I have a 1994 ranger with a 2.3 that was running rough. Both coils were replaced as were the plugs and wires by the vehicles owner. Nothing helped the rough running engine. I did a little checking and found that only cylinders 2 & 3 were firing on both coils(compression and exhaust). Cylinders 1 & 4 were completely dead. I checked for loose and or corroded wires at the ignition module and found nothing wrong. At this time I tapped the module with a wrench and it began running fine. It will work then stop working when you do this repeatedly. I decided that it was probably the module and told him to go pick one up. The next thing I know he has already changed it out. He didnt disconnect the battery when he did this. He also didnt know that the alumunum plate on the back is a transistor heat sink ( He tried to run the engine with the module not bolted down to the maniflod) ( he also didnt use heat sink compound when he finally bolted it down) Now the engine will not fire at all with the NEW or the OLD Ignition module. I cant find any bad connectors or wires and the fuses and relays all check out OK. Is the PCM fried? or maybe both ignition modules?
Can anyone help me with some troubleshooting tips for the module or pcm?

-Tom

 

Probably fried the new ignition module, but shouldn't have taken out the PCM -- however, anything's possible. Shouldn't really have hurt anything to have the batt connected when he changed modules -- all of the volts go through the ignition switch.

You might try pulling the SPOUT (single pin) connector apart to see if it has spark then. If it does, then the PCM is loading down the ignition. This can be caused by a bad PCM, or one with no power. The pcm on most Fords gets its power through the EEC relay. There may also be a fuse involved.

If pulling the SPOUT doesn't work, it's probably the module, but I'd try a few
meter readings first
- see if you have volts to the coil with the switch on
- volts to the TFI (module) -- I think there are separate wires for run and
start
- ohm the coil -- I've heard that they can be blown out.
- check ground connections.


good luck,

ford2go

 

cool that helps BIG TIME!

I looked at the spout connection and unwrapped some of the loom to get a good look. It appears that this spout wire is uninsulated once it enters the loom? Should it be this way or has the insulation melted off? SPOUT stands for Sparkout-put from the pcm to the module correct?
Is there anywhere I can get a wiring diagram or maybe at least pinouts for the pcm?

Thanks man-

-Tom

 

seeing as the ignition module contains the NPN transister in charge of opening and closing the primary circuit, It should not have damaged the PCM seeing as the transistor is not integral. You need to find voltages to the module connector. Find battery voltage at the collector of the transistor. Then, with the engine cranking find the cam/crank sensor signal pulse from the PCM coming to the base of the transistor (hense the opening and closing of the primary) . There would also be a ground wire. Also to test the ignition module, power up the transistor and look for continuity. This is a basic approach a manual or all data would be more helpful

 

I had a very similar problem this past summer on my 94 B2300. It is not exactly as you describe but electronic problems can often be made worse by ground problems and variations in feed voltages so they may show up with slightly different symptoms.

The vehicle would run fine and then intermittently run very rough, especially when idling at traffic lights. I thought bad gas, fuel filter, etc, etc. This went on for a few months, then I returned home from a 110 mile round trip, came up the driveway and parked—and it would not start at all after that. There was no spark in all four cylinders. The check-out procedures as in the Helms manual and also in the technical notes by Ken00 at the top of the forum seemed to indicate that the ignition coil and the DIS module were OK, therefore I concluded that it must be the crankshaft position sensor. Went through the whole major process to change it and then the engine would still not start. In the process of checking the DIS module, I broke one of the screws off that was badly corroded. I didn’t think much about it at the time so ended up replacing the module and used just the two remaining screws-big mistake. I got a spare DIS from the junkyard and checked it on a tester at Autozone to verify it was good. I then disassembled it and learned that the DIS module is grounded through a single screw and not through the wires that go into the top and bottom of the module. So if you don’t have reallhy good screws, or if it is not attached to the manifold or a ground wire is not connected to it, it won’t work. I solved my problem by running a wire from a known good ground and soldering it to the DIS module. Once I did this, the engine started and has run perfectly ever since. The new crankshaft position sensor worked perfectly, and I concluded that the original CKP was probably not bad. The whole problem of running poorly had been a poor ground on the DIS module and when I broke the screw, there was no ground at all. I concluded that the trouble I experienced while idling at a traffic light was a ground problem made worse by the lower voltage associated with idling.

If you look closely at the DIS module, you will see four screw holes and only one of them is surrounded by a metal contact area-looks like the entire corner is metal and that is the ground screw.

Hope this helps with your problem…

I also have the pinouts for the PCM if you really need them. Send me an email and we’ll figure out how to get them to you………….Ed

 

Thanks ED! I forgot to mention that when we removed the DIS module, 1 of the bolts snapped and we didnt replace it... Care to guess which one it was? I would have thought the heat sink would also be the ground but I guess I was wrong. We replaced the broken bolt and she fired right up!!

Dude I cant thank you enough.

-Tom

 

You are very welcome, Tom. Glad it worked for you.

I promised Rockledge I would write this whole thing up at the end of last summer but got distracted and never did it but you gave me the nudge to at least get this much in.
As I have read the forum about so many 2.3 L that run poorly, I suspect a bad ground on the DIS from a corroded screw may be a common problem. If I had any more 2.3 engines I would electively solder a ground wire to the DIS module. I was also impressed with the variability of the symptoms prior to the time my truck just stopped running. It was exaggerated at idle so now I think it was voltage dependent. I wonder how many CKP sensors have been replaced needlessly.
I must say I was concerned that perhaps your problem was not the same as mine because you had spark on two cylinders and I had none--another incidence of variable symptoms of the same problem.
Hope this thread will help others, even if their symptoms are a little different.
Ed

 

I believe I did have a problem with the original DIS module. I think the transistor outputs for cylinders 1 and 4 for both the compression and exhaust coils were KAPUT! I dont know if the bad ground could have contributed to this problem or not. We cut open the old Module but didnt find anything "cooked" but it appeared to had one of the fine wires broken or disconnected that went to a transistor. It was really hard to tell much of anything though with all the gel that they pack inside there.

I ordered a electrical /vacumm troubleshooting manual on ebay so I will have it for more detailed schematics should I ever need it later on down the road...

But all is well with the new module and ground though!!

Thanks again!
-Tom

 

Have a very similar problem with a 1991 ranger. Truck starts fine, idles for 5 or 10 minutes then dies, will not start however unless you turn the key back to the of position before you attempt a restart. Or if you’re driving, tach just drops and engine dies, same thing with switch. Sometimes tach seems to be indicating wrong engine speed at which time truck will buck and jerk. Oh yea, fixing the A/C made the problem worst.