99 5.0 lacks power

[maximum123]

well i went through deep mud.
she lacks power above 3500rpm, and check engine light.
cleaned mas-air, t-body, air filter, new plugs, injector cleaner.

Whats next?
egr?
i wouldn't think the fuel filter is dirty as new fuel injected models have filters designed for the life of the truck.

 

[Howard]

What was the code from the CEL?

 

[DarkFox1]

above 3500? why you revin. so high? you must drive like I do.

my truck lacks power too.. only no cel.. what codes were found from this? thats probablly the only real way you're gonna be able to narrow your search w/o randomly replacing things that you think MIGHT be the culprit.

also.. if you went through mud.. have you thought about fluids? tranny fluids, diff. fluid, engine fluids.. that sorta stuff? might wanna try somma tat

 

[Jason_25]

Probably has little or nothing to do with going through deep mud.
Get the codes read and tell them to us and we'll go from there.

 

[maximum123]

lean

shows o2 reading lean both banks last i checked

 

[Howard]

Try just resetting the computer (disconect battery for about an hour then start and drive around in normal style). See if the codes come back. Could be a leaking inlet manifold or just the fact that you cleaned the maf.

 

[maximum123]

hmm

tried that..

 

[Howard]

That leavse something like the fuel filter or a lack of pressure ie: pressure regulator or fuel pump. I believe that the pressure can be tested at the fuel rails. Hope this helps.

 

[DarkFox1]

ya know.. I had a reading done on mine.. the o2s showed both banks were running rich.. but I never had a CEL.

was this an overnight kind of thing? or did it just start slowing down over time?

 

[maximum123]

well at first you could hear the lean condition (ping) and it had a miss. Then after 1000miles or so the power loss was more noticeable. seems like the computer is pulling timing to compesate for the lack of fuel. i wouldn't think that the fuel system is clogged since it's a closed system (only open at the filler tube). any ideas?

 

[DarkFox1]

true.. and I agree about your thoughts on the computer.. the computer tends to overcompensate and sometimes can even mask a problem as another problem by doing that.. I wish it wouldnt.

well, if its lean, you may want to run some fuel injector cleaner in there, I mean I know its a closed system and all.. but.. it'd be worth a try. also.. do you often get gas at the same place? this is a long shot theory here.. but you think maybe you have had some bad gas in there?

btw what kind of mileage do you get? and what octane? as far as I know the 5.0 is designed to run no more than 89.. if you run 93 for too long, it can damage the engine.. or so I hear.

 

[Jason_25]

How is the idle?

Definitely run a fuel pressure test and compare it with factory specs for YOUR year truck.

Also, it wouldn't hurt hurt to take a look at vacuum pressure too.

 

[aldive]

Originally posted by DarkFox1
.. if you run 93 for too long, it can damage the engine.. or so I hear.

Not.

 

[maximum123]

i put some injector cleaner it but haven't ran it all out, about 150 miles. getting about 12-15mpg running 93 since it started acting up.