'99 250 5.4 w/130k. Thought it was the trans, and problem was intermittent. Stumbled only under heavy load (towing uphill). O/D light flashed the first time, then never again. Without a load, would run well for 45 min or so, then stumble again (pull over and shut down for 10 seconds to get it to run right again). Now, engine stumbles consistently.

Tranny shop checked out trans, and said it was good to go. No tranny codes. Replaced fuel filter, cleaned MAF, fixed a melted vacuum line going to diaphragm on fuel rail, but nothing... still stumbling.

Throwing: P0171, P0174, P0135, P1130, P1131, P1150

Hooked up a fuel pressure gauge and showed about 30 psi consistently in Park and under heavy acceleration.

My limited diagnostic capabilities are running out... Any thoughts on what the next thing I should look at is? If it were a bad coil or connection, it would throw a "coil" code, right?

 

My fuel tester in action in a parking lot

YouTube - F250 fuel

 

coils 2 & 4 were replaced and it runs properly again...

 

Glad you got it figured out. Fuel pressure looks good.

 

The 171 and 174 are lean codes. I have them right now but we might have different problems. Glad your problems are fixed. I might need to do a fuel pressure test. Did you have all the codes at once or did they show up at different times?

 

My truck is stumbling now. Feels like I'm hiting pot holes when I lightly hit the gas. But when I hit the gas it goes away. Did you feel the same thing too?

 

I am having a similar problem. Mine is a 97 F150 5.4. It has new accel super coils on it and new plugs (about 6 months ago or so) It started running rough occasionally and then last night it was running rough and then the light came on. When I put my analyzer on it I got the P1131 code. I don't find a vacuum leak or an exhaust leak. I haven't had time to check the fuel pressure yet. Anybody have any suggestions?

 

have you re-scanned the codes?? See what is has been cleared what still remains.

willing to bet you still have a vacuum leak....the elbow on the rear of the intake for the PCV is a known location...but check the everything.

you may have more faulty COPs.

have you taken the throttle body housing off and gave it a good cleaning??...include the IAC. but clean the IAC with WD40,making sure the plunger rod inside is free. Clean the throttle body with carb cleaner, making sure the EGR ports there are clear.

 

It only has the P1131 code. I cleared it and it came back last night. Wouldn't a vacuum leak set of both the 1131 and the 1151 codes?
I have taken it off before and cleaned it. I haven't cleaned the IAC or the EGR.
Thanks I'll try those and let you know.

 

I took off the IAC to clean it and found the PCV elbow was sucked in and nearly plugged. I made a new one and cleaned the IAC, throttle body and intake that I could get to. I could not get the EGR tube off due to not enough time. On a good note the code has cleared itself out so far.

THANKS

 

Sounds like your gaining on it

couldn't hurt to check/change the PCV as well.

Made your own Elbow?? out of what? more details on that please

 

The code came back last night.

The PCV seemed fine when i had it out and cleaned it.

Ok I MacGyvered the elbow. I used a piece of heater hose, a piece of fat vacuum line, and the end of the old elbow. Along with a dab of silicone and extra wide black tape. I stuffed the old elbow part in one end of the heater hose and put the vacuum line in the other end with silicone and then wrapped it in black tape.

I think I need to just change that o2 sensor.

 

After talking to a mechanic friend of mine we came to the conclusion that it is most likely an injector.

 

Service engine light came on, O' Reilly scaned codes for free and getting lean codes P0171 and P0174. Elbow coming off the pcv valve was collapsed replaced the pvc valve hose and no more service engine light at least for now. Read in some post to remove several things to take off and install new one. For a 2003 F150 5.4L no need to remove anything to take off old or put on new one.

 

On the elbow, go to Advanced Auto. On their floor shelves, not behind the counter, is a PCV elbow marked for Ford ($10). It is too big on the end that goes to the PCV valve. I just cut off the old elbow at the PCV valve and spit on it for slight lubrication(cause it's tight!), and pushed the new one over that old piece.

That Damn PCV hose elbow is terrible! Mine was soft and had a large rip in it, and it was full of sludge.