Contour Enthusiasts Group Archives Forums Modifications Duratec Maintenance stu-stu-stuttering in primarys not in secondaries

Originally posted by blu_fuz:

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sooo, my '95 mtx v6 tour is missfiring in the primarys pretty bad... but not in the secondaries. she probably needs some updating. This is what I plan to do:

-plugs
-plug wires
-fuel injector cleaner
-fuel filter
-ignition coil

anything else I should do???

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This is a classic "bad ignition wires" symptom.
The problem is bad in the lower rpm when you give it gas but clears up as they rpms climb.
This is because the coil duty cycle gets shorter as rpm increases since there is less time between cylinder firing. Each coil fires in wastespark method once per revolution.
When the duty cycle is long the coil gets oversaturated; as the wires go bad their resistance changes and this culminates in ignition spikes that can sort of fire the coil too early and then when it tries to fire it can't.
All those things are good to do, probably an intake cleaning as well. Change the order to Wires first and recheck the plug gap.
Save the fuel injector cleaner for last and it never hurts to do the fuel filter. However, logically if it was a fuel issue it would crap out more as rpm climbed since there is a higher fuel demand at higher rpm. Right?