So I just bought a 97 Ranger with the 2.3, 8 spark plug model and I actually have a couple of questions. If one of the 8 plugs is not firing is it that noticeable? I also assume the 4 plugs on the drivers side are the "primary" plugs? Second question. I was testing the resistance with my voltmeter and one of the plug wires showed zero resistance.( the others were about 4k ohms). Does that mean that particular wire is not firing at all,or firing too hot,or what? I'm not very knowledgeable on all things electricity related,ohms,etc. The truck has a definite regular miss,mostly at idle. Thanks for any insight.

 

Welcome to the forum

Actually Exhaust side spark plugs were Primary but that only applied to 1994 and older that used external ICM(ignition control module) and older EEC-IV 60 wire computer
In 1995 the ICM was in the new model of computer, EEC-V 104 wire, and both sides spark all the time

All 8 spark plugs fire on both the compression stroke and exhaust stroke of their cylinders, no alternating.

If 1 spark plugs wasn't working if would effect performance but not cause a misfire as long as the other spark plug was working.
BUT..................Ford uses a Waste Spark system, and wires 2 spark plugs in series, so if one spark plug wire was bad then it could/should effect TWO cylinders
Spark plug wire with 0 ohms would be a No Spark, resistance(OHMS) is needed to build up spark voltage enough to "jump the gap", some engines used spark plugs with internal resistors, so used different spark plug wires.

To test spark plugs unplug one Coil Packs 3 wire connector
Start engine, if you have a misfire then a spark plug or wire is bad on that coil pack(you can also test the coil pack)
Turn off engine and reverse it, unplug other coil pack and plug back in the unplugged one
Start engine see if its misfiring on that coil pack

The dual spark plugs increase performance so with only 1 coil pack working the idle should be a little lower and performance will be OK but not as good as with both spark plugs firing.

Your coil pack has 2 coils inside, the 3 wire connector has 12v power wire in the center then 1 ground wire for each coil.
You can measure OHMS between 12v and ground on each coil to test Primary Coils resistance, .7-1.3ohms is expected, low ohms

Each coil in the pack sparks 2 spark plugs at the same time
2.3l Lima engine uses 1 4 and 2 3 to balance it
So cylinders 1 and 4 are at Top Dead Center(TDC) at the same time, then 180deg later cylinders 2 and 3 are at TDC
Coil packs are wires so 1 coil sparks 1 and 4, or 4 and 1, and the other coil in the pack spark 2 and 3 or 3 and 2

1 and 4 or 4 and 1 order doesn't matter, thats a myth, lol, but Ford does have them reversed on the dual coil packs

 

Thanks for the reply. I have a scanner/code reader on order that has the mode 6 function(my current one does not).Hopefully it will tell me which plug is misfiring. I'm thinking the wire with the low resistance is a high performance wire,it is a different brand than the others. Thanks again.

 

No, not high performance just for a different spark plug setup, a spark plug with internal resistor

Spark plugs used to come with internal resistors, they will have a "R" in the number, because of Radio Noise and other interference with electronics building spark plug wires with resistance and no resistor in the spark plug worked out better for less radio noise

Normally you want about 3 to 7k resistance in a spark system, whether that's in the wire or the spark plug is up to the user, but you don't want both or neither, lol.

 

I'd like to go back to your first post regarding the timing of the 2 plugs on a given cylinder. From what I've read the second plug fires a microsecond after the first plug fired. Thereby "cleaning up" any fuel/air mix that wasn't ignited by the first plug's firing. So if the second firing fails but the first one ignites okay aren't you basically just back to a conventional one-plug-per cylinder setup? No harm,no foul? By the way,is the plug firing/timing handled by the ICM or ECM on those trucks? Thanks.

 

No, there is no clean up firing, both spark plugs fire at the same time, a delay would cause spark knock/pinging, which occurs when lower octane fuel self ignites milliseconds before spark plug fires.

Dual spark plugs were first used on airplanes for safety reasons, there were two separate spark systems so either could be running or both could be, so a backup if its not easy to just "pull over" lol.
But they also provided faster and better combustion in older head designs, so better performance and lower emissions were the reasons the Lima engines got these.
With the advent of swirl air designs and 4 valves dual plugs just aren't worth the space they need in cars and trucks, a single spark plug can get a good, fast and complete burn

Up to 1994 Rangers used the 60-wire EEC-IV computers and either a distributor or an ICM(ignition control module) for spark
In 1995 Ranger got the 104-wire EEC-V computers which could run the spark system so all were distributorless and none had ICMs

 

I might have dreamed it but I thought I once saw an electronic tool that clamped onto the plug wire near the plug and relayed a signal confirming whether or not "fire" was reaching the plug. It was sensitive to the energy coming through the insulation of the plug wire. Anybody else familiar with such a device?

 

Yes, most later model timing lights came with that type of "inductance" clamp

And you can buy Tachometers that use that type

Tach/timing light combo seen here, with inductance clamp: https://upload.wikimedia.org/wikiped...iminglight.jpg

 

How about a common voltmeter with an induction attachment? Could it handle the 30,000 volts in the spark plug wire? If so I could just attach it where the plug wire meets the boot and see if fire is reaching the boot.

 

Inductance tool doesn't touch the bare wire, it reads the voltage/magnetic field that is created when power/current is passed within the wire, so yes any volt meter could be used, set it for highest voltage setting first then bring it down if you don't get a reading, test on WORKING spark plug wire FIRST, to calibrate

 

I'm trying to find a way to check see if spark is reaching the plugs without having to actually pull the plugs. Plugs 3 and 4 on the drivers side are almost impossible to reach without removing the upper intake manifold,which I have already done 4 times in the month I've owned the truck. It has a misfire and runs rough when it is cold but smooths out somewhat after it is fully warmed up. I've replaced all plugs,2 fuel injectors and a couple of the plug wires,and the miss is still there. I did a compression check and all cylinders are strong,between 179 and 183 psi. Surely its not a burnt valve causing the miss.

 

Get an old or new spark plug and put the wire on it.
Plug needs to be grounded, I would use a jumper cable to clamp threads of spark plug and then clamp other end to engine or battery negative

Blue-white is a strong spark
Yellowish is a weak spark

 

So I broke down and bought a timing light to check how well spark was getting to the plugs. Light was flashing very fast on Cyl # 3 and #4,passenger side and driver's side,almost a blur. But it flashes much slower on cylinders 1 and 2,both sides. I'm guessing that's not normal.? Maybe a failing coil(s)? I've gone round and round with this truck since I bought it 2 months ago trying to track down a misfire. No codes showing. Compression on all cylinders is strong. New fuel injectors and they're clicking.I'm stumped.

 

So the 2 coilpacks on a '97 fire at the exact time and sequence correct? Seems to be conflicting information on that.I don't see how the rear coilpack can do anything other than mirror the front coilpack, lockstep in unison? Supposedly you can unplug the rear coilpack and the engine will still run fine.(haven't tried it).