I'm not a newby to auto work having done all mine of every kind since a kid. I'm now 79. But, I'm stumped on this one as to where to turn, and I'm hoping some of you folks with experience can help.

I have a 1994 Ranger with a 1997 3.0l vulcan engine that I put in about six years ago. The engine has about 110000 miles on it and hasn't missed a beat until last week. Suddenly, the check engine light came on flashing. The flashing stopped, so I returned home. My scanner trouble code said that the number 5 cylinder was not firing. I checked the #5 plug which looked good but changed it anyway. I checked the plug wire ohms then switched them around. I had a good ignition module that I switched in. I listened to the injector. It was clicking. I put a dowel rod against the injector and tapped on it with a mallet to see if I could maybe open any blockage. After each thing I did, I erased the code then ran the truck. It continued missing and the check engine light came on again with the p0305. At that point, I checked engine compression, did a vacuum check, and checked the fuel pressure. All were good. As a last resort, I put in a new injector on cylinder #5. It's still missing on #5.

If this was yours, where would you turn next? I'm stumped.

 

the adjoining cylinders...plugs, injectors, etc. If they are missing the ecm will pull fuel from the next cylinder in trying to balance the mix.... chances are, you have fuel injector issues.

 

You've been busy doing some good trouble-shooting, so lets think about this some more.
Is the P0305 the only trouble code you have, if not post all code Numbers you've seen so far.

Seeing as how the misfire cleared itself while driving sorta suggests a loose elecrical ground connection on the #5 coilpack plug at the pack & its wire run all the way to its firewall ECM connection belong on the suspect list.
So put your inductive timing light on #5 plug wire to safely see if spark is now missing, or becomes intermittent to #5 as you flex the coil-pack plug & its #5 ground wiring run between the coil-pack & firewall ECM connecter.

Lastly, the internal connections to the #5 ECM ground switching driver, including a cracked printed circuit board raceway, or the driver itself, all seem to belong on the suspect list. More thoughts for consideration, let us know what you find.

 

pawpaw, Thanks for the quick reply and helpful advice. I'll start with your suggestions as soon as the weather allows outside work. To answer your question, the code, p0305, is the only one stored in memory.

I'll reply as I make progress.

 

Don't know the engine well but Rockauto says it might use the "old" style distributor type ignition. There's a single coil and a distributor cap. If this is true then problems in the cap are a possibility. Or maybe there is a coil pack - one unit, six spark leads. Since the engine is a transplanted 97 in a 94 it's hard to know the details.

It's weird and kind of disturbing that Rockauto's descriptions are so incorrect. Like " Ignition Type: Coil On Plug, 1 Per Cylinder Info w/ Distributor". Doesn't really mean anything, they just put all the words in. Then show a single coil.

Anyway, the details might help. Good luck.

https://www.rockauto.com/en/catalog/...tion+coil,7060

 

Hold on, last night after rereading your initial post I think I may have completely misunderstood what you did on the 97 3.0 L engine swap into your 94 Ranger, sensors & wiring harness swap 6 years ago. If this puppy still has a dizzy / distributor ignition, all that wire run checking was for a coil-pack waste spark ignition like my 99 4.0L has. SO, a dizzy ignition wont have it.

But one thing missing on your electrical trouble-shoot was that you never said you checked for spark, so use your inductive timing light on #5 plug wire to safely visibly confirm its there & not intermittent.

If intermittent, remove the dizzy cap & check #5 post & rotor for excessive erosion of the spark gap, or cap carbon tracking, debris, or maybe moisture from a crack in the cap around #5 post. Check for anything in there that could cause electrical leakage & a wimpy spark that'll easily blow out & cause a under-load engine miss.
This would include #5 spark plug wire insulation arcing to ground between the dizzy cap & spark plug.
Have a look along #5 plug wire at Night for arcs & sparks as you spritz it with a water mist, it helps unmask wimpy or damaged insulation.

All that said we haven't talked about a sticking valve, or carbon deposit flakeing that can hold a valve open enough to cause a misfire code. lol
More thoughts for consideration, let us know what you find.

 

Do you feel a 'hard miss' while the engine is at idle rpm? Do you feel a miss while accelerating?
Does a clamp-on timing light(inductive) show a steady spark or intermittent?
You changed the spark plug... was a new plug installed or one kept from the last time new plugs were placed in service? what does the plug look like? rich/lean/hot/cold/coated with crud...?
Can you enrich the mix by adding some carb cleaner/other inflammable... and if so, does the engine misfire go away.
Presuming you can feel the misfire.
Some FoMoCo 4-cylinders used in Escapes will post misfire, you essentially cannot find the reason as it is almost imperceptible. The valves go bad, and they leak slightly, and will misfire at idle, but you can't feel/tell when above idle rpm.
If you did a leakdown how does #5 compare to the others? If not, do a leakdown. I kind of remember that some years of Vulcans had valve problems when over 100k miles.. not a real clear memory as Ima couple years behind you.
tom

 

Problem solved and thanks to you who replied with help. I'm aggravated with myself for focusing in on the code that the scantool gave me. It consistently gave a code of p0305, so I was checking anything and everything having to do with cylinder #5. It turned out to be cylinder #1 that was "dead," or what should have been a code P0301. I know that #1 and #5 fire off the same coil, but why would it consistently store the wrong trouble code. Does anybody have any explanation for this? I like to try to understand these things.

 

Why was #1 dead? Spark plug, wire, coil pack?

As I understand things the PCM measures the time between CKP signals to determine a misfire. After a misfire the next pulse is delayed.

Any chance you got your firing order mixed up? Ford has their own way. This thread shows the order -

https://www.ford-trucks.com/forums/1...i-missing.html

 

No, the firing order was correct. If I had ignored the code and used "old-school" methods of diagnosing the problem, it would have been solved in a few minutes. I'm aggravated at myself for believing the ecm. The problem was just the sparkplug.

 

I guess I was lucky to avoid the 'waste spark' systems. Kind of hard to imagine the spark/electron flow going (imaginary) from coil pair side 1 to plug1 center electrode to side electrode across the block/heads to plug2 side electrode to plug2 center electrode to the other plug wire back to the coil pair side 2. Somehow it does not register properly... in my mind.
Thing to watch for is that electrode wear is normal on one plug, and wears 'wrong' on the other plug.
That is why double platinum tips were made... or iridium. I still don't know what it is except it apparently takes a LOT of miles to have appreciable wear.
I do know that the 'squareness' or 'sharp edges' of both side and center electrode can make a difference in how well a plug fires.
If you have worn plugs, and no $$ for new, get a thin file(points file) and square off the edges of the center and side electrods, reset the gap as needed, and you will likely see the plugs start to work a lot better. Apparently, my description, a rounded electrode edge allows the electrons to dither on the electrod, not enough gathering at a sharp edge(they can be on 2 surfaces w/o interfering with each other) so they stand around and finally one jumps.. the others follow. As best they can. Give them a sharp edge and electrons from two sides that are not adjacent and jump at the same time or near enough. Makes sense to me.
tom

 

Spark Plug Mini Tutorial - Ford Truck Enthusiasts Forums Some info & thoughts I posted in 2011 about our waste spark ignition system, some iteration & changes Ford made to improve things, some bad things that happened to my 99 Ranger 4.0L waste spark factory plugs in less than 30 K miles & some good things with the improved plugs.

 

A very informative tutorial. Thanks for ending me to it.