Hello all
I am fairly new to the 7.3 world. I bought a 2003 7.3 Excursion about 6 months ago as my kid hauler. It has been great so far. It is not my daily driver but gets driven 2-3 times a week.

a few days(Saturday) ago I started it up to let it idle for a few minutes before driving it and it started fine. After a few minutes it started idle strangely. It sounds like a muscle car with a big cam loping. It clears up when the throttle is pressed and runs fine while driving. When driving when I let off the throttle to slow down it lopes really hard while returning to idle. Yesterday (Thursday) I started it up and after 2-3 minutes of loping at idle it reved up randomly. It was idling and then reved up quickly for a second or two and returned to idle. it sounded like some one put the throttle to the floor and let off. I would guess based on the sound that it shot up to around 2500 rpms. Last night when i pulled into my neighborhood the check engine light came on. I have not had a chance to get the codes read yet.
I changed the oil and changed the fuel filter 3 weeks ago and that is the only thing that had been done recently. Also the batteries are getting weak but the alternator is charging properly as of 2 weeks ago.
is this a common problem on these trucks or should I start prepping for an expensive repair ahead?

I will update once I get a chance to have the code read.

 

Im predicting P1280; ICP sensor

Unplug it and see if there's oil in the connector

 

Thank you Wes

It will be a day or two before I can get to it. Is it safe to drive with the ICP unplugged or is this just to see how it reacts at idle? I am assuming that the presence of oil in the plug means it is bad is this correct?

 

You can drive it unplugged. Mileage may drop a little, i wouldn't tow or haul anything heavy working the motor hard tho. Hate to admit how long (months) I've driven unplugged before. Yes oil in the connector means that the epoxy seal in the sensor Is failing/failed and the sensor won't read correct anymore, it will progressively or suddenly get worse. Bucking, near stalling, high revving and shuddering will become nearly full time instead of occasional. Unplugged goes to a default value that the PCM assumes. It's noticeable unplugged on my ZF6, go to start from a stop and it stumbles a touch at first like a gasser with to little throttle.

So if you go unplugged, have oil in the plug, and the issue disappears its safe to assume the ICP is bad. Motorcraft only replacement! Other brands doubt play well with these motors.

Another free thing to check is your IPR, make sure the tinman nut on the rear is tight, if it gets loose it will cause issues. Also the fuel bowl heater can cause bucking and surging, sometimes it will blow the number 30 fuse under the dash, but sometimes it won't. You can unplug it forever to troubleshoot if ICP unplug or IPR nut doesn't work

 

I appreciate you taking the time to help guide me through this.
I am working a 24 hour shift today and will have the 4 little tyrants all day tomorrow so nothing will probably get done until Monday with the truck. Thankful I probably won’t need to drive it as it is our spare vehicle.
I will update with how things turn out or be back for more advice if all of those items listed check out.

have a good weekend and thank you again
Steve

 

I'll go back to the basics since I'm not sure how knowledgeable you are.

I'm guessing it's colder than normal where you live or you put 15w-40 in it when you did your oil change 3 weeks ago and it's cold. During the winter putting 5w-40 in it will eliminate romping. You may have other things going on also but this is half my guess.

It randomly reving up is the computers way to get the engine warm faster. Also known as high idle. Though a couple things you said don't go hand in hand with what I said it's possible.

 

First time I washed my engine some water got into the ICP connector it and did some crazy stuff, just mentioning in case you did a wash.

 

Hi John
Back to basics is good with me.


I did put 15-40 in when I did the oil change. Theme have been between 30 and 65 here. It was close to 60 the day the problem started.

The “romping” or “loping” was very pronounced it sounded like my dads old track cars that had huge cams in them. The kid of sound like the car could stall out at any second the pause between lopes was so long and violent when it came back. I am not sure if that fits the definition of romping or not. I drive diesel trucks at work but, they are bigger trucks and this is my first 7.3.

I am familiar with the high idle when it is cold out side but, this was not the high idle kicking in. This was definitely a rev up. It sounded like someone put the accelerator to the floor for a second or two. From the sound of it it was upwards of 2,500 RPMs. I actually came out from behind the truck to see if anyone was in the drivers seat.

the truck ran smoothly when the throttle was applied it didn’t hesitate or feel down on power at all. It was only at idle every time it was allowed to return to idle even when full warmed up.

I said was because Monday morning when I started it up everything sounded normal and the CEL was off. I stopped by Advance Auto to have them pull the code but, the scanner would not connect to the truck. I am guessing the fuse to the OBD2 port is blown. I will check that on Thursday along with the ICP sensor. Monday’s schedule got messed up for me when my wife couldn’t get out of bed to go to work because her back hurt to bad. Lesson learned for her you Once you hit forty you can’t do the stuff you did as a teenager without stretching first. No more handstand competition with the 4 year old for her.

88 E-350
I have not washed the engine and it was not raining either of the days it was acting up. Good pull on a random event that could have caused it. Sometime we forget about the odd situations when trying to troubleshoot.

thank you all for your input I will update as soon as I have a chance to check things out.