I know this is going to probably open up a can of worms with the Ford vs GM debate, but oh well. I’m having a lot of ignition problems and I’m tired of trying to hunt down what seems like a ghost in the system and keep throwing parts at it. The sound of putting a GM style HEI distributor with only two connections sounds really appealing right now. However, this is a 93 f350 with 7.5l and I am needing to know how much, if any, of the ignition is controlled by the computer in 93? What kind of problems will I run into with doing this swap? Thanks in advance for all replies.

 

The computer does not control the Ignition system with the SPOUT removed.

 

Yup the ignition is complete stand-alone if you remove the spout. Obviously your gas mileage and performance will suffer, but it will still run more or less reliably. The HEI won't fit because it won't clear the intake hoses and what not.

We can help you fix it right if you give us something to work with.

 

I understand wanting to go with something totally different when you've had problems, but this sounds a lot like the people that want to rip out all that "computer/fuel injection stuff" and go back to a carb. It ends up being a lot of work for very questionable gain.

If you would tell is what your symptoms are and what you've already done, we can probably point you in the direction of a solution using stock parts.

 

That’s more or less what I wanted to know. I would like to keep it stock if I can, but at this point I’m getting a little frustrated 😅. I had posted some of my issues before I’ll let you guys know what I’m dealing with. So far I’ve burned up 4 coils. It will run fine for about 5 minutes and then when you even touch the gas pedal it stutters really bad, after doing that about 5 times it dies with the coil being bad.
So far I’ve replaced the ICM, rotor, and a bad cap. I checked all the plug wires which none of them had strange resistance. I also pulled a couple of spark plugs and they were dark but not worn and had a normal gap, I’m still planning on changing the plugs just in case they were bad.

 

Off the top of my head I think it could be a wiring short or internal short in distributor. Maybe but unlikely a shorted radio filter capacitor...the little capacitor the connects right to the coil, try disconnecting that, should have a gray plastic connector.

 

Forgot to ask, did you pull the codes? you can do this for free with a paperclip if you don't have a reader.

 

Thanks. A few more things to check out really help, I was beginning to run out of ideas. A short in the distributor makes sense, would I have to remove the distributor and take it apart to get to all the wiring?I would have never thought of the radio capacitor, but if that’s it then that should be an easier fix. I was planning on pulling the codes but just haven’t had time yet.

 

Radio cap connects coil directly to ground, so if its half shorted, I can see that causing a problem. I replaced my distributor yesterday, wasn't too bad.

Also, plug gap and wires are #1 cause of eating coils, sometimes things test 'good' even when they're not, usually due to an intermittent failure--needs to hit temp or vibrate just the wrong way.

Again, codes will get us a good starting point.

 

I’ll check into that stuff tomorrow and hopefully will get some codes soon. Thanks again

 

Interested to hear what you find as well. That five minutes per coils is a pretty short life! Actually an extremely short life!
When I ran my factory ignition coil on a full 12v jumper wire I did that for literally two months of daily driving and never had a problem with it. Continued to use it after I figured out where the broken wire was.

Now, that was on an old-school canister coil and those were known for being robust for their time, but they were just like anything else and we're warned not to supply 12v to them for long or they will overheat. I was taking chances, but that story was just to showcase how fast yours are dying if all they're getting is some extra current.
But disconnecting the radio noise suppressor is easy and free. Whenever I've had one fail it just killed the engine and didn't let it start after. Never burned out a coil. But that was always on older vehicles too, with canister coils. Which are not supposed to be as rugged as the e-core coils on these vehicles. And which already get 12v too, and are controlled by the computer. Seems like there's not much to go wrong with this type of system, at least in regards to the coil.

Good luck! Hoping for the quick-n-easy fix after all your frustration.

Paul

 

By the way... What is it exactly that tells you the coils are bad?
Are you testing them afterwards with some method or other? Or just from replacing and having it run afterwards is leading us to that conclusion?

Just wondering if it could be some ancillary fault that "resets" when the coils are changed.
Do you have a link to your other discussion? Have you tried testing/replacing the TFI module (I assume a '93 7.5 has one?) yet?

Thanks. Not really intimately familiar with your particular setup, but throwing things out there to keep it lively!

Paul

 

Wow, I knew I was going through coils fast, but I didn’t realize I was burning through them THAT fast. I test the coil when the truck won’t start with a multimeter, it shows continuity in the positive/negative connections (I think that is the primary winding). And no continuity between either the positive or negative and the output for the distributor (I think the secondary winding). New coils show continuity. Also right after replacing with a new coil it starts right up.

 

Also I already replaced the TFI module, which is what I was calling the ignition control module (ICM).

 

Very odd to be killing coils that fast - they're usually pretty robust. If the distributor and PIP are original, it might be a good idea to replace the PIP as a preventative maintenance measure. It's often recommended to replace the PIP and TFI/ICM together as a failing one can take out the other. And yes, TFI = ICM.