grumblegeek

I have a 2004 5.4L F150 Supercrew with 72,000 miles that I use as a weekend truck and about once/twice a month we'll tow our travel trailer for a weekend getaway. I've had the camper since 2010 but starting about a year ago I've had this issue.

I'll be driving along around 60 MPH with the camper and will hit an extended incline. To maintain speed I'll give it more gas but when the transmission drops to a lower gear and the engine revs up the CEL will start flashing, I'll lose power and AC, and I have to back off the gas. It will flash for a little while longer but usually goes off and everything is back to normal. Sometimes the CEL stays on and I've pulled the code P0305 "Lean Mixture on cylinder 5."

The truck runs great under normal conditions. When I tow our camper (always with overdrive off) it pulls fine and maintains speed. No issues as long as a hill is not too long.


So far I've:
-Replaced the fuel filter
-Had the dealership change out all spark plugs along with clean out the throttle body
-Replaced the cylinder 5 coil pack with a new motorcraft OEM replacement
-Replaced the cylinder 5 fuel injector with new motorcraft OEM replacement

And yet I still have this problem while towing. I'm about $1000 into this and worried about how much more it's going to take to resolve.

If I can maintain the throttle at the right spot where it doesn't drop down a gear it works fine however sometimes it forces me to slow down noticeably which sucks when I'm on a single lane with cars behind me.

Any ideas on what my issue could be? I'm out of ideas and googling is not bringing up anything new.

BadFish523

Turn overdrive off when towing

grumblegeek

I mistyped and edited my post. I always tow with overdrive off. Thanks.

BadFish523

Ahh that's better LOL. Do you have Torque App Reader for Android?

BadFish523

Torque could help you see real-time info and see if a different cylinder is giving you problems. #5 might not be the only one that's causing problems it was just the one that stuck long enough for a code. Can try replacing ALL coils. Many on here say the cheap ones from Amazon CAN work good just read the reviews. I'm guessing the dealer put Motorcraft plugs in?

grumblegeek

I'm not familiar with Torque App Reader. Would it be able to diagnose more than a simple code reader?

grumblegeek

Yes they used Motorcraft plugs. I'll look into the coils... just hate throwing money at this without being able to pin down the issue.

BadFish523

It can pull real time stats such as count each cylinders misfires, or temp at the head. You would be able to see if a different cylinder is missing but not enough to throw a code. The app is like $5 in the android store and a compatible reader is about $20. This is the one I've used for a long time with no issues. https://www.amazon.com/BAFX-Products...bluetooth+obd2


IMO way better than any basic code reader.

connorfx4

A flashing check engine light means a mis-fire.

Since you've already done spark plugs that shouldn't be your problem. Replace the boots and springs on the coils. You can buy all 8 for about $40 at your local auto parts store. Also super easy to do yourself.

screamineagle

A flashing CEL indicates a severe misfire. Won't take long for it to kill the converters due to raw unburnt fuel being dumped into them. I would check compression on cyl #5 before throwing anymore parts at it.