Check for a water leak back there. That's the rear driver's side plug.

 

My 2004 5.4L 75k will backfire if I am driving at a steady speed and jump on it and when I tip-in on the throttle I will feel it stumble at time. If I jump on it off the line no backfire and it takes off OK.
My next step is to change the plugs. Understand the 2004s are on the third recommended plug type.

To my F150 backfiring

The Ford dealers have a portable LapTop Tool (IDS I think) that they can observe the engine balance as it relates to each cylinder firing. This help them diagnose which cylinder is acting up. Same tool also has simple injector test that can identify problem injectors.

 

Mine does the same thing and with only 38k on it, I put it in new fuel injectors and that didn't help and I have no codes stored either, any one have any advice.

 

Well, after getting the 1 and 8 coils replaced, I picked up my truck and half way home it started to sputter again and the CEL came on. Back to the dealer. This time there was low compression in 2 and 7. The used car manager decided to replace all of the coils and plugs. 3 days later, (after several bkoke off plugs) I got my truck back. I have been flooring all day with no problems. Hopefully my problems are solved. At least it was all free and I got a new clutch package. Now I can install the edge evo I bought several weeks ago.

 

I had the same problem with my '07 with 110k miles. I replaced the plugs this weekend and the shudder/hesitation are gone. I had ordered new coils, but decided to put the old ones back on and try it first. Apparently my coils are fine cuz the problem is gone.

A buddy had told me it was bad gas. I first tried higher octane fuel and it seemed to get better, but still hesitated some. I figured it was ignition related and the higher octane fuel just masked the real problem. I was right.

 

AGREED had the same problem with brand new cats and new coils it was a injecter test with mulitmeter to make sure

 

This sounds like what my 05 is doing. I can't tell if it is just having a problem shifting into second and sometimes first or if its the engine losing power or cutting out. I can punch it at 60 and as it shifts down then the truck will hesitate a bit and then surge a time or two before it clears out. I've had it do it at say 20-25mph also after it drops down into 1st. It doesn't seem to do it from a stop or if I let into it slowly. It seems to only happen after a downshift. After reading this I will be checking my plugs.

I can't believe that dealership thought it was the differential clutches and the Hondaship fell for that. Do they even know what those are? We are talking about the differential clutches in the rear-end right? They only come into play when you're off-road or breaking traction. I'd refuse to let those idiots work on my truck if they were that clueless. Good thing it was under warranty.

 

How long since the fuel filter was changed?

 

I agree. But since it was free, I didn't have a problem with it. Now that the warranty has expired I won't be taking back to either one of those dealerships.

 

I just left my truck at the dealership today for what sounds alot like your problem. I also suspected the plugs, or coils. I have had to bring it back twice for plug problems since I had them changed at 60k. They charged $100 just to diagnose the problem, which They told me was that transmission fluid was a little low, and that it was leaking through the seal into the transfercase , overfilling the t. case. And this is what was causing the shuttering. I gave them the go ahead to replace the seal and flush the trans. that part of the repair was $800. Ive had a sick feeling about this since I left it.

 

Keep us up to date. Do you know if they used any diagnostic tools like a laptop interfaced to the engine to monitor engine accelerometers (complex balance test, often helpful not perfect). How low was a little low ... were you below the add mark on the dip stick.

Still have to get back to resolving my truck issues. Side tracked by three large home projects ...

 

Lol...I'm currently sitting in the waiting room of a Ford dealer 6 hours away from home with the same problem. Truck completely died when I got into the hills. Ran fine on the flat ground with my foot out of it. 2005 FX4 SCREW 5.4

 

They said that the fuel control module was corroded and was acting up when it got wet. Made it home though...

 

The module is basically sealed with one electrical connector. So did the connector loose it's seal and allow water in? The module is mounted on the underside on the frame.

 

FPDM corrosion on the 04+ is a known issue. It's mounted without standoffs and the backside of the case actually rots.