I thought maybe I was imagining a problem with my truck till I found this... I have a 2001 Supercab Lariat with a 5.4L and it's doing the exact same thing yours is South... Only mod on my truck is a magnaflow exhaust and it's been on the truck since 37,000 miles and I know have just over 130,000 on it. I'm also in the process of testing sensors... Got a leaking EGR tube (which sounds alot like a broken manifold bolt)I'm changing this weekend to see if that may help. I'll let you know

 

Please keep us updated...

 

After day two in the Ford Dealership shop (and several different Ford techs working on it) we still have nothing in the way of a solution to the issue. As a matter of fact they can't even figure out the problem.

The shop foreman called me this evening and said they have checked and double checked pretty much every possibility and can't find anything that isn't doing what it's supposed to. They thought they figured it out earlier today when they unplugged the Knock sensor - the truck came to life for a few minutes and would light the tires up in a power brake like it used too. That lasted for about three good power braking attempts in the shop, on the fourth try it bogged right back down like it was before. They tried a couple more times after that with similar results. The Ford hotline they can call for help won't help because the truck has aftermarket air filter, an aftermarket exhaust, and oversized tires (from what I was told). I don't know what the hotline is, but apparently they are the genius side of the Ford tech department.

He said he is going to recheck a few things tomorrow morning (he mentioned exhaust backpressure and a couple of others), but said he is honestly stumped. He said in the twenty years he has been with Ford as a tech he has never seen this - in his opinion something on the truck is going wrong, but it's too early for it too show up in diagnostics. He said as long as I am not in a hurry he will figure it out, but it's gonna take some time.

I told him if he can't figure anything out by tomorrow afternoon, I will come get the truck and hook up to the trailer I usually pull (3500# or so) and bring it back to them so they can see what it's doing under its usual load. The problem is MUCH more obvious when a trailer is back there. He seemed to think that would be a good idea and said he would call me around lunch with an update.

I feel like beating my head against the wall on this one.

 

Unplugging the knock sensor eliminates the signal to the PCM. After a predetermined amount of time the PCM will see that the knock sensor is off line so to speak and retard the timing to save the engine from unmonitored knock. Have your friend lend you a known good sensor and plug it in then duct tape it to the firewall so it cannot detect knock. If the engine comes back to life you may have valve train noise that is retarding the timing or the sensor is kaput.

 

we have a "tech line" at land rover, and its a small call center that we can call when we get stumped on something, this small group of guys hears about all the really messed up cars across the country, so they are the go to guys to know if its a problem that has been seen/fixed before somewhere else

 

That would make sense seeing as how the truck ran fine after immediately unplugging it, but after a couple of power braking attempts it went right back to what it was doing.

 

Check if you have any lost tools such as a socket,wrench, nuts, bolts, etc. laying under the intake manifold in the engine valley. They can rattle around and give the knock sensor a false sig to the PCM.

 

I know I personally haven't lost any tools there - the truck has always been serviced by a Ford tech (either at his shop at the house or at the dealer, but always the same tech). I will have them double check for something along those lines though.

What else would cause excessive valve-train noise?

 

Damn, there's another way to check that, but I can't think of it. There's a little block wired into the harness. It's just below the shift solenoids, pinned to the firewall. I can' think of what it's called at the moment.

 

i would think with what they figured out by unplugging the knock sensor they would have tried replacing the knock sensor...

 

You would think if the knock sensor failed, it would throw a code.

 

yea, but this truck apparently isn't playing by the rules...

 

Yea, this is what I was thinking of -

Octane Adjust Shorting Bar

The Octane Adjust (OCT ADJ) shorting bar is used to retard spark timing. Removal of the shorting bar from the in-line connector will typically retard spark three degrees.

The purpose of the OCT ADJ self-test is to check the state of the OCT ADJ shorting bar. A Diagnostic Trouble Code (DTC) will be present if the shorting bar is removed or if there is an open circuit. The OCT ADJ shorting bar is similar in shape to the SPOUT in-line connector.

DO NOT remove the shorting bar unless directed by a Technical Service Bulletin (TSB).

If you don't have the bar, your timing has been retarded.



Like I said, it's right below the solenoids. Might want to check it's condition.

 

I reread each of your posts. Post # 1 you say this is not your daily driver it sits and is used to pull your trailers on weekends. Is it possible that the gas in the tank is getting stale lowering octain and causing detontion? This would cause the spark knock sensor to react giving you a power loss and not throw a code.

Post #25 still sticks with me. I just drove my wifes MKZ on I 94 for about 20 miles at 80 MPH stopping several times once off the freeway until I pulled into my drive.(I was thinking of your problem while driving) I grabbed the garden hose and sprayed the front and rear wheels a small amount of steam rose from the fronts very little to none from the rears (4 wheel disc). I then took my truck out onto the main road 1/4 mile from my house and drove it hard for two miles stopping several times hard as I returned to my subdivision, grabbed the hose did the same thing with the same results. There was no excessive steaming boiling water whatsoever. Maybe I'm wrong but your discription of how yours reacted( boiling steaming water) just sounds excessive to me especially for the rear brakes. I don't mean to beat a dead horse here but the remarks in these two post stick out to me as potential problems. Take care.

 

JBrew - I am going to have them look into this ASAP.

Dynotech - I only drive it on the weekends, but I usually keep between a half tank and three quarters of a tank in it. I typically go thru a half to two thirds of tank when using it. None of the gas sits in it for more than a week.

I had the brake system checked - they didn't find any drag whatsoever. Up on the lift, the mechanic was able to free turn all the wheels without any issues at all (and he wasn't a muscle bound guy by any means).