We have a 2002 F150 with the 4.6L (COP equipped) engine. We've replaced the plugs, wires, fuel filter. Checked the fuel pressure (within range), the injectors (all are firing) and the vacuum (17"-19"). Everything seems to check out but the engine is definitely missing. Not sure where to go from here. Is there any way to check the individual COP's for a failure there???? Any suggestions would be appreciated - not much hair left on the head.

 

Any number of things can make these engines miss. My Grand Marquis had a fuel oxygen sensor go bad, then it started missing at idle because it was running too rich. Even if the check engine light isn't on I'd check for codes before throwing any more parts at it.

 

Cleared all codes - drove - check engine light on. Current codes are "EGR Out of Range" and an O2 Sensor Code. We're hesitant to just change the EGR Valve because a visual check shows it's not that carboned up. The O2 code is the usual "false" code when the engine isn't running smooth. Maybe we should consider the EGR replace now. ???

 

Just curious, what wies did you change if it has COPS?

The common problem with these engines when they give an EGR code, it is usually a faulty DPFE sensor. Have you checked with the engine running and put vacuum to the egr valve? It should bog down if it is properly working. If not, then I would check the EGR ports in the intake. You will have to remove the TB to do so.

 

LxMan1 is right, if that DPFE is original, I will almost bet donuts to dollars that's your problem. The originals are made of pot metal aluminum and corroded shut ever so slowly causing a miss, but no code sometimes. The replacement is plastic.

 

Thanks LxMan1 and High_Horse. I meant to say "boots" not wires. We weren't aware of the problem with the DPFE. We'll give that a try and I'll post the results.

 

Let us know what you find out.

 

OK. We started by putting vacuum to the EGR valve. It bogged the engine down so we moved on and installed the DPFE sensor. No luck. We still have a miss. The curious thing is that under a load (like going up a hill) if you stand on the gas it will stutter then catch and accelerate (but only under heavy load). Fuel filter has been replaced and the fuel pressure is within limits. We can't really throw any more parts at this one. We're stumped. Still getting "EGR Out of Range" and "O2 Sensor" codes. The only thing left is the O2 sensor and the fuel pump, but I'm hesitant to spend anymore money on it. HELP!

 

Earlier you stated the O2 code was a false signal, why would you say this? Since the O2 measures exhaust fumes to regulate air/fuel mixture and the 'puter goes into a default mode with an O2 code. Thus when you need more fuel to air for the load, the 'puter won't provide it because its in default mode. Have you tried reclearing the codes again and how long does it take to get them back?

There is another possibility, and that's a failing coil pack. They won't show up on codes, but will cause stuttering at intermitent times. I've heard you can take Windex and individually spray each one to find the bad one, it will start missing. Coil packs are $50 from your local parts store if you need one, Ford charges $99. Its a cheap check, plus after that you'll have nice clean coil packs

 

Faulty coil pack was the magic answer. We performed the Windex test and found it on the 3rd try. Thanks High_Horse!

 

Glad it worked for ya ....

 

It's pretty easy to locate a bad COP with a scanner capable of retrieving Mode $06 data where misfire data is stored in the PCM. The PCM incorporates a misfire counter for each cylinder, and will show which cylinder is causing the problem.

A because of the way misfires are detected, a simple code reader may reveal nothing more than a pending P0300 multiple cylinder misfire code. Apart from the defective cylinder which contains a high misfire count, a couple of cylinders adjacent in the firing order make record a few random misfires as mere spillover from the problem one. So, you might have faults recorded in three cylinders, inducing the code reader to display a multiple cylinder misfire.

You have two basic options. Get a new coil and start swapping; or locate the defective coil with a scanner.

 

Problem is SB, is that if the coil is slightly failing, it won't register on the scan, eve a deep scan, especially if its intermittent. The scan will only pick up a hard miss, one of the areas that needs recalculated on the 'puter.

 

If the coil is only *slightly* failing, then it's unlikely that a driveabilty problem will be observed.

But in any other situation, you really have to do the scan/capture while the engine is being forced into a misfire situation. From my experience, compromised coils tend to be most vulnerable to misfire at about 35 mph when the throttle is being held in OD just below downshift. This scenario tends to provide a lot of useful diagnostic data in the $06 individual cylinder misfire counters.

Can you suggest a better way of doing this?

 

Unfortunately no, my experience is primarily from a total coil failure. The ol' #8 one that has been my suspect. But, I did have a partial failure awhile back, but I already knew which one it was. I was getting sluggish hesitation, especially on accellaration. I had my mechanic put a deep scan on it and it failed to register, but I was getting the symptoms of a failing coil, usually around the 1450rpm range or as you stated the 35 mph area. Since I knew which one it was, I replaced it straight out. That is where I came across the windex method, though I hadn't attempted myself, my mech. suggested it the next time.