BubbaGee

Hello all. I have a 2007 Ford F150 SuperCrew with 5.4L V8 (with 126,000 miles) and been fighting an on going issue. I'm getting misfires on cylinder 2 and 4 after the engine warms up. When I check for diagnostic codes I'm seeing nothing, but when I read real time data I'm seeing misfires on 2 and 4. Doing a little testing, I noticed the misfire is more prevalent if running with O/D on than with it off. I don't get the misfires when the engine is cold either.

What has been done:
Plugs changed at 85,000 miles.
Fuel Pump Control module replaced around 90,000 miles.
Running semi-synthetic oil.
Tried different brands of gas.
Tried fuel additives.

Conditions that cause misfires:
Warm engine.
O/D is on.
Speed range of 40 to 60 mph (low RPMs)
Slowly pressing on accelerator, trying to increase speed.

Without any codes being thrown I'm at a loss of what should be looked at next.

BubbaGee

Martian

Swap the coils on cylinders 2 and 4 with two other cylinders and see if the problem moves.

SCORGE

Ignition coils ever been changed?

BubbaGee

Scorge, I thought they were replaced but after looking at them I'm starting to think they may not have been replaced. I'm thinking that if I'm going to go to the trouble of replacing the coils I might as well replace the plugs too since I'm sure the misfires have caused the plugs to begin to foul as well.

Thanks,
BubbaGee

Martian

Depends on how long it's been misfiring.

Jetdriver480

Replace ALL of your coils and while you are there you might as well put new plugs in as a bad coil can ruin your plug.

I guarantee you this is the problem.... it's very normal, almost a guaranteed event on these crappy engines.

I bought my coils on Amazon for what it's worth and saved a ton of money.

techrep

iTrader: (1)

What brand plugs were installed at 85K miles ? were the springs and boots replaced then ? was dielectric grease used properly ? a quick COP swap like Martin mentioned will help troubleshoot.. does the CEL flash while driving ?

BubbaGee

Martian, the 4 cylinder has been misfiring for at least six months. The last two months it began to get worse, to the point it happens regularly now.

Thanks,
BubbaGee

Martian

Trucks misfire all the time. Like, every time they run, there will be a few misfires. The question is how bad is it.

Dirttracker18

lol
Dealing with something like this on a truck I just picked up. Similar issues with low RPM, high load miss.

Showing an intermittent misfire on 5 and 3. I went to swap the coil on 5 with 1 and noted no dielectric grease, even the the PO claims a recent plug change. I greased both coils before the swap and now I cannot reproduce the problems.

I hope luck is with me and this resolved the problem. Sometimes its the little things.