2004 Excursion Diesel.
Had been running rough for a long time at 1500 to 2000 rpm
Was told probably #1 and #7 injector but it wasn't bad enough top replace it.
We are traveling and towing a 6500# Airstream.
Ended up in Florida and had a noise that sounded like a blown engine. Had one mechanic that said he thought it was #1 and #7 injector.
Turned out that the #8 exhaust rocker arm was bad.
I also replaced #1 and #7 injector.
The truck ran GREAT without the trailer. I thought everything was perfect and we left town.
Initially the truck was running great getting 14 mpg towing trailer which was a big improvement from the 11 mpg that I had been getting.
Less than 200 miles into the trip back to Fort Worth I see the mpg dropping to 7 or 8 mpg.
Crap I think to myself what now. It got so bad that I could get through an intersection. Pulled into a FORD dealership and was told #6 and #8 injector where bad. What's causing this I asked. No reason it just happens.
So I replace #6 and #8 injector and on the initial test ride it drives like a bat out of hell. Just awesome. However when I start to tow the trailer it still does about 11 mpg.
In the 1500 mile trip from Florida I lost about a gallon of coolant. I couldn't see any obvious leaks until I saw vapor coming out from under the coolant cap. I replaced coolant cap in Fort Worth and again the car is driving awesome. Incredible gas mileage. Probably better than I had ever seen.
Had somene tell me that if the coolant system isn't under pressure the cylinders could overheat and fry the injectors.
Never have I seen an increase in temp on the dash board. Even when I had a big coolant leak from the resevoir. The only reason I knew I had that leak was that the engine started running like crap and I pulled over.
This morning we started on our trip from Ft Worth to Amaraillo annd then onto Co and Seattle.
The car is running great. Getting almost 15 mpg towing the trailer.
Before we hit 100 miles it starts hesitating again, and the mpg drops.
I am totally stumped. I did pull over and replace the thermostat and I am flushing the coolant.
Tommorrow I am going to the dealer to get a diagnostic run. If someone tells me I have another injector out and "It just happens" I may go completely postal.
Anyone have any suggestions so you don't have to hear about me on the news?
Steve 817-729-3017 cell or email firstname.lastname@example.org