I have a 99 blazer with a random misfire code. It is for cylinders 2, 4, and 6. The numbers of misses got worse from cylinder 2 to 6 I have repalced the plugs, wires, rotor and capand the misfire count seemed to get worse for the 4 cylinder instead of the 6 cylnider. (The wires are in the correct postion). The mifires are only detected when the engine is at idle. Anything above 1000 rpm and it appears to be fine. There is also a code for the o2 sensor for low voltage.

 

first check your primary coil wire. the design is prone to breaking the wire.

 

I have replaced the coil wire or do you mean the wires going into the coil?

 

well, start pulling our plugs ans see if they are fouled. the gap might not be correct, and check the cap and rotor. sometimes if they are not lined up perfectly, they will cause problems.

 

Ok i pulled the new plugs are they were starting to get a sooty film over them so I changed the O2 sensor from the left side to thte right side, now the 1,3,and 5 cylinder are having the miss fire and the others are fine. So I guess I need to get new sensors Thanks for your help

 

Figures I am a day late.
Glad you found the problem.