my tac jumped a couple of days then peged itself. loose wire? where does the thing hook up?

Could be the senser on the tranny side is gone. Check that first.

my dads Rx7 1st gen, rpm gauge was spottering then it would go out work go out.

we changed the coil's but that did NOTHING.

finnaly we learned it was the Igniter so we bought another one sure enough it works now!!!!!!!!!!!!!!!!!! ($$$im just a kid take advice from somone that has experience.)

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Nick the Greek

I know for sure on the 5.2 mpi engines, the tach is driven off the PCM (POWER TRAIN CONTROL MODULE). and from the schematics, it looks like the 4 cyl and v-6 are like that also, but the prints don't specifically call out the tach output.

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05 2500 Laramie QC 4wd In MoltenRed
delivered-4/30/05, 4/30/08- 76,400 miles
5.7L with g-56 Mercedes 6 spd trans 3.73 LSD,
17" polished aluminum wheels, O/R tire option
Tow & Security pkg, Factory Nerfs
Sprayed Bed Liner, Century Cap