What else can cause a misfire?

[getsum111]

I really have to wonder what is going on with my car. I am getting a hesistation, still, from just off idle until the secondaries open up. Friday night, the CEL started flashing, indicating a misfire. I am going today to get it scanned, but here is my dilemma. No matter what I do, this keeps coming back.
I have tried 3 different sets of wires, 4 sets of new plugs, swapped out 3 coils, rebuilt the UIM/LIM three times, installed a set of MSDS (precats died due to misfiring earlier.), swapped in a borrowed Pro-Flow MAF, installed MIL eliminators, tested the CPS, CPK, IAC, ECT sensors, installed a new upper O2 sensor, swapped out a set of injectors, swapped in a different PCM, probably some more that I'm not remembering.
Each time, the hesitation returns. The car ran fine after the MSDS went in, except for an exhaust leak at the Y-pipe. This has since been fixed, but the hesitation gets a bit worse every day. I've had the car to Ford, twice. All they did was charge me $80 each time, and then tell me that they didn't know what it was. :help: Any suggestions? I will pull the spark plugs and post pics of them tonight. Thanks for any feedback.

 

[rollinstylee]

have you or Ford tested the fuel pump? I've had hesitation and stalling problems in another car at low rpm and it turned out that it was running on almost no fuel pressure.

 

[getsum111]

Ooops, forgot to add that. Yes, fuel pressure was tested at 45psi, IIRC. I also have a return system, so my pump shouldn't be prone to failure. I also removed and cleaned out the sock, reinstalled it. No improvement.

 

[Alquistador]

Miss firing

Miss firing

I was having the same problem. Turned out it was water in a connector on the passenger side on the engine. On top of the belts. Cleaned it out and put some electric grease it my car has been running 100% since them!!

Good luck

Alvise

 

[getsum111]

I'll try that tonight. Thanks.

 

[98SVTC]

I recall that some people had problems with plugs and plug wires in that certain make plug wires didn't like certain make spark plugs. I suppose you'd be alright if you're using Motorcraft plugs and wires but if you are mix and matching manufacturers, that might be causing your problem.
Karl

 

[getsum111]

Right now Taylor Thundervolts and Autolite APP764's. Lots of people running them. I have also tried Ford racing and Magnecor wires, same issues.

 

[98SVTC]

Right now Taylor Thundervolts and Autolite APP764's. Lots of people running them. I have also tried Ford racing and Magnecor wires, same issues.

Yeah, you know, I'd love to run "other than" original equipment wires, especially ones with a color other than stock grey to liven up the engine bay but too many people have problems with even the Ford racing ones. Goonz had a problem with Autolites and some type of non Motorcraft wire. You might check his posts.
Karl

 

[getsum111]

His trouble was with the Magnecors, his and mine starated acting up at the same time his did. But what I don't get is why does it run well for a bit, then get worse as I drive it more. But I have already run stockers, it has done same thing.:shrug:

 

[FavoriteMystaque]

Carbon tracking?

Carbon tracking?

I had carbon tracking on spark plug 2, looks like pencil lead marks on the insulator. Everything has to be clean inside the boot and the plugs themselves, and put a little silicone grease in the plug boots. to keep water out. Also make sure all connections are tight, I had trouble getting the plug wires (Motorcraft) snapped on to the plugs.