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Originally Posted by jwakil

My 81 930 runs very well I think, although must admit I haven't driven another one to compare power. It pulls strong, and idles steady. It smokes sometimes on startup, but that I regard as normal. The oil usage is a little high (probably a little more than a quart per 600 miles, but those miles are all mostly city miles so hard to judge). Anyway, I ran a leak down test and found all cylinders less than 10% leakage, except for #1 which was showing something like 80% leakage!. The #1 cylinder spark plug hole is a ***** to access and ensure proper tightening of the leak down tool, but I ran the test twice and got similar results so have to think the test was done properly. So my question is, how can I have such poor performance in one cylinder, and still have the car running well? If the valves are leaking and need adjustment for that cylinder, would the car still be running ok? What else can explain this?

From the airplane world, listen to the intake while pressurized, then the exhaust, then the crankcase breather line. If it's the crankcase breather line hissing, drive for 10 hours and retest. If it's either of the valves, sorry, motor work is in your near future. The reason it's running well is due to the huffer(turbo), but it ain't right, find out why, or drive it till it blows.