91 ranger dies when warm

[Javve]

I have a 91 ranger with a 2.9L

The truck was running rough for quite a long time. One day it lost all power and died. It would not start at all. I took the TIF (Ignition Control Module) in to O'Reilly auto parts. They tested it 3 times in a row to make sure it would not pass the first time then start failing. It passed all three times. I did a resistance check on the Ignition Coil. It was out of tolerance (5.9K Ohms instead of a range of 6.5K to 11K) when measured from the negative side to the coil. Positive side to Negative side was within tolerance.

I replaced the coil then started checking for spark at each wire. Plug #6 was not getting spark. Did a resistance check on the wire, it was open. I borrowed a plug wire from another vehicle, and the plug gets spark. So now it will start up when cold, but dies when warm. Normally I would suspect the ICM but that has already been tested. Mine is not remotely mounted, it is on the back side of the distributor. Cleaned it up and put new thermal compound on it when I put it back.

 

[IMenriched]

check the ignition relay and grounds

 

[Javve]

If it is the ignition relay would it still get spark? I forgot to mention that when it dies it still has spark.

Edit: Where is the relay located? I have to admit I have never known of an ignition relay.

 

[holyford86]

there is no such thing as an ignition relay, there is a EEC relay which controlls the computer and a fuel pump relay that controls the fuel pumps. The symptoms that you describe seem like classic TFI heat failure. minus the fact that you have spark. Pull codes and see what you get.

 

[Javve]

Will do. I did check the TFI (I referred to it as a TIF) oops.

 

[holyford86]

there is a common problem with tfi modules where they will work perfectly when the engine is cold but once the engine warms up they don't work right.

 

[Javve]

Thanks for that. At least I can have it out in 10 minutes! I will have to look at replacing it. Now the question is do the generic ones usually have problems? I may have to fork out the $100 for a quality one and know that it should work. I think I'll replace the cap/rotor and wires at the same time since the wires have to come off anyway to get the cap out. That would give me the opportunity to make sure all the connections inside the cap are clean and corrosion free.

Going to be a bit before I get the parts. I will keep everyone posted for those that may be having similar issues.

 

[holyford86]

you don't have to remove the cap to get the tfi mod off the back of the distributor, it's two bolts and then you pull it down

 

[Javve]

I understand that. I have had it off before to get it tested, but I want to take a look at the contacts inside to make sure there isn't anything going on in there.

 

[UnderMedikated]

I'm on my 3rd TFI in under 50K. I've had this one 3 years so crossing my fingers. If you take them out they will most likely test good. You usually need to heat them up to test them. My truck always started after several minutes of letting it cool down. This was enough to limp home.