2015 - Engine cuts out going up hill with a load or pulling a trailer

[Joe Zanghi]

I have a 2015 Expedition, 140,000 miles. Recently the engine has started cutting out occasionally driving up hill while loaded or while pulling a trailer. I don't know if cutting out is even the right word for it. It's like it is running out of gas momentarily but the engine never completely dies. Here is what I have ruled out:

The engine is not throwing any codes
The air filter (K&N Cold Air Intake) is clean
The spark plugs were replaced about 40,000 miles ago
I've been told that there is no fuel filter to clog other than a screen on the outlet of the tank
I was nowhere near running out of fuel any time this happened.

I don't know if it is related, but my driver's side turbo has been replaced three times (twice under the extended warranty and once out of pocket). Nobody has ever been able to figure out why turbos seem to die so quickly, but I don't think it's my driving. I'm a fairly conservative driver - I rarely drive above the speed limit and almost never drive over 65 while towing.

The Expy is going into a trusted mechanic tomorrow, but he isn't sure if he can locate the issue. He said that if there was a fuel problem, he would expect it to be throwing a code. Does anyone have any suggestions of where he should look?

 

[07navi]

I would change the plugs before going any farther and get rid if that K & N setup.

 

[Boostedbus]

I’ve had a coil pack on my 5.4 van start to give out under hard load conditions like you described. It would misfire hard under load but wouldn’t throw a CEL. So finally instead of backing off the gas when this happened I put the hammer down and let it struggle until it finally threw the code I needed to isolate the misfire. In my case it was coil pack #5. It could also be plugs like 07 Navi said.

 

[Joe Zanghi]

I would change the plugs before going any farther and get rid if that K & N setup.

I've been wondering about the plugs too. For the cost, I might just have him change them out to see if that helps. What are your reasons for getting rid of the K&N setup? I've always thought that less restriction was better, but I'm willing to listen to other ideas. I actually saved the OEM parts, so it wouldn't be that difficult of a change out.

 

[Joe Zanghi]

I’ve had a coil pack on my 5.4 van start to give out under hard load conditions like you described. It would misfire hard under load but wouldn’t throw a CEL. So finally instead of backing off the gas when this happened I put the hammer down and let it struggle until it finally threw the code I needed to isolate the misfire. In my case it was coil pack #5. It could also be plugs like 07 Navi said.

Interesting - it never occurred to me to hammer down to force it to throw a code! I'll give that a try if the problem persists after getting the truck back from the shop. Thanks for the idea!

 

[Hamfisted]

Do you have ForScan on a laptop ? You can monitor actual fuel rail pressure vs. fuel pressure desired and see if maybe your high pressure pump is weak and might need to be replaced. But yes, the only fuel filter in the system is the little intake screen on the inlet side of the low pressure pump in the fuel tank.

 

[Motorcity muscle]

Has the mas airflow sensor been cleaned, with a k/n the oil can get on sensor. Cheap and easy to try cleaning it.

 

[07navi]

I've been wondering about the plugs too. For the cost, I might just have him change them out to see if that helps. What are your reasons for getting rid of the K&N setup? I've always thought that less restriction was better, but I'm willing to listen to other ideas. I actually saved the OEM parts, so it wouldn't be that difficult of a change out.

It's just that I don't believe in them. The Ford trucks already have a cold air intake and are engineered for the stock setup. They have more than enough air intake up to at least top RPM. The engineers aren't going to shortchange their own induction system. As for the plugs; the plugs can have a number of things go wrong with them including the boots. I change mine in about 30k anyway and like you said, not that hard to change.

 

[The Chairman]

Has the mas airflow sensor been cleaned, with a k/n the oil can get on sensor. Cheap and easy to try cleaning it.

The K&N set up works great. I have them on all 5 of my vehicles. That’s not the problem. However, if you over-oiled the filter and some of it got on that sensor, it can cause problems. So cleaning it is a good idea.
But like others said, sounds like an ignition problem.

 

[Brons2]

K&N's are for drag racing. They let too much dirt through for a daily driver, you will be able to see more silicon (dirt) on a used oil analysis using a K&N. Use a normal paper filter.