My father in law has a 2002 F-150 2wd, 4.2L, 5-speed, SB, with about 76K miles. The truck runs rough & seems to miss at idle, & especially when first starting out from a stop. It also usually cranks longer & takes longer to start than most fuel injected vehicles. He said it runs fine about 70 mph on the highway though. The truck used to run rough occasionaly and have a hard time starting, but now it does it everytime. It throws the SES light, which gives codes for it missing on a couple cylinders (I think # 4 & 6). As time has gone on, the problem is getting much worse. We have replaced everything we could possibly think of, and little to no change has come of all this time and $. PLEASE HELP! We are Soooooo Sick of this problem!!!

I read another post that suggested checking or cleaning the IMRC (Intake Manifold Runner Control) switch. I've never heard of these before and would like to know if anyone else had this problem and what fixed it. Also, anyways to test the IMRC, or how much it costs. I'm totally open to suggestions or what others have found.

Here's what's been done:

• Spark Plugs (Bosch double tip platinums)
• Spark Plug Wires (AutoZone Lifetime Warrantied)
• Fuel Filter (Purolator)
• Coil Pack (AutoZone)
• EGR Valve (AutoZone)

 

Is the engine making a ticking noise that seems to come from the valve cover? I have heard of a few of them (including mine) breaking a valve spring. It does just what you describe and amazingly runs pretty good at highway speeds. I think maybe the pressures inside the engine help hold the offending valve shut at higher engine speeds.

 

Actually, yes it does! He also reported the gas mileage went up a bit too.

 

It might not be the problem in your case, but over the last 6 years I have been here, a few guys have had problems with plug wires. Even new plug wires have caused problems as you describe.
I see you have changed the plugs wires and plugs. Was that a recent attempt to solve the problem?
Some have found the 4.2 (in some cases) to be pickey about plugs and wires. And, some have found the Bosch plugs to be one of the worst offenders.
Perhaps the problem was degraded plug wires and/or plugs. For the record, 75,000 miles on an '03 is right about the time the factory wires will start crapping out.
If nothing else works, try going with Motorcraft wires and change the plugs.
You can use regular 'el cheapo copper plugs. They work great, just won't last 75,000 miles.

I might be wrong, but I do not suspect IMRC problems with what you describe. There are codes to indicate IMRC stuck open or closed, and you don't mention seeing those coeds.

Keep us posted!

here's a thread on plugs and wires: https://www.ford-trucks.com/forums/s...ght=spark+plug

Thanks.

 

Cool, thanks Brian A!

Yes, the problem was before the plugs and thus we changed them as a 1st attempt to solve the hard starting, occasional engine code problem. I've never had good experiences nor heard good things about Bosch plugs in Fords, and always run Motorcraft or Autolites myself. Maybe we'll swap out for Motorcraft wieres and Autolite plugs before we investigate the broken valve spring.

 

Cam position sensor maybe? Probably not a cracked coil pack if his mileage went up.

 

BUMP

did you ever get the problem resolved? If so, what was the cause?

Thanks!

 

He replaced the plugs with either Autolite or Motorcraft and its much better now. He's going to get factory plug wires and hopefully that will completely solve it. I haven't riden in it yet, but when we get it totally fixed I'll provide a more detailed update.

 

Well, to bring an old topic back up, the truck has never fixed itself, but hasn't gotten worse either, until it stalled today and he couldn't get it restarted. They called AAA and then tried again. It finally started when the tow truck driver was only 10 minutes away (don't that figure)! It's hard to believe this post is about 3 years old, but he would try a few things with no luck and then just keep driving it. Other than the truck most times taking about 15-30 seconds of cranking (once in a while it fires up just like it should) and the truck throwing codes it has run just fine.

I think I've finally got him convinced to get some Motorcraft plug wires. They're just so expensive especially considering the ones from AutoZone have a Lifetime warranty. Since the first post we've also done-
*fuel pump
*changed the plug wires again
*changed the EGR sensor (that's what he said, not sure if there is an EGR sensor or he was thinking of something else)
*Cleaned the IAC (Idle Air Control) & Mass Air sensor
*New air filter
*Cleaned the throttle plate

Just wondering if anyone else may've been down this road. The codes he keeps getting are P0172 & P0175. Today my scanner said it had 6 codes, which were the 2 just mentioed and then it had P0000 in there for the remaining 4.

 

If anyone's got any experience with these 4.2L's running rough, starting hard, etc please let me know. We're running out of things to try.

 

Check this thread.....

https://www.ford-trucks.com/forums/8...-too-lean.html

 

Well he finally took the truck to one of his other son-in-laws uncle's who got laid off and opened his own mechanic shop. They hooked a gauge up to read the fuel pressure and saw it bleed off immediately. He then determined that 2 fuel injectors were stuck open. $100 or so later and it runs like a dream & starts instantly!

I'm SOOOOO glad this B is finally fixed!!!