My 2.5 began being hard to start about 3 weeks back, since then it has ran worse and worse. Last week it got to the point that i could floor it and never get over 40mph, so i stopped in oreilly and ran codes... misfire 3rd cylinder p0303 or something like that.

Time to take a look..Ok so first thing i looked into was the coil packs, the front coil pack seemed to only be firing on 3 cylinders with , you guessed it number 3 cylinder not firing. The rear coil pack had no fire whatsoever? (im only testing by pulling the plug wire off to look for spark by the way) So, does the rear coil pack go to the "waste spark" system aka the exhaust side? am i right about that or do i have it backward? should the rear coil pack always have spark or is it intermittent and controlled by the computer when it senses ....whatever it senses????? Anyway, thats the easy part of the equation......

Theres way more to the story, for the past couple weeks i have been hearing this sound of liquid dropping down into my oil pan which i have thought was oil this entire time,although i have never noticed the oil being that loud dropping back down to the pan. Now im thinking its gasoline because i put a fuel pressure guage on the fuel rail and it will jump up to 65psi MOST times with koeo , but not EVERY time. KOER it stays steady at 65 no matter if its idling or your "goosing" the throttle. BUT when you turn the truck off my fuel pressure drops like a rock from 65psi to around 20 psi in 1 minute or less. I put two and two together (dripping sound in oil pan plus the drop in fuel pressure) and assumed it was my injector(s) leaking the fuel down through the cylinder so i removed the intake and the rail to where the injectors are free and i can see the pintle and kicked the key over expecting one of the injectors to dribble like a high schooler with the clap , low and behold......NOTHING. not a drop spilled. tried several times, still nothing besides the pressure blew an injector or two off the rail.

Any kind soul want to help me out here with some ideas? i just dont believe its not the injectors, but by now im pulling my hair out and probably just want to believe its the injectors and not the pump since theyre out already. i plan to do a continuty test on them tommorow but im tired and wondered if maybe im not just missing something here. Any ideas?

 

The exhaust side coil pack is used for starting, intake side is only used once engine is running(RPMs above 500).

Waste spark means there is 1 coil for 2 spark plugs, each of your coil packs has 2 coils in it.
So you have a Dual waste spark system, because of the higher compression in the Lima engines it reduces pinging.
Waste spark can reduce emissions but main thing is that it is cheaper than one coil per cylinder.
Waste spark runs the 2 spark plugs in series so can be prone to failure, and can fail on one plug only even though logic might tell you both spark plugs should fail if that 1 coil fails, but not the case here because of the series connection.

Could be spark plug on #3 or the coil that has the problem.

One issue with Dual waste spark system is that 1 coil pack can fail and you won't know anything is wrong until the other coil pack has a problem.
You can swap coil packs around they are the same.


Fuel pressure drop after stopping engine can be a bad check valve in fuel pump, fuel line leak or injector leak.
Unless engine is blowing out black smoke I would rule out injector leak, fuel line leak is often detected by smell first, 65psi will leak enough fuel to be smelled even inside the cab.
Yours reads like a check valve issue, or a leak on fuel line inside the tank.
Check valve is a "backflow preventer" it holds pressure in the fuel system when pump is off, it is part of the fuel pump so whole pump must be replaced.
There is usually a rubber line inside the tank between fuel pump and outlet, the connections can leak or the metal lines can crack, since this is between pump and rail a leak there will cause pressure loss with key off and also cause a lack of volume in fuel flow, Reving engine while stopped doesn't use alot of fuel volume, but while under load(driving) fuel volume demand is higher, so thats when you would notice a drop in available volume of fuel.

 

Im still not understanding the 2.5 waste spark.....so the exhaust side starts the engine but should the coil for that side continue applying spark even after the vehicle starts? You see, i am trying to rule out that that particular coil is bad. And i assume the front coil or intake side coil only activates after the truck is started and should continually run as long as the truck is running. If this is all true this would be why i have no spark on my rear coil? Because i was only checking the rear coil while engine was started not on startup, because i was working alone.

 

Ok im starting to form an idea of this, in my head im imagining that from the rear coil the spark travels to the exhaust side number 3 plug, through rhe block to plug 3 on intake side and through that plugs wire back to the front coil number 3 position.......just a big circle. However, im not understanding the point but i guess thats not a big deal as long as the theory is correct lol. Because i DID NOTICE that when i took the plug wires off, number 3 on the intake side wasnt even on the plug. Could this be the whole problem?

 

No, the spark from 1 coil would go to spark plugs 1 and 4 on exhaust side or on the other coil in the coil pack to spark plugs 2 and 3.
1 and 4 or 2 and 3 are "matched cylinders" on the Lima engine, this means the pistons for 1 and 4 are both at TDC at the same time, then 180degs later both 2 and 3 are at TDC.

You can tell "match(or paired) cylinders" by firing order
1-3-4-2 shows 1 and 4 are matched and 3 and 2 are matched

On a V6 firing order might be 1-4-2-5-3-6
1 and 5
4 and 3
2 and 6
Are the matched cylinders
This matching helps balance the engine

Intake and exhaust side coils are separate as are the spark plugs for each, only thing they have in common is the ICM(ignition control module), on a 2000 that would be in the computer.
Exhaust side spark plugs start engine, both exhaust and intake side spark plugs should be working while engine is running.
Because the spark plugs are in series lifting the wire won't always show a spark, best way to test for spark is with an old timing light or an inline spark tester.

If you look on the exhaust side coil you will see exhaust side #1 and #4 spark plug wires are on the same coil, and #2 and #3 are on the other coil in that one pack.
The 'waste' part means that #1 and #4 will fire at the same time but will not both be on their power stroke, both will be at TDC but one will be on it's exhaust stroke, so spark is "wasted" on that cylinder, it doesn't hurt any thing and could ignite some unburned fuel, but more of just 'waste'.

But with the two coil packs and dual spark plugs it means there are two sparks in a cylinder to ignite the fuel.

 

Thats odd because while tinkering around i unplugged the exhaust side coil and started the truck, plugged exhaust side back in and unplugged the intake side coil and the truck would NOT start. Am i to assume the last person to change the wires did it backwards then? I think we could have done without this dual plug setup, its for the birds lol.

 

Ok here are my updates. (1)injectors were tested in several different ways and are good, had them cleaned. (2)cleaned maf, iac valve,egr valve, pcv valve. (3) Replaced intake and iac gaskets while the intake was off.(4) basically i have found the only problem with the fuel system is the fuel pumps check valve is inoperable OR there is a leak at the hose in tank, neither effects the way the vehicle runs , it holds perfect fuel pressure while running so at this point lets disregard that problem. (5) all new autolite double platinum plugs as well as premium borg warner wires were installed correctly and as i said earlier i have one new coil pack and both the new and old coil pack test good.(same resistance values) (6) basically it boils down to the rear/passenger side/exhaust side coil NOT firing at all. The front/driver side/intake side coil fires on all 4 cylinders and on my truck this is the coil that starts the truck....possibly because its the only coil firing im sure but regardless, here is what i have found so far as to diagnose the non firing coil, its not the coil, the voltage tested with multimeter across the 3 pins on the coil pack connection show me that all values are the same besides 1 of them on the coil pack harness connected to the non firing coil. I have obviously not come up with a solution for this problem. And cant find a reason on this foeum, noe the entire internet.

 

Ron d, i appreciate your help. I have found the problem with the help of a local shop that had tools which i do not (equipment to check an ecm's functioning) found out that my ecm is sending signal for the coil to fire but the coil is not receiving the signal.....=wiring harness problem!

And i paid them well for the diagnostic (85 bucks ouch) and ill be darned if im paying them the 250 they wanted to run a piece of wire from one end to the other, some of these shops are almost comical. The fuel pressure issue is no longer considered an issue as there is no black smoke, no flooding and actually pressure seems to be holding more steady at 40-50 psi since i took the entire fuel system apart and put it back together....wierd stuff.

 

Well shops have to warranty their work and do a cleaner job on wiring than a DIYer would in most cases so...............

Autozone has a nice resource center with loads of info, including wiring.
Look here: | Repair Guides | Ignition System (2000) | Ignition System (2000) | AutoZone.com

2000 Ranger 2.5l ignition wiring, it shows the pin numbers for the PCM(computer) that are used for the coils.
Just google: Ford EEC-V pinout
to see how the pins are numbered, then confirm with wire colors

 

actually ron d , i was fooled. The local shop that said they found the issue turned out to be a no go later on that same day. As i stated, the shop wanted to charge me 250 to re run the wiring from pcm to coil pack (actually im sure they just planned to solder the break) after bringing the truck home and testing continuity and resistance on the wiring myself (which tested fine) I called around and found a new to me pcm from a salvage yard for 25 dollars.................both my coils now fire as they should.

My own personal diagnosis, when the rear coil went bad it shorted the pcm ground switch for that coil and fried it. In turn i was left with a bad coil and a bad pcm.

Wanted to update this for anyone that comes after myself with these same issues.