I have a 2004 Ford Freestar 4.2L engine with 79K miles. My wife has been complaining about an intermittent transmission stumbling. She had me take the car for a ride and a look over, but I could not find anything. I proceeded to take the car to the dealer for a fuel filter change because it was the original and overdue. I also added a bottle of Techron fuel injector cleaner. On my way home from the dealer, I felt a jerking for about 5 seconds while coasting at 40 with giving the car steady gas(no acceleration). The symptom my wife is feeling seems to be a miss without setting an error code. I want to change the spark plugs, wires and ignition coil because I am not too far away from the 100K change interval. My local mechanic said the coil would not be necessary but I want to do it because it will rule out the whole ignition system and the labor is basically the same. My mechanic likes to only use OEM parts from motorcraft, but I wanted to use the NGK Iridium because they will last longer. He said you sometimes run into a problem with using those type of plugs. Has anyone used the Laser Platinum or Laser Irridum plugs with the 4.2L engine and had problems? There are two different irridium that NGK lists so I want to know if it is the ix or the oem's. Also are their better wires that have the same length as OEM? Any input would be appreciated. Marc

 

Sounds like the same senario that I encountered on my 2004 4.2L at about 72,000 miles. The coil was the issue. I installed the NGK Iridium plugs and new OEM wires with no change in status. Then, I installed an Autozone coil a few days later. Now at 127,000+ miles, the ignition is still going strong with no intermittent miss. The iridium plugs put a less electrical strain on the ignition system and are easier to fire under compression.

I did have to replace my Cam Synchronizer last month at 126,660 miles due to the "Bird Chirping" and the occational idle stalling and tranny buck. If you have the "Bird Chirping" and the occational idle stalling and tranny buck, I would look at the cam synchronizer.

 

is it hard to replace the cam synchronizer when the cowl is off? And what is this bird chirping? I do get the slight buck but I believe that is a miss.

 

The cam synchronizer replaced the old-school distributor. It's a somewhat easy job. The "Bird Chirping" noise is a common symptom of a failing synchronizer (bearings going bad in the synchronizer). Another symptom is stalling in gear when idleing. The other symptom that I has for the cam synchronizer was an occational "HARD" buck.

If you have a slight buck (the occational miss) especially under load, I would suspect your coil. That was the senario I had with mine as I mentioned at about 72,000 miles.

The coil, wires and rear plugs are easily accessable after removing the upper and lower cowl. Don't forget to use dielectrical grease in the boot ends of the new wires. I also prefer the copper anti-sieze on the plug threads.

 

While driving at steady highway speed, my mother in law's Freestar engine will sometimes misfire/"cut out" (her words) then resume normally. Local mechanic could detect no stored codes. It's been a well maintained vehicle she's owned since new. Thinking the coil may be the issue?

 

A bad coil could be the issue. It's the easier to replace between a coil or cam synchronizer. If not already done, I would do the plugs, wires and coil (don't forget to use dielectrical grease on the boot ends). I had no codes for my bad coil or cam synchronizer issues. Just had the "That ain't right" symptoms.

 

mine did that about 120,000 miles I replace coil wires and plugs which helped but not cure the whole entire thing but when I swapped out the cam position sensor which is about a 10 minute fix it cure the problem so it could be a combination of any of those issues I think I fixed everything for about $150but I did all the labor myself

 

Thanks for the replies. Plugs are recent. Coil ordered...

 

It sounds to me like you had a loose battery connection or ground, and when you took it off and reinstalled it, it was then tightened correctly... Ford Engine Repair Huntington Beach

 

OK, put the MC coil in a few weeks ago. Then drove the car for about 35 minutes on the highway. At about the 25 minute mark while going up a slight grade at about 55 mph there was one "jerk" that felt like the transmission was about to downshift then changed its mind. Nothing else.

MIL called today and gave me the same (vague) description as before... feels like the engine is "cutting out" for 3-5 seconds, then resumes- like the engine was swtched off, then came back on. No noises of any kind. She says the man who does her car work told her the transmission is OK (I have no idea about his credentials). The car now has a recent spark plug change, fuel filter replacement, coil replacement, air filter replacement.

The "emissions light" comes on from time to time, but a mechanic at a Chevrolet shop told her that was not something that would cause a problem. The nearest Ford place is an hour drive away.

What now?