'88 TC. Yesterday I put in a new TFI, PIP, cap and rotor, all Motorcraft. Today the car has a major miss that comes and goes. When it comes, it's as bad as a miss can get. Pretty much as bad as if you were turning the key on and off. I changed all this stuff because the car had cut out on me a few times last week. THIS miss it NEVER had. A coincidence that now something else is going? Would a coil do this intermittent miss? The plugs were changed a few weeks ago and the wires are about 2 years and probably about 40k old, also Motorcraft. Any ideas out there? Thanks... Chuck
explain when it does it. all the time or when in boost. install the original cap and rotor and see if that fixes the problem if not install the new ones and put the old tfi back on. problem goes away then it was the tfi if it is still there then it is the PIP.
From what I gather it never did it before the change of parts right?
I had a miss that I thought was a turbo or IC problem turned out after I replaced my TFI PIP and installed a n MSD coil it went away. spark was probably weak and was blowing out when the new turbo and IC went in. my plugs are gapped at .030.
What Brian said, when does it do it/not do it?
Pull the codes.
Any chance a plug wire got damaged/not seated well?
likely something you messed with. maybe a loose connection on the TFI/PIP?
-J0N
When I did all this yesterday, it ran fine. Today it had a bad stumble when I first took it out that went away when it warmed up. Tonight, ran great for about 30 mins., then was missing like crazy, then ok, then missing... It doesn't do it at any particular time or speed or boost or temp. When it has the miss, it will miss at any kind of acceleration, hard or easy. I was thinking about changing back the cap and then the TFI, but all this started happening tonight like 8:00. I checked the wires 10x, pushed them on, moved them around, whatever I could do. I opened the hood at least 10x. Would 2 year old wires or a coil do this? When it doesn't have the miss, it runs great. VERY inconsistent.
The three TFI terminals on the distributor can rust inside. The TFI connector can have loose terminals not making good contact with the pins. Coils could be intermittent or shorted internally but they usually just die. Probably not wires unless you damageed them when installing the new cap.
Well, I just went out and changed the cap and rotor back to the old ones. Same thing. Great for about 1/2 hour then the miss is back. I had another thought... I have an ACCEL TFI that I bought for another car and never used. The Ford TFI didn't come with the heat sink compound, so I opened the ACCEL one and used what came with IT. It said "silicone" on the tube. It wasn't the white chalky pasty stuff that was on the original and felt like regular silicone. It's about 25* out there and the TFI didn't even feel warm. Could this silicone have something to do with it? Radio shack gets like $7.50 for a little shot syringe of the heat sink compound, would that make a difference? It's the only thing I can think of. A little too late, too cold and too dark to do the TFI now, but would it be a good idea to remove it and use the radio shack stuff? Has anyone ever gotten a bad Motorcraft TFI or PIP out of the box?
Ive never had one but doesnt mean it cant happen.
Swap the TFI's and see if it happens since everything else checked out good then it seems like the TFI is your problem. take it off put the old one back on. If it runs good take the TFI back b/c it doesnt work. When you get the next one put the heatsink grease on it and be done with it.
Being in the electronics field, I've used both clear silicone and white silicone "heat grease". The clear always seemed to work OK, but the white stuff is definitly better. I don't believe this could cause your problem however.
My gut tells me plug wires. Can't really put my finger on it but that's the next thing I'd try, especially if yours are "standard" motorcraft and are two years old. Of course that's "shotgunning" and is NOT really the way to do things. Take it with several grains of salt.
Just my 3¢ worth.
My first reaction was the same as Joe's. I'm not saying the plug wires are the problem but with 40K miles on them I would replace them to eliminate a "potential" contributor