04 Mecrury Monterey 4.2l Issues

[Tractor Dan]

Ok. This thing is acting up yet again. This engine has been a pain the last year or so for only 118,000 miles on it. Anyways here is the details.

It has a rough idle. When under load, say trying to accelerate from a dead stop it stumbles and bucks. Had it out Saturday and it back fired i believe a couple times. I heard a couple pops in the engine area or right underneath the front seat area. I pulled the air filter and it's got a little dirt but could see daylight no problem through it holding it in the air. Checked the butterfly on the throttle and i can tell it's running rich. It kicked the check engine light on and was flashing it Saturday. I got the codes pulled and it was these.

Cylinder 1 misfire,Cylinder 1 misfire on start up.

Plugs and wires were done last July. Replaced with motorcraft plugs for sure. Not sure on wires. Can't recall if i bought autozone or motorcraft off of rock auto. We also pulled the coil and tested it when doing the plugs and it tested good. (Learned my lesson on my Ranger, replaced plugs and wires when i got it and sure enough coil was bad too).

So any ideas what could be causing the misfire issue? We do routine maintenance on it. It's not every say 3,000 miles it gets an oil change but never goes over 4. I do have a fuel filter for it i just haven't been up to replacing it since surgery. I don't think the fuel filter is the culprit but figure it can't hurt to replace. So any thoughtsx or insight are appreciated. I have been reading and i'm thinking it's the cam snychro acting up. Seems the f150 had this issue with that engine.

2004 Mercury Monterey
4.2L
118,000 or a hair more miles on it

 

[RonD]

It has a Mass Air Flow(MAF) sensor, these can cause bogging and missing when they get dirty.
This is the Ranger version which will be similar:
http://www.therangerstation.com/tech_library/CleanMAF.html

Run a can of Seafoam in the tank to clean up injectors.

The O2 sensors are heated make sure fuse is good.
O2 sensors are also like spark plugs in that they do wear out.
Many think 60k-80k is their limit, my '94 4.0l are still working fine at 300k, so........
An O2 sensor going bad doesn't always throw a code, engine just runs rich or lean thinking it is running correctly because O2 sensor is off.

Does the engine temp run at normal or below normal, people often think running a "cooler" t-stat is better, it isn't.
I think yours should be a 192deg t-stat, an engine should warm up to "normal" in 5 minutes, if it takes longer then you probably have the wrong t-stat.

 

[Tractor Dan]

I'll give the sea foam a try if I don't have any I know I have Lucas floating around the basement. Engine seems to run at a normal temp. Usually within 5 minutes like you said it's about middle of the temp gauge where it should be. I guess I'll give that MAF sensor a clean it can't hurt. Gotta figure this out it has to drive 3 hours to Cleveland in a week.

 

[Tractor Dan]

Just wanted to update this for anyone who has a similar issue. Finally solved the problem. The coil pack for the ignition was bad. So had my mechanic replace that and the plugs. Would have done it myself if i were in better shape but that's life i suppose.

 

[RonD]

Thanks for the update