One plug fires twice as fast?

On my 99 3.0 Ranger, I had an injector go open so I replaced it with a new one in cylinder 3. That cleared my Cylinder 3 MisFire code but it still is running rougher than usual. In checking the coil pack for firing, I noticed that Cylinder 3 is sparking about twice as much as the other 5. Any ideas? I also noticed that this truck has AP103 AutoLites in it, which are single platinum plugs instead of the dual platinums required by the wasted spark system.

The rapid firing of cylinder has me baffled. It's mate, cylinder 4 is firing normal like the others.

Thanks for any rapid feedback, I need to get this truck back online asap.

Tom

Cross fire maybe. That's about all I can think of.

Must be within the coilpack then, wires are new. Just put in the double platinums and the poor running is still evident.

Edit: Don't have another Ranger coil pack so I tried one from a 95 Taurus SHO, and it definitely didn't like that. I'll get out the smoke machine and look for vacuum leaks next.

Edit again: Smoke generator did not show any leaks and the double speed sparking does not follow the spark plug wire; stays on cylinder #3.

Curses.

Tom

There's about 200K miles on this engine so I'm now wondering whether I burned a valve on cylinder 3 when the fuel injector quit. The misfire started right after a spirited 80 mph run down the highway.

I guess my next step is a compression test on a few cylinders.

Tom

Replacing #3 injector would cause rougher running if the other 3 are high mileage original injectors. Its flow rate will be different (as opposed to old/ tired / gummed up ones).

Im agreeing that it might be the coil pack causing your rapid firing. Do a resistance check on your coil packs and see if there are any internal problems. Soak your plug wires and coil with some silicone spray (or better replace) to assure that there isnt any crossover.

Another quick check is to look under the hood at night while the engine is running. Just observe around the coil pack and where the wires get close. Easy to spot arcing that way.

If you do the night check..DONT put anything under the hood that you want to remain on your body. Belts and Fans dont care whats offered and they are ALWAYS hungry..

I didn't think about the difference in injector flows causing a problem. Everything else though has been replaced; new coil, new wires, new plugs. Still runs terribly.

I will try and get a scope down the #3 plug hole and see if there is something burned or at least obvious.

It has so many miles on it, I might just pull the heads and have them re-done.

Tom

Update: So to try and speed things up, I bought a junk 98 3.0 that had a knock. Not a problem, I needed the heads so I could have them re-done ahead of time and be ready to swap into my engine in a single day. Well, along with the spun rod bearing and scored piston and cylinder,the heads from the 98 3.0 were so far gone that the machine shop will need to grind and insert some seats. The exhaust valves were actually sunken into the head. When he pulled the valves out, they almost had knife edges on the exhaust valves.

So the machinist suggested that I check and see if my compression comes up on the 99 motor still in the vehicle when I slightly loosen the rocker arm hold down bolts. If it comes up, the low compression is not caused by worn out cylinder walls and rings, but rather by worn valves and seats.

Such a pain. Still can't figure out the terrible mis, or the double time sparking of the #3 plug/wire.

Tom

I know this shouldn't help you with your problem but have you tried pulling the power to let the computer reset to a default state. This should force the ECM to relearn hor to run.

been along time since i messed with a 3.0
but if your #3 cyl is sparking at odd times/ sparking too fast.. this cannot be a mechanical issue, piston could have a hole in it but if the ignition system is good its will still fire properly etc.

i cant remember does this have 1 coil pack with all 6 cylinders? 4 wire connector? ( power and 3 control wires) if so its a waste spark system and either the computer is telling it to fire at the wrong time or you have a short in your control wiring to the coil... also waste spark systems rely on the companion cylinder to ground in some occasions so say 1/4 2/5 3/6 are acrpss from each other (i know thats not right but you get the picture) 6 may still fire correctly because 3 is fine but 3 may not fire correctly because of too much/too little resistance in 6 spark plug wire....

just a few suggestions but if you simply have a firing issue i highly doubt it is caused by anything other than electrical issues

It has new plugs, wires and a new coil pack and I have disconnected and drained all residual power from the PCM.

What a pain.

Tom

since the new plugs, wires and coil pretty much the only thing that can be causing it is control wiring to the coil, or the computer is bad... witch is still odd because it should also be messing with the companion cylinder other than that only thing i can think of is the trigger... think these have the cam synchronizer like a 3.0 in a stantard tarus right? but that would be super odd it should effect all cylinders... my opinion get a wiring diagram and get to ohming

Well, I finally was able to get back on this Ranger and put six new rebuilt injectors in it, just in case the one I replaced was causing the misfire. Nope, didn't help it a bit.

In the process of removing the upper intake to replace the injectors, I did find where the gasket had been damaged and someone had tried to fix it with silicone. I had a good gasket from the 98 engine that was in excellent shape so I used that.

Tom

Was the silicone patch on/around #3 intake tube by any chance? You may have found what caused your misfire initially at least. Definitely do a compression test to get an idea of where the engine is at mechanically before throwing any more hard parts at it.

Well well well. The saga starts to make sense now. I cleaned and installed the 6 injectors out of the junk 3.0 I got off of CL and it still ran poorly. So I drove it over to my buddy witha snapon scanner. Said it had the wrong injectors in it, probably from a regular 3.0, my truck is a flex-fuel engine.

Took the original injectors (5 plus the new one from O'reily's) to my injector re-builder and low and behold, the new one was flowing way more than the other original Fords. Bought a new rebuild that was matched to my 5 and took the "new" one back to O'reily's. After O'reily's looked it up, they determined that they had given me the wrong injector. The receipt said for a VIN code V vehicle, and they gave me one for a VIN code U. GRRRRR!

So, the wrong injector that I put in to replace the original failed injector, was flooding that cylinder. The PCM detected the difference and must have been firing the coil more often to try and burn it off. ?? I don't know how it can do that to one cylinder and not its corresponding mate.

Anyway, I will be installing these rebuilt, matched injectors that originally came in this Flex Fuel 3.0, back into this engine in the next few days. I will report back on how it drives.

Phew!

Tom

Fixed!! Though I didn't think so at first because it still shook like it was down a cylinder. I put the original but re-built injectors in, after cleaning the valley and all the injector bosses in the head and fuel rail; didn't want to have a leak. Started it up and ...damn! It still didn't run right, like it was down a cylinder again.

Ran codes and now cylinder 6 was showing a misfire. WTH! Put on the timing light, juice was going through the wire, pulled # 6 plug, still looked brand new. Let it come up to operating temp and the miss was still there. Curses!

Shut it off and put a smoke machine on the intake. Bingo! Massive leak at the PCV line (that plugs into the intake at cylinder #6) that had gotten removed but not put back on when I swapped in the injectors. Boy, I was as happy as lizard in a bait shop after closing hour. Plugged it back in and WRONG! It still had the miss.

Shut off the engine and put a house fan on it to cool it down. After 15 minutes I was able to reach around behind the intake and just barely touch the #6 injector and its plug. Damn, it wasn't clicked down all the way. Started it back up, put my stethescope to the injector body and all was well.

Runs smooth again and has that huge 142 hp again, though still worn out with a zillion miles.

So what did I learn from all this? (1) Don't trust O'reily's personnel for things you don't know much about yourself; double check with the guys on the appropriate forums. (2) Don't start replacing things until you know they are defective; I threw away good plug wires and bought another coil pack that was not needed. Also bought a CL junk motor thinking my heads were bad. (3) Quit buying cheap Chinese tools when a good tool is available.

Tom