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Old 10-11-2018, 02:51 PM   #1
SMITHDALTON34
 
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Default Tachometer issue leads to misfire

Hello fellow Nissan gurus, I have an issue here and I'm scratching my head on where to start. I have a 1986 D21 4x4 Z24i with 108xxx OG miles. About 3 - 4 months ago I noticed the tach jump around occasionally (1 or 2x per week). It has since gotten worse and yesterday only functioned 10 minutes out of the 1.5 hour I was driving. The tach WILL WORK if I press the throttle 2/3 or 3/4 of the way to the floor 80% of the time...very aggravating...

I have also noticed that if the tach stops working completely the truck will only rev till 2500 - 2800 rpm and then cuts out/sounds like two-step if you mash it to the floor. When it is in this stage I can only run 50-60 mph MAX depending on conditions.

I have replaced: Cap, Rotor, Plugs, Wires, Timing set (guides, tensioner, chain, sprockets), Oil Pump, Water pump, Head Gasket, Intake Gasket, Exhaust Gasket, removed EGR and all vacuum crap (plugged and sealed all ports), 304 stainless header, no cat muffler only.

I do have a timing light and currently have timing set @ 5 deg BTDC per badge under hood.

Any help is appreciated! thanks
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Old 10-11-2018, 03:05 PM   #2
OldGreyBeast
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Sounds like your coil may be going bad.
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Old 10-11-2018, 08:29 PM   #3
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I'm going to replace them both since they are older anyways and see what happens. I am wondering if there is a "crimp" or plug or something somewhere in the wiring harness that could be loose and needing soldered. I'll see what 2 new coils does! Thanks!
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Old 10-11-2018, 09:40 PM   #4
cadillacdude1975
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the tach resistor is tied up in the coil wire harness around the driver headlight area. i have a thread on it in here somewhere with pics of the resistor.
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Old 10-12-2018, 02:32 PM   #5
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might check the "power resistor" on both coils..
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