I have an 89 5.0 Bronco that I have had for about 4.5 years. I have been having a problem for the last four years that I think I have finally figured out. The truck runs fine except when I go on vacation in the desert (mojave, ca) in the summer. The truck will sputter and die when I am driving with a load in the heat.

From what I read, it is the TFI module that is causing the problem when it gets too hot. The TFI is only 3.5 years old (The original one died on me a month or two after I bought the truck). Did I just get a defective one or are all of them going to do that to me? I spend a lot of time in the desert and do not see late 80's and early 90's f-150 /broncos littering the side of the road when it is hot so I hope I can fix the problem.

Since it is a design flaw with the TFI module, is there a way around it? The recall information about the problem identified the magic temperature to be 257 degrees before it starts causing the misfires that will shut the engine down. I made sure that my cooling system is operating at peak efficiency but it still happened. Is there a way to keep the engine bay cooler so the TFI module will not heat up so high? Also what about moving the TFI Module away from the engine to a different part of the engine bay? In researching this problem I saw other Ford sites where people did this.

I really want to keep my truck but if I can't remedy this problem I will have to get rid of it. I can't keep having my truck stall on me everytime I go on vacation. It sucks being stranding in 105 temp on the side of the road.

Thanks for any help.

 

Did you liberally apply the heat sink compound when you put on the new one? I live in florida not desert hot (Its a WET HEAT here!!) I have my truck for 8 years I replaced the module after I got that letter and I super glued a heat sink onto the back of the module just to be safe (maybe overkill) And I put a hose from the cold air area of the radiator brace to direct cold air onto my distributor and throttle body to keep it cool!!
Maybe it helps maybe not but it makes me feel better! I know its working because there's a dark spot on the throttle body where the air hits it (dust buildup) that I wipe off every now and then because it looks weird! Try that out and see if it helps!

 

By the heat sink compound do you me the heat resistant grease? If so I used it but maybe did not do a good enough job. Where did you get a heat sink to glue on it? I am so frustrated with this that I wouldn't mind overkill at this point.

If I can't solve the problem is there any aftermarket ignition systems that might work.

 

I have a bunch from when I used to make amplifiers and other electrical doodads!
We have a electrical surplus down here (Skycraft surplus) They have a web site just measure what you need and give them a call they are super cheap and they got good deals on stainless hardware and diamond plate too. Or you could grab the next computer you see in someones garbage and take the proccessor heatsink off it some have a fan that connects on it, You could hook that up so during low speeds you could switch it on and keep it cool. Another trick you can use that is good for diagnosing heat related electrical failures is to get a can of keyboard duster and turn it upside down so the liquid freon comes out. If it starts acting up give it a few quick blasts .5 to 1 second and see if that cures it, that might even get you home!!

 

Blue Beast

You said that you ran a hose to bring in cool air from outside the engine bay. What size hose did you run? All I can find around me is 3/4 inch.

Thanks

 

Pull continuous memory codes first. I don't know if your ignition is the same as mine. I have another thread going with intermittent dying. I have replaced everything and it finally died without restarting. I finally used the Haynes diagnostics, bought a 12v test light and used my multimeter. Everyone agrees it is a bad ground wire in the harness. I finally followed the test procedure exactly and kept looking at the wiring diagram and the light in my head finallly lit. Now I know what 12 inches of harness to inspect when I get time and check the tan-yel wire. In your case, remove, check and clean the connectors of the ground strap ribbon between the engine and chassis first. Then take a $6 test light with you, multimeter and Haynes. If it dies stick the light probe on the Tack (passenger) side of the coil while trying to start it. If the light comes on but does not blink there is trouble in the primary circuit like mine. Hayes goes into detail from there.