs at 28psi or so and as i stated took forever to come up to 28psi yesterday...

keep the ideas coming....

as for the boss.. hes pooping money so it doesnt even faze him to spend it......

 

I can't figure out how to post a picture, I'll PM you and send you the diagram of the fuel system. Shopkey says 30-45psi, just checked on my Ex, it sits at 42 @ On, 38 @ running.

 

My vote would be fuel pump or relay.

 

Fuel pump. You'll see me type this once. I used to have a suburban and it did this very same thing. I don't care, if your fuel pressure is not up to par, it will act like that all day long. Mine would start and run fine cold, but once it got hot...FAIL!

 

Any new word on this?

 

relay for what (fuel pump?) and where is it located and how/why would it cause this problem ?

thanks for all the info folks.... will be working today and ill let him know what youve all told me.... ill let ya know what happens.....
thanks again

 

Not gonna be the relay, if it fails, you get no fuel pump power, so no pressure. I would look towards that fuel pump, or possibly a really odd acting fuel filter(it's cheap and easy enough to replace, might be worth doing it first)

 

not sure if we did the fuel filter on this truck yet or not... but ill let him know what you all are telling me and go from there... i hope its easier to replace the fuel pump on this than it was on my z71......