'03 4.0L V6, cylinder 5 misfire

[NotAFordGuy]

I've got a misfire code setting on cylinder 5. The engine runs rough until it warms up, then the misfire goes away and the engine runs smoothly again. It's a k-Flex '03 EXplorer EB 4.0L V6, 4x4 with about 178K on the odometer. Any help would be greatly needed and appreciated.

 

[Mustang Guy]

Have you pulled the #5 spark plug and see how it looks? Move it to another cylinder and see if the code follows. Always look for the easiest and most likely cause first.

 

[TechGuru]

Ya when was the last time you replaced the spark plugs?

You want MOTORCRAFT SP500.

$23.35 shipped from RockAuto with discount code.

Also since you have a FLEX, run a full tank or two of E85 to clean everything out.

 

[Tech By Trade]

Start easy, Assuming the plug is in decent shape and not worn out, look at the plug, see what it tells you. Lean, Injector, fuel pressure, Fuel filter ect. Fouled, go after the plug, wire, coil ect. Water or oil, you have bigger problems. In my experience it was close to the same symptom and it ended up being an injector.

 

[NotAFordGuy]

We replaced the plugs and wires around 40k ago. I can't remember what we put in, but I normally by factory OEM parts. I never buy the cheapest nor the most expensive.

I did pull the negative battery cable today for about a 1/2 an hour while doing the brakes on another vehicle. There's no Service Engine Light on and it's running and shifting smoothly, with no miss or jerky shifting. It only seems to run rough when it's cold, then the misfire goes away, but the code stays.

What do you guys make of this?

 

[NotAFordGuy]

Water or oil, you have bigger problems. In my experience it was close to the same symptom and it ended up being an injector.

I definitely do not have coolant in my oil or oil in my coolant. If your problem was a bad injector, did you just change one or all six? When I reset my computer, the problem completely goes away.

 

[Tech By Trade]

Just the bad one. That was a year and a half ago and no more problems with any others. Before you go flock shooting I would interrogate the plug. better than just throwing money away.

 

[NotAFordGuy]

Along with the code for the cylinder 5 misfire, there was also a code for a downstream Oxygen sensor at fault, so I changed it. It's the one right below the manifold on the driver's side. The battery was disconnected for about 8 hours while I changed the rear struts and the supposedly bad Oxygen sensor. I got everything back together and reattached my negative cable. I then took her for a ride for about 1/2 an hour. She ran smooth with no misfire or jerky shifting. That was Saturday, April 9th. Sunday, April 10th, I let it warm up for about 10 minutes in the driveway at camp before bringing it home. When I got in, the Service Engine light was back on. It ran a little rough and did the jerky shifting thing again, so the Oxygen sensor wasn't my problem. It's going for state inspection later today, and my mechanic is gonna plug it in and see what codes he gets. It only seems to do it when it's cold out, being 40 degrees or below. That's why the guy at Advance Auto thought it could indeed be a bad O2 sensor. Any thoughts?

 

[NotAFordGuy]

I cleaned the IACV and the MAF sensor. Before I undertook the task of replacing my #5 cylinder injector, I pulled the plug wire to that cylinder and found my spark plug to be loose enough that I could remove it with my fingers!! WOW! I returned the injector to AA, compared condition of my plug to a new one, nixed the idea of replacing just that plug. They are NGK Iridiums and they're supposed to be good for 100,000 miles. I came home, put everything back together and took her for a spin. The misfire is definitely gone, but it's still doing a little jerky shifting at times, so it's going to the dealer later for a PCM flash. Thanks for all the help, guys. Crisis is averted!

 

[NotAFordGuy]

Had it at the dealership this morning to get the PCM/TCM flashed. The shop boss came out after a little while and told me that my software was all ready the latest version and that my transmission was failing internally, thus causing the jerky shifting. I told him it all goes away after I reset the PCM. He said, "Yeah. It'll run fine until it relearns the bad solenoid or whatever you have going on in there."

SO, how does it run with no quirks for a few days after i do the reset? It runs and shifts like it's new for a couple days, then starts setting the same cylinder 5 misfire code, an Oxygen deprivety code, and an EGR code? Then the jerky shifting begins. My thoughts are swaying to possibly cleaning or replacing the EGR??? Has anyone had success with these issues being solved by replacing their EGR? Any help is greatly needed and appreciated and thank you in advance.

 

[Tech By Trade]

I would just randomly spend money on parts, throwing them at it in some type of flock shoot rather than interrogating the system to find out what is actually causing the issue.

 

[NotAFordGuy]

I would just randomly spend money on parts, throwing them at it in some type of flock shoot rather than interrogating the system to find out what is actually causing the issue.

It's been plugged in at AA, but of course, they can't recommend anything. The dealership wasn't much help. They want $135.00 just to plug it in and tell me what's wrong. I've been laid off and not drawing unemployment since December. I tried the interrogation method with the Ex, but she's not talking. What to do now? Waterboard torture test on the 4.0L v6? Maybe I should make it an offer it can't refuse? I came here looking for help and offering some when I can. Unfortunately, for the forum, I can't offer a whole lot of help with this vehicle, because, fortunately, for me, I haven't had to do that much to it. It's a great truck. At 180K on the clock and body still in outstanding condition even in western PA, it's hard to believe that it runs so good, then doesn't, then runs so good, then doesn't. Dealership said my software was up to date.

Yeah, I gotta start somewhere, so I'm starting with a new EGR valve. I'll report back tomorrow with the results.

 

[NotAFordGuy]

Replaced the EGR valve today. Cylinder 5 misfire code came back after 10 minutes of the engine running perfectly fine. I may try the injector next. At least I'll have a bunch of new stuff on it when I finally find what's causing the misfire.

 

[drdoom]

I would just randomly spend money on parts, throwing them at it in some type of flock shoot rather than interrogating the system to find out what is actually causing the issue.

Good one ^ lol

 

[meganmc]

Replaced the EGR valve today. Cylinder 5 misfire code came back after 10 minutes of the engine running perfectly fine. I may try the injector next. At least I'll have a bunch of new stuff on it when I finally find what's causing the misfire.

So what ever became of this???

 

[mountaineer2004]

So what ever became of this???

He hasn't been here for 6 years, so I doubt we'll ever know.

 

[410Fortune]

Injector I’ve got 5$$$ on it

The computer recognizes what cylinder is misfiring that quickly is almost always an injector, especially if the plug and wire check out

Sounds like the 02 sensor was doing its job reporting a rich or lean condition in the bank with the bad/stuck/plugged injector

 

[1sicbronconut]

Injector I’ve got 5$$$ on it

The computer recognizes what cylinder is misfiring that quickly is almost always an injector, especially if the plug and wire check out

Sounds like the 02 sensor was doing its job reporting a rich or lean condition in the bank with the bad/stuck/plugged injector

And if it's driven enough that cylinder will get "washed" and loose some compression as well adding to the problem!