New to forums, but this one is making my head hurt. Have a 2004 Ranger Edge with 3.0L. Truck has what appears to be a misfire from around 1500-2100 RPMs. I have recently replaced plugs and wires. Fuel Filter is relatively new. I have also replaced the Throttle Position sensor as well. I have checked the resistance on the fuel injectors as well and appear to check good. My truck has no EGR System on it as I have ran into this problem before in the past with EGR Systems. Cleaned out my Idle Air Control as this has given my problems with my mustangs in the past. My check engine light is not coming on either with this misfire. It is working as it comes on with the ignition. Looking for suggestions. I have an idea about coil packs but don't really want to waste money sampling replacing a bunch of electrical components.

 

I see this is an old thread but wonder if you found a solution. I have a similar misfire on a 2003 2.3L at small throttle openings and light engine loads only. Same engine speeds, 1500 to 2000 rpm or so. No CEL, no pending codes.

 

For my particular situation I ended up replacing the power pack for the spark plugsand that fixed my problem immediately. That was also followed by new plugs and wires as well.

Good luck.

 

Thanks for the reply and confirmation. I have replaced the coilpack, plugs, wires, etc. I need to keep looking.

 

what octane of fuel are you burning in your engine

if it is 87 octane , try running 2 or more tanks of 89 octane ( disconnect battery for 30 minutes )

this ensures that the computer loaded memory has been cleared .

if you have not replaced the spark plug wires with new 1`s then i suggest that you do

magnecor are a good OEM type replacement plug wire ( cheaper than dealership )

 

Thanks for the reply and suggestions. Yes, I am using 87 octane fuel, which has always been used since the truck was new. I will try a different grade and may add some dri-gas or equivalent as well. The engine roughness does not appear to be related to pre-ignition or detonation. Here's a list of what has been done so far:

-searched for vacuum leaks; replaced two hoses from IMRC solenoid to manifold and actuator
-removed intake manifold, checked for cracks or signs of leaks around manifold seals at head, none found.
-cleaned MAF, IAC and MAP sensors and throttle body.
-checked the intake manifold runner (flaps) for freedom of movement and cleaned them
-replaced plugs with Autolite double platinum
-replaced plug wires
-replaced coil pack
-replaced TPS as the original lost its spring tension although resistance values look fine with no dead spots in the POT.

Because this problem only occurs when the throttle is just cracked open at low engine speeds and with a very light engine load, I still suspect there may be a vacuum leak I haven't been able to find (anyone have more creative ways to trace vacuum leaks besides carb cleaner, propane, and cigar smoke?). Also, "misfire" may be the wrong term. Rather than a "miss" or "stumble" on one or two cylinders, the engine runs very rough within a narrow rpm window (1500-1900). The problem is not limited to a particular vehicle speed or gear.

 

double platinum plugs using stock motorcraft wires is your problem

those wires are highly resistive and the OEM replacement coil has a hard time firing 2 very resistive spark plugs
i recommend switching over to the motorcraft SP-412 copper spark plugs

also your year of engine is not compatible with any percentage of ethanol mixed in with the fuel

see if you can find bottles of ethanol neutralizer at your autozone or other parts store

 

Thanks for the reply. For clarification, this is the Duratec DOHC engine in a 2003 XLT. Are you citing specs for the old Lima engine?

 

no! ethanol tolerance based engines in vehicles were not introduced until halfway through 2005

the rubber fuel line that connects from the steel fuel line to the engine is not ethanol resistant

i would suspect that very small particles of rubber from inside of the rubber fuel line are clogging your fuel injectors.

if you wish to continue using 87 octane fuels with ethanol , i would recommend that you purchase from a ford dealership .

a new fuel line from a 2010 / 2011 ranger xl ( they came with the 2.3 litre duratec engines )

and those fuel lines are ethanol tolerant

 

Well, I certainly can't rule that out without removing and inspecting the fuel line and injectors. However, if fuel line deterioration is causing clogged injectors, I suspect there would be additional symptoms besides roughness within a very narrow range of engine speeds just above idle. There are a lot of cars and trucks on the road that were manufactured prior to 2005 and they are all (most) running on E10, at least in South Carolina. I have read about the horrors related to using ethanol blended gasoline but have yet (unless the truck is the first victim) to experience any first hand. That observation is based on the current six cars and trucks (two belong to children) and range from a 50 year old Alfa to a 10 year old Chrysler mini-van. Anyway, thanks for the suggestion, and of course you may well be correct. BTW, I am not thrilled by the prospect of pulling the intake manifold again and digging into the fuel system.

My apologies to the OP as I have thoroughly, if inadvertently, hi-jacked this thread.

 

the 1st thing you should do !!

purchase and install a newer ethanol tolerant fuel line to the engine ( 2010 / 2011 ) model year

then run 2 or 3 cans of seafoam mixed in with the fuel ( i can per tank full )

the sea foam may help in further disintegrating the rubber particles that may be clogging your fuel injectors

this process is what i would first before anything else

 

Thanks.

 

you are welcome

 

I removed the fuel delivery line to the rail and there is no indication of deterioration. Probably a good idea to replace that line at the first opportunity though. I ran a partial tank of gas and Techron injector clean through the engine over a four day period. The symptom did not change until I put 10 gallons of gas in it yesterday. The severity of the roughness seems to have decreased. I don't know what this means. Too early for any conclusions so I will continue to drive it and note any changes in behavior.

I rechecked for vacuum leaks over the weekend by disconnecting the IAC, which brings the idle down to 500 rpm, and squirting water from a garden hose at various spots on the intake manifold side of the engine. There was absolutely no change in idle speed so I think vacuum leaks are not a likely problem. I am again looking at the intake manifold runner mechanism as a potential problem. BTW, there is another post describing problems related to the IMRC solenoid and a description of how the intake runners work. From my observations, the flaps open at or just above 2000 rpm, not 3000 rpm as described in the earlier post. Can anyone confirm this, one way or the other?

 

techron is not powerful enough to dissolve rubber particles

only seafoam is powerful enough to dissolve non ethanol rubber

run 1 can of seafoam mixed with a tank of esso 91 octane fuel

half way through that tank of fuel ( find a long road out of the way floor the accelerator pedal )

old schoolers do this to carbeurated engines to clear out a partially clogged fuel jet