Expert: Robert Summers - 12/3/2007

Question
This Chev CMFI Engine as of last week after a short trip exhibits a constant miss at idle, at startup and warm and thruout runup and I have checked the ignition, replaced plugs and wiring less than a year ago. I need a new muffler, but doubt that is the problem. It had been having an idle problem before the constant miss developed. I am suspicious that something has happened to one of the cylinders, have not checked compression, awfully hard to get to.  I would like to know if there is a simple test such as removing plug wires from rotor one by one and what to observe.  Don't seem to have any excess exhaust, but do need a new muffler.

Answer
Hi Marv... yes you can remove wires one at a time an see if you notice a change...if you pull one and engine does not miss that would be the bad one...check that wire or plug by switching with one of the others and see if miss moves to that cyl... if it does it is that plug or wire. if not check compression in the bad cyl... hope this helps