Missing under load 2nd Gen 5.4 Expedition

jjuscg · Feb 10, 2020

I have 106K miles on my Expedition and occasionally pull a 7,000 lb travel trailer. I frequently get a moderate engine miss under load, usually climbing a hill at 50 - 60MPH. Occasionally a check engine light, but not always. This happens more often with the trailer, but also occurs when not towing. No fault codes have registered over 20 or so incidents over the past 9 months. Shutting off the overdrive to increase the RPM helps avoid this. Plugs were changed at around 80,000 mi, but I don,t know about coils.
Since no fault codes are recorded, no one has been able to diagnose. I'm considering all new coils, wires, and plugs to deal with it.. Any other suggestions or diagnostic procedures I can try?
Thanks,
JJ

CountrySplatt · Feb 10, 2020

Hi JJ, what year is your Expedition? I have an 2004 Eddie Bauer with the 5.4L, and my max towing capacity is only 5000lbs. That aside, I would be checking air flow and potential vacuum leaks. If it isn't throwing any codes, that it isn't something that happens enough to trip the sensor. I have noticed on mine that the issue has to repeat more than once in given drive to throw a code.

jjuscg · Feb 10, 2020

Thanks, Splatt.
Sorry I didn't mention, it's a 2006.
Vacuum is a possibility I hadn't considered.. My heat control doors aren't working - are they vacuum controlled, or electrical servo? Also heater main coolant control hose vacuum line seems to be missing. I'll have to do some more investigation there.

According to what I read, with the towing package and 3.73 axle ratio it will tow 9,000lbs. It has been very capable on a number of long distance trips, but does loose steam on long steep mountains.

Ozzy · Feb 10, 2020

Following.

Oz-

thesavo · Feb 11, 2020

Spark plugs are a consumable just like brake pads. You're coming up on 30,000 miles since the last change. That's not long according to Ford.
The Service schedule for this truck is at 100,000 miles. The schedule for pulling a trailer, doesn't specify any different spark change intervals. However it does specify every 60,000 miles for severe driving. That includes excessive idling, long distance slow-speed driving, and delivery/livery.

My first thought would be to check fordtechmakuloco on youtube. He has done many great ford videos, especially on the 5.4l 3 valve engine.

Here's one on misses.

My next thought would be to atleast check the spark plugs for fouling or wear. Now, bearinmind that some of the rear plugs are hard to get at.

Are you getting a general miss or from a specific cylinder?

Another test would be to get a compression test done. However can be costly at some shops as it involves pulling each plug and checking with a Guage.

Sent from my SM-N975U using Tapatalk

GONS · Feb 23, 2022

Older thread- but wanted to highlight I had the exact issue towing a trailer, ended up being a partially clogged fuel filter.

Vincent Vega · Feb 23, 2022

GONS said:
Older thread- but wanted to highlight I had the exact issue towing a trailer, ended up being a partially clogged fuel filter.

@GONS I have been changing my fuel filter every 30,000 mi. Did you have issues on a filter with less than 30k on it? Thanks

GONS · Feb 24, 2022

No, the issue I has was loss of power while towing a trailer. I was shocked to find replacing the fuel filter was the fix. I now change the fuel filters on my Ford trucks proactively.

Missing under load 2nd Gen 5.4 Expedition

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