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I'm new to the site...
I've been trying to repair/troubleshoot a rough idle and bank 1 lean code, I've done just about everything I've found online to no avail: plugs, 2 new cop's, 2 upstream o2,repaired exhaust leaks,swapped in junk yard mafs (it went rich on bank 2) replaced iac,check fuel pressure 33psi,fuel filter, I'm sure I'm forgetting a few items,
Just spent 2 hours smoke testing again ,because it acts like a vacuum leak....now I'm thinking timing, but want to make sure before I do....
High milage 325k don't know much history on it. It always sets lean code at idle using original maf, but when I put the other on it rich bank 2, both show g/s readings over 0.01 koeo
What engine do you have 5.4 or 4.2?
Fuel pressure was it running or key on engine off? Fuel pressure is low it should be 50 psi. Check fuel pressure regulator by pinching off rubber section of return line and see if pressure goes up if not pump is bad or you have a leak in fuel lines to rail. If pressure drops after key cycled and pump shuts off then you have a leaking injector. if not replace fuel pressure regulator if on fuel rail. If not on fuel rail it will be in the fuel tank with fuel pump. And before replacing pump check voltage at pump with it on to see if it shows less than battery voltage as this can cause a low fuel pressure issue as well.
Truck runs great, just a shaking idle. So I could probably rule out:
Blocked fuel rail,injector,
Unless I've missed something I'm leaning towards cats,or maybe timing set.
It's a 5.4
Had 32psi on rail koeo and running,snap throttle would fetch 35 psi. With regulator vacuum line off it went to 40 psi. Thus was one of the first things I checked earlier in the week ,searched online for fp pressure specs.,and found 28-45 was normal??...so I thought.
When I get home from work I can do more checking.
Will have everything you need from fuel rail pressure specs to testing components and wiring diagrams. You can get a subscription for a month for 20 bucks or 4 years for $44.
Googling it might get you close but this will be accurate info.
Ok new issue, installed new maf and bank 2 is giving rich code, high negative fuel trims bank 2 ,bank one looks good now.
New maf reads .05g/s koeo
6.71-6.89 idle, surges a little like always
(albeit it's technically in spec but on the low end )Also fuel pressure spec is supposed to be between 30-55 psi koeo on e series, f series and excursion with the 5.4L 2v. But rule of thumb for most of us is 50 psi on initial turn on and a rest pressure of what the regulator is supposed to regulate to. Typically this rating is on the regulator other wise need to look in service info for it.
It's a 5.4
Had 32psi on rail koeo and running,snap throttle would fetch 35 psi. With regulator vacuum line off it went to 40 psi. Thus was one of the first things I checked earlier in the week ,searched online for fp pressure specs.,and found 28-45 was normal??...so I thought.
When I get home from work I can do more checking.
I guess a compression check would be in order for my 05 F250 with the 5.4 3 valve I was able to get the plugs out yesterday without busting them off in there.I did it engine hot with impact wrench. I have 55k miles on the rebuilt Powetrain Poducts engine Sorry you found bad compression but at least you found it. What are you going to do?
No sign of oil, coolant, when I pulled intake, and none on the month old spark plugs....on #5 I had compression coming thru intake valve,but the other 3 that had low compression didn't. I didn't know the valves were adjustable on this engine.
Yep I should have looked that up but valve lash adjusters and roller followers are known to have the springs weaken (lash adjusters) and bearings fail (roller followers).
the other thing to look at would be cam lobes to see if excessive wear has happened just have to pull valve covers to inspect.
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