Misfire update, 1989 Computer bad.

[The Miracle]

The Ranger will run pretty well with the Spout connector undone, but misfires grossly when the spout signal is present. I ran new wires for the pip signal and spout signal from the TFI to the computer. In doing this I am able to backprobe it while its running.

I would think that if it runs well with no spout, the TFI is doing ok. With spout out, the computer is sending out a return frequency the same as the pip input frequency. Both increase frequency similarly when the pedal is pressed down a bit.

The last time this happened, I replaced the computer with a used unit and it ran great for about a year, after swapping the TFI with a cheapy. It did run great with the cheapy. Opens up a can of worms though, as in if its done that again, what keeps killing my computers?

I suppose my question is, should I venture to replace my TFI unit first? Or just bite it and get yet another computer.

Third option I guess would be to leave spout undone and just drive it around. Mostly using it for dump runs and in town hauling if need be.

 

[The Miracle]

Welp Yep Nope
Borrowed an oscilliscope, PIP signal going to computer is a nice even pulse wave, Spark output coming from computer is pure shredded wheat. I guess it killed another one.

 

[alwaysFlOoReD]

Thanks for the update.

 

[Jazzer]

Great testing-not the answer you might have wanted but you got it right.

-Jazzer

 

[The Miracle]

Great testing-not the answer you might have wanted but you got it right.

-Jazzer

Maybe jumping off the old beast is killing the computer. I only run it a few months out of the year. Of course, putting out for a new computer is out of the question, there is one company that does but its very expensive. Its times like this I like Dodge and Chevy as they kept recycling their old stuff. In my case, my engine and trans are aok, but the electrical system is not. The "remanufactured" computer I bought was a silver spray painted obviously used unit. I love this nasty truck, but hate how pigeonholed my options are for improving it.