Ugh, electrical gremlin is killy my ignition coil.


May 2, 2005
Here is what I know. Something in my TFI is frying ignition coils after about 50 miles whenever I put a new coil in.

I took a multimeter out to the car and did the trick where I put the negative lead on the negative battery terminal and then touch the positive lead to the block. Well, I get between .003-.008 volts on the block and a bunch of ppl over on the corral are telling me I should not see ANY voltage on the block at all. I'm going to change out my grounding strap tomorrow with a big 4 gauge unit and add another to the passenger's side. I'm also going to clean the **** out of all the connecting points.

Also, my stepfather in law is a senior ASE certified mechanic and his opinion is that under 1 volt on the block is not going to hurt anything and that the only thing that would fry a coil is a bad stator in the dizzy feeding back into it.

So basically I wanted to see if anyone else ever ran into a problem like this or had any advice.

I already replaced the TFI, the afermarket ignition box is good(problem happened with an old box too), plug wires checkout, rotor and cap are new... Can't think of anything else.

So I guess I'll replace the stator and ground the **** out of the motor and go from there? I really NEED to get this fixed asap since I have to take this thing through inspection in 12 days.

Thanks in advance guys!
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Your potential-drop test results sound fine to me personally.

Remember that the coil receives constant key-on 12 volts and the EEC (via the TFI) modulates ground to the coil. CCD TFI's watch the falling edge of the PIP signal and 'shut off' the coil (this was done to help coils last longer) but something like that should not be your issue.

If the car runs ok till the coil craps out, I'd be wondering about coil failures. A multiple spark box can stress a coil out a good bit more than a stock ignition.
Yeah but the ignition box was on there fine for 2 years not to mention that every tom dick and harry runs a box these days. This should not be an issue...

And otherwise a stock ignition should not have an issue either. So what we have here is a situation where parts are seemingly breaking but the components used in the system are assumed to not be an issue. The logic is recursively flawed IMHO.

Good luck.
Yeah but I replaced the box with a Crane unit and the issue persisted... Problem is also that I NEED an ignition box to keep running the A3M computer via the PIH harness. I suppose I can bypass it and just run under 3,000 rpm for 50 miles up and down the highway and see what happens.
None of us even knew you had a 94-95 with a PIH swap. There are more variables for you. If you have other related stuff on the car, post it up so folks can consider the situation as a whole.

How are the coils frying? I would do primary and secondary resistance tests on a new coil and then again after the coil fries (or atleast compare your fried ones to the listed manufacturer specs).
What are the symptoms when the coil fails?
Are you sure you dont have another component that is croaking and the down time while replacing the coil is allowing the primary issue to abate? For example, PIPs are known for getting wonky when hot and working again once cooled off.

If you put a test light across the electrical connector on the coil and try to start the car, the test light should flash. If it does but you have no spark egressing the coil, the coil is likely bad. But if you are missing that flashing test light, running down the system before the coil is in order.

Good luck.
I know its the coil because when I replace the coil the car starts right back up but I don't know what is frying the coil. I'm going to try replacing the PIP and see what happens. My ase senior mechanic stepfather in-law is convinced that's the problem as he says its the only thing that would be frying the coils like this car is.
If the PIP was going wonky, you'd probably be seeing drivability issues since the PIP is responsible for injector timing. The TFI module is what takes the PIP signal (after it's generated and then again after the EEC cleans it up and modifies it) and ultimately grounds the coil.

Just something to consider if it still acts up after replacing the PIP.

Good luck.
Well I changed the TFI module out when the problem first started happening and it didn't help matters. I've basically replaced everything in the ignition including the aftermarket box with another one, the TFI module, the coil, the wires, the plugs, the rotor/cap etc... The only thing left is to throw on some big 4 gauge grounding cables and change the PIP.

I can't think of anything else except to re-install the J4J1 computer, bypass the ignition box and see if that works which will be my next step if the PIP and grounds don't fix this problem. The car ran fine for years with the PIH and an ignition box though... no idea why this problem just started happening out of the blue.