Hey - looking for some input on this:

my GSR's been running pretty rough for the last few weeks (rough idle; sounds a little like it's missing when I accelerate under light-medium load) and I'm getting a bit sick of it so I figured I'd do something. I've got a SUN engine analyzer at work so just for kicks I hooked up the inductive pickup and watched the spark voltage on each cylinder.

Cylinder 1 was around 12-15 kV and cylinders 2-4 were each anywhere between like 7 and 10 kV. I'm not sure what the voltage is supposed to be, but the fact that it's irregular between plugs makes me think something's wrong.

 

Have you recently spray washed your motor?

 

No sir

 

Is it missing at idle too? Can you isolate it to individual cylinders?

 

I can't trace the miss; it seems to idle without missing but under moderate load I can hear it start to sound really irregular... I know my dis. cap and rotor are well past due for replacement but I'm also suspecting I could have a leaking head gasket messing with my compression or worse on a couple cylinders (engine temp seems to randomly 'spike' to high and then drop down to low again - never stays hot but I've got a huge fluidyne on there).

 

Check for missfires by hooking up a timing light to a plug wire and shoot the flashes at your hood and see if that cylinder is firing consistantly. You can also throttle the engine a little while your doing this to see if it happens at throttle.