I have a 2000 Excursion with the 7.3, right now it just hit 107K. I've been having a hesitation, skipping at low rpm's for a while now. Usually it's at a slight incline, but not always, going about 45-50 mph around 1500-2000 rpm. If I'm holding it steady it will skip, jump, hesitate until I let off or press the pedal down harder. But the fun part is that it doesn't do it all the time. It does it much more when there is less fuel in the tank and when it is hot and humid. Then there are days when it doesn't do it at all. I've tried to throw it in cruise when it's acting up to see if it was the pedal, but it still does it.

We've taken the fuel tank down, checked to see if there was anything in the fuel, completely cleaned all the parts of the fuel system, changed the fuel filter, we keep up on oil changes. We've taken it to a diesel mechanic who told us it was #3 and #8 injector. He checked the fuel pressure when it was acting up and it was fine. So we had him change the easy injector. It still did it. So my husband replaced all the injectors for different (more hp) ones and it still does it. We tried taking the tune out, changed the ICP sensor, still does it.

I usually run it with a superchips tuner in it, it has a large exhaust, cold air intake, new tranny and now new injectors.

We did try to run the codes with the superchip tuner, but it's not pulling any. No check engine light or O/D flash, nothing. We have a tuner for our big trucks and are in the process of getting a plug to run the 7.3, but until then does anybody have any ideas?????

Thanks!!!

 

Welcome to FTE...Did you check the UVCH(Under valve cover harness) that plugs into each head at the valve covers?If one is slightly unplugged it will cause problems.
Did you check for frays or bare wires going to the 42 pin connector on top of the valve cover?
Have you changed the CPS lately?
While you had the tank down did you do the IN-Tank Mods?

 

Thanks for the welcome!! Wish it was under better circumstances!!

I'm pretty sure we took it in for the CPS (that was a recall right?). Do they go bad often? Should we change it again?

We didn't do the in tank mods, because I didn't know about them at the time. If we have to pull the tank again we will definitely do the mods.

Is that the 50 cent mod you are talking about? I've been after him to take off the valve covers so I can show him what to do. We haven't tried that yet. I'm going to look for frayed wires right after lunch. Wouldn't the UVCH make the check engine light go on?

My husband said when he was changing the injectors he checked over all the wires and they all looked good.

 

It was a recall.How long do you think it has been?Do you have a spare you could try in there and see if the truck runs better?
UVCH....Yes,the .50 mod.If one is cocked and not making a good connection all kinds of crazy stuff happens.
No codes on the SCtuner,have you tried to pull any codes with a different code reader.....but no CEL????
You hang tight,we will get this figurred out....more mechanics on the way.

 

Here's a pic of a drivers side connection. You can see the left side of the connector is further out than the right. #2 ohmed completely open and #4 was out of specs. The symptoms were very close to your description. Here's a pic of the same truck with a chafed wire at the 42 pin connector. The CPS is an easy swap if you have or can get one, so I'd try that first. Definitely do the intank mods when you get the opportunity. Well worth the effort IMO.

Edit: Sorry for the cruddy pics, kinda hard to see.

 

Probably a couple years since we did the CPS. We have a spare 7.3 that we use for parts I could look to see if one is on there to try.

We have an Eaton scanner for our Peterbilt's. Not sure if it will work even if we had the right cable. I'm looking into that. We have a call in to our friend that has a Snap On code reader to try his again, last time it just pulled injector 3 & 8 which I hear is common. Never pulled a CEL ever.

My husband is under the hood right now taking a look at the 42 point harness, so far without taking it off it looks ok, but he's bringing it to the garage now. I'll see about pulling the valve cover to check the UVCH.

Thanks for your help. It's so frustrating all this trial and error.

 

Thanks Izzy! I know exactly what to look for once he get the valve covers off. I can only hope that it is something so easy. I'm sure with our luck it will be a broken wire somewhere in the harness. My husband said the harness looks good so far.

 

you can ohm the injectors without pulling the valve covers. The order of the connector is
GGIICIIGG
G=glow
I=Injector
C=Common
Check between I and C on all 4 and see what you get. Should be less than 5.0

Edit: Oops, I meant all 8, 4 per side obviously!

 

I'm definitely writing this one down so my husband will know what I'm talking about. Headed down to the garage. Will let you know what we come up with.

Thanks!

 

Here's some pics compliments of Chris (F350-6) for the quarter shim. I personally couldn't put quarters in my motor though many have with no problems whatsoever. I used homemade plastic shims as you can kinda see in the blurry last pic.

 

Should have mentioned, might as well ohm the glow plugs while your there. Ohm between G and battery ground. Should be between 0.1 and 2.0

 

Ok, before we can ohm anything my dad has to help so we will have to wait for the weekend for that. The ohm reader my husband has is really old and he's not sure how to use it, but my dad can figure anything out!!

We cleaned out some back pressure exhaust thingy, put a clean air filter on, and changed the CPS now we are going to test drive it. Since it's a beautiful day here with no humidity at all and I have around 1/2 a tank of fuel, it probably wouldn't act up anyway, but we'll give it a shot!

I'll keep you informed.

Thanks again!

 

It did act up slightly on our test drive. We took it to our friends house and he scanned it. It came up with P0284, which is Injector #8. We got this code before so I'm not sure if it's real since we put all new injectors in and that didn't help. Maybe it's something to do with a wire for #8? We are going to pull the valve cover on the drivers side and see what's up in there.

 

Taking the valve cover off showed the UVCH drivers side connection looking EXACTLY like your picture up above, Izzy!!! He is in the process of putting a quarter in there now. I hope that is the problem. We'll drive it around for a while now and see what happens.

Fingers crossed now for sure!!!

 

so enough suspense!!!!

did you get er fixed?