First post here, be gentle! Heck, I'm desperate, be as rough as you want. I have a 2009 Escape, 2.5l engine and manual 5 speed transmission, 205,000 miles. It has has an intermittent miss that has been getting gradually worse over the past 3 months or so. I've been seriously futzing with it for the past 2 months, so far no luck. Definitely worse when it's cold. Not noticeable at all in gears 1-3 (even when cold), noticeable in 4th, mostly between ~2000-2500 RPM, and pretty bad when cold in 5th in the same RPM range, still noticeable when warm. No service engine light until today (#1 misfire). If I let the vehicle idle for 10 minutes or so, the miss is much less noticeable. Replaced the plugs, absolutely no difference. Bought one COP and cycled through all cylinders, no difference. Finally broke down and took it to the Ford dealership where I bought it new and had them do a power balance test, which isolated it to cylinder #1. Swapped the #1 and #2 injectors and took it back to Ford, still showing cylinder #1. Did a compression test, #1 and #2 both around 165lbs, #3 and #4 both around 185lbs. I'm a electrical engineer, so I spent some quality time with an oscilloscope to compare the drive waveforms of the #1 and #2 cylinder COP and injector...both COP and injector drive waveforms look identical when comparing to #2 cyl. Tried heating the PCM, made no difference (engine was cold, PCM was hot). Frustrated much? Yep!
So it finally DID throw a code today, cylinder 1 misfire. I'm thinking I can almost hear a miss at idle now. And listening to the valvetrain at idle, there is unmistakably more valve noise coming from the #1 intake area than the other cylinders, but not terrible.

Any ideas or suggestions?

Thanks!
Ustabe

 

Ustabe sane and now own a Ford...
Off the wall, I'd disconnect & plug the EGR system, drive, note presence or lack of misfire. Sometimes the EGR flow can make marginal cylinder(s) misfire of there is carbon-ed up ports where it flows into the intake.
Did you replace the boots on the COPs? If the boot gets oiled, it loses some dielectric properties(no, I am probably using the wrong terms, but whatever) and can cause the spark to jump the the wall of the well the plug is housed in. If the cam covers leak oil into the well, well, you'll need new boots in addition to new cam cover gaskets(O-rings in cross section).
Last thought is valve lift being different due to cam lobe wear. That would require removal of the cam cover. Second to last thought is to do a CO2 sniff of the radiator at the degas bottle. If a head gasquet is starting to take a vaycay, you might have combustion gas leak into the coolant which would show on a detector.
tom

 

Ustabe sane...that's about right Tom! Thanks for your comments and insight. COP boots are all clean, no cam/valve cover oil leaks at all. EGR doesn't seem to be the issue either, at least it got no better with EGR disconnected/plugged.

I went ahead and pulled the cam cover and took a look at the cam lobes. Nothing noticeable. Intake lobes are all within ~5/1000's, no noticeable or odd wear on the buckets. Two things I DID notice though: while all the exhaust cam lobes have obviously been riding the buckets all the way around, none of the intake lobes were making contact 360 degrees. Since it's ALL the intake lobes, I don't think this is an issue. The other thing I noticed was the timing chain definitely droops about 1/4-3/8" between cams when I rock back and forth (and all the slop ends up between the cams). Here again, I can't imagine how this would result in a #1 misfire.

Pretty much at a loss at this point. Any other ideas/suggestions?

Ustabe

 

Just re-read. Intermittent and more noticeable when cold misfire.

Make me want to take a look at intake manifold and/or gaskets. A cold O-ring will not conform to the groove/channel that locates it, well, to the top/bottom as it gets hardened by heat cycles. They start out as a slightly compressed O in cross section, and eventually get hardened into an O with the top and bottom flattened against the manifold/head surfaces or whatever they seal. When cooled, there may be a slight gap at the top and or bottom, causing a slight air leak which is unknown to the computer.
The fact that you notice, I think, misfire when accelrating or 'loading' the engine in 4th gear, where spark is hardest to fire, especially if the mix is slightly lean, points me to checking those and also taking a look at the spark plug gap. If you do, also take a look at the electrodes. A good, square, sharp electrode will gather electrons easier so they can all jump together. If crowded onto a rounded electrode, they shy away from each other, and cannot get the gang all together to jump as one.. Obviously paraphrased.
Any way, make sure the center electrode has squared corners, and the side electrode is not 'hollowed out', and also presents a flat surface to jump to. They fire better.
What is being described is almost a definition of 'lean misfire under load'... more or less.
tom

 

I'm just going to throw in that I had a misfire and changed the 3 rear COP's and all plugs while I was in there. 2000 miles later I had it come back.
Ended up being a plug that went bad. Complete open internally until it got warm, then it sorta worked.

...just sayin'.

 

Thanks for the input Tom and Got2bjoester.

I probably should have mentioned that early-on with this issue, prior to even realizing it was a misfire, I figured, what the heck, it has over 200k, I may as well change the PCV valve. So of course at that point it got all new intake manifold gaskets. Didn't make a bit of difference.

Based on Got2's input, I went ahead and installed another new set of Motorcaft plugs. Nada.

Of course it is entirely possible that in the process of diagnosing, troubleshooting, and replacing parts, I've done harm. But, other than getting gradually worse, the symptom has remained virtually the same throughout.

I'm confident that if I took it to Ford (or another reputable mechanic) at this point, they would do exactly what I've already done (other than the PCV valve, of course). Might not be all bad though, just costly...

Thanks again guys. It's gonna get fixed, and when it is, I'll pass along the resolution. Sure is a painful process though...

Ustabe

 

Have you used a scan tool to watch what is going on while you are experiencing the misfire?
If you try to accelerate in 4th or 5th, without downshifting, does it buck a bit? If so, would that match the condition you describe? From what I know, or think, that is misfire when the plugs don't want to jump across a high pressure condition, more or less.
tom