I've been having some issues with my '04 6.0L Excursion 4X4 for sometime. I've experiened injector stiction for longer than I should have put up with it, but did not know that just changing to 5-40 synthetic oil would fix the symptom. I've recently been doing much research on what may be the underlying problem and think it may be the wiring harness. How much would it cost to have a reputable mechanic do the change out if it indeeds needs it? How much does the harness itself cost?

Symptoms after changing to synthetic oil.
1. Injector stiction is gone.
2. Stumbled last night at 50 mph on the way home from dinner. I was thinking it could be a fuel issue.
3. Twice did not accelerate at a dead stop for about 20 seconds. It was like the truck did not know the pedal had been depressed. (not turbo lag)
4. Twice have been stranded after 3-5 stops of short in town driving. Truck is currently at Sears. No start situation after trying to find 36mm socket to change out the fuel filters. It has been some time since this has been done and first time I was going to do it myself.

After changing oil 3 weeks ago I had one stumble at 35 mph suspected fuel issue. Then went on a 700 mile round trip fishing trip, pulling a 4000 lb boat. Truck had exactly zero issues on trip. All the above issues have happened in the past 7 days since being back in town.

 

This is pretty much a bump till a diesel guru can come by and help But the no throttle reponce could be your accelerator pedal position sensor. Do you have an gauges ? Or a Scangauge?

 

I'm definitely no guru... but willing to ask some questions...

What's the state of the truck right now? I'm a little cornfused.

What led you to believe the harness is bad?

 

After waiting about 2 hours I went back to Sears to start the truck. It started fine and ran normal. So the truck is running , but the last two days after some running around town and multiple stops, the truck will not start and once yesterday at highway speeds it would stumble. After a couple of hours rest it starts and runs fine.

I will need to pull the harness to make sure it is the harness, but from all I've read, it could be that. Another likely culprit is the HPOP. Replacing the STC connector, dummy plugs and stanpipe is the suggestion that I'm seeing for people with similar conditions. But it may be a number of other things or combinations of things. For sure I need to change the fuel filters as I've exceeded the interval suggested.

I wonder if switching to the lighter synthetic could have broken some stuff up and is clogging the system somehow, as most if these problems happened a week or so after making the switch. Truck has right at 150k miles.

I do not have a scanner for codes. AutoZone said if the check engine light is not on their scanner would not give any codes. I checked the voltage of both batteries, but not under load. They both read 12.8 volts with the truck turned off. I did not pull the batteries to have them individually load tested. Fluid levels in the batteries were fine.

I'm considering getting the Scangauge II, but want to do some more research to know if it will be if much value to me.

 

In a nutshell - ScanGauge is worth it - you won't find many that would disagree with that...

On your synthetic theory - I had a similar situation. Decided to change to syn to help with cold, rough running. Within 1,000 miles my HPOP died and truck just quit. Coincidence? I don't think so. Still have the synthetic with a new HPOP. My HPO pressure maxed at 2,000 PSI before the pump failed (I thought that was normal). Now it hits 4,000 on some WOT runs.

You need a way to monitor your HPO PSI and the Scangauge is the answer.

Next time your truck won't start - try disconnecting the ICP sensor and try again. If it starts, there you go.

Intermittent problems are a bear to troubleshoot (took me a week to track down a bad circuit breaker on an F-16 one time because it only happened in flight - we spent a lot of extra money on JP4 that week). There is a great no start thread in the tech folder. In there, somewhere is your issue.

 

Forgot to mention, your 04 doesn't have an STC fitting. 05's and up - and 05 was the worst year for failing before they redesigned it.

 

Thanks. I'm currently looking at the threads on the Scanguage and I'm definitely in. I'll check Autozone tomorrow and if they don't have one instock I'll order on Amazon.

I've read about disconnecting the ICP sensor, but I don't know where it is located. Any help would be appreciated. I think I saw a picture posted with it's location when I was trouble shooting a bad EGR valve about two years ago, but I don't remember where it was.

 

He could have issues with the stand pipes and dummy plugs. Lighter oil causing hot no starts due to a leak in the HPO system.

 

It's on the front of the passenger valve cover (if your truck is a late build 04). If it has the 03 motor it is directly under the turbo and not easily unplugged. In the case of an 04 motor, you'll want to check the connector pigtail for excessive oil when you look at it. A Google search on ICP sensor will quickly take you to some pics and the location.

Unreal04 is right. Your hunch about the HPO system being suspect is a good one and getting a Scangauge will go a long ways towards diagnosis. Autozone has 'em in stock.

 

possible HPOP leak. could also be ipr screen. if during the times where there was no acceleration after pedal had been depressed, and there was white smoke puffing out the exhaust when tat occurred, then it might be an egr cooler or oil cooler. in tat case, replace both egr cooler and oil cooler.

i'll chime in again when i tink of something else. i'm a stickler for covering all the bases. i learnt tat and more from my previous and current marriage. lol

 

1). There can be codes stored if there isn't a CEL--Autozone is WRONG.
2). Pull and clean the EGR valve.
3). Possible IPR issue causing the no start but need something to monitor that PID
4). Possible FICM issue causing your injector issues/stumble/no start--see tech folder for testing procedure--easily accomplished with a DVOM.

FWIW--a SGII is a great, economical monitoring tool that can give you tons and tons of information and for <$160 is usually cheaper than a trip to the dealership.

 

I have experienced some Autozones being unwilling to loan out their code reader unless a CEL is on. Don't know why though.

 

Ok, I bought a Scanguage II. There are no codes and no pending codes. I'm looking at the X-Guage features and going to learn how to input them. Any suggestions on what I need to look at would be apreciated. I know FICM volts, but other than that I'm not sure I'll know everything else I need to check. I'm about to do the search, but I might overlook something that is potential clue to the problem.

 

ICP pressure for sure - engine needs 800 PSI to crank, 500 PSI to run
IPR valve % - Ford tech says 24 - 30% at idle (mine is 22% at idle)
EOT - oil temp should stay pretty close to ECT - max 15 degree seperation on an unloaded truck (ECT is pre-entered as fWT -coolant temp)

You'll get a lot of good feedback on this from several guys. This thread is a good place to start -> https://www.ford-trucks.com/forums/1...-settings.html

 

I programed the ICP, IPR and FICM main volts. All three of them look normal. I will look at some other guages tomorrow. Thanks