Bizarre problem has me stumped. F-350 460

[Mr_Bill]

So I have a 1995 F-350 crew cab dually with a 460 with an auto tranny. Rig has around 160k miles on it. Up until 3 days ago ran awesome and has never had any major issues. No rebuilds or mods aside from the cat was removed around 6 years ago and a true dual exhaust was added.

Symptoms: At idle the engine is smooth however the RPM gauge (not the engine) jumps around fluctuating +/-500 rpms. Under normal acceleration the rig drives perfectly no issues. However under heavy acceleration the rpm gauge shoots clear over 6k and I get what sounds to be missing, it acts as if there is a rev limiter on the engine.

I am assuming this is all related to the rpm gauge not working correctly and giving false information to the system. Problem is I dont know where to start to begin diagnosing the problem. After some looking it seems that the rpm gauge is connected to the distributer.

Anyone have any thoughts as to what could be the cause of this issue?


Thank you,
Bill

 

[fatherdoug]

Could be as simple as a loose connection on the tachometer, or on the coil?

 

[Mr_Bill]

I may have to kick myself if this is it. So thinking maybe some of the corrosion from all the cap and rotors that have been replaced numerous times over the years might be interfering with a sensor in the distributer I pop the cap and blow it out with the compressor. After this I go and start the rig and since the hood is still open I hear a odd little crackle/pop like a jumping spark. So keep it running and wouldnt luck have it anytime i looked away I would hear it. I isolated it to around the coil area. Looking at the coil wire I notice I can see some clean area where its slipped out off the boot a little. So I shut the rig down and jiggle the coil wire only to have it pop right out of the boot and the end is kinda crusty so think its been bad for sometime and im just now noticing.

So off to the parts store to get a coil wire will update when I return and replace it to see if this fixes the problem.



***UPDATE***

Went and bought a new set of wires and it fixed the problems. No RPM flutter, no high speed sputter and seems to have gotten some power back. Thank you fatherdoug!!