VoxMan

Ok, so my '95 runner was acting up, rough idle, nasty smoke (kinda grey in color smelled a bit like plastic, hurt to breathe it). Took a look under the hood and found that the air hose from intake to TB was half way disconnected. Put it back on and started it up. Seemed to fix the rough idle and exhaust went back to the typical early morning condesation type cloud. But me being my paranoid self, I decided to do a comp test to set my mind at ease (just did top end rebuild ~8k miles ago) and here's what I got:
1. 185 2. 180
3. 180 4. 180
5. 240 6. 185

I'm totally stumped as to why I would have overly high compression in that cylinder. Any ideas? Thx.

PS. Engine has 130033 Miles on it

SEAIRESCUE

Carbon?.....My father acquired a Buick from a little old lady. When it got warm, there was a knock in the engine. Decided to run several cups of water through the carburetor and needless to say, I mosquito fogged the whole neighborhood. White carbon everywhere. After that, knock disappeared and motor smoothed out and spark knocking went away. So, carbon can collect in cylinders. Its possible #5 is passing a little oil and carbon is much worse in that cylinder. Did you hold the throttle wide open for each test? I would do the Seafoam treatment through the vacuum line to the brake booster following the instructions on the can. Basically, slowly choke the engine to a stall with first half of can. Let it sit for 30 minutes, start engine and finish pouring other half in and stall again. Let set 30 minutes. Attach vacuum line and go for a drive to clean it out. Some say to put a second can in gas tank to clean the injectors.

My $0.02

mt_goat

I doubt carbon built up too bad in only 8k miles. How did that plug look?

VoxMan

Plug was a bit dirty, some oily residue on it. No worse than any of the others though.

notanymore

wont a bad oil ring cause high compression?