leak down and compression affecting idle?

[nagemong]

I have a rough idle (~1000rpm), especially when the engine is cold, but much longer than a minute (like others have said on this board). The only time it is smoother is when the RPMs are higher ( >1200 ), or when its warm enough that the oil is hot. But even then it will have its moments of roughness that can be directly correlated with a sudden lean mixture (by looking at an air/fuel meter).

I recently did a leak down and compression test and want to know what people think about how they all relate to each other, and the severity of the leaks.

cylinder       1     2    3    4
-----------------------------------------
leak down%   20 40   5   20 ( all through the rings )
compression 120 115 125 125

I believe the reason that the leak down is so bad is because the engine was sitting for an unknown amount of time with the spark plug holes open. A tradgedy I know.

Thanks in advance for any thoughts.

[DannoXYZ]

Nah, most likely it's your idle-stabilizer or air-temp sensor in the AFM. While those leak-down figures are ugly, they'd cause uneven running all the time. Was the leakdown test and compression done on a cold engien? Do you get a smokey exhaust when the engine's warmed up?

[nagemong]

Hmm, I recently took out the idle-stabilizer and tested it and oiled it, as well as sealing a bunch of air leaks in the surrounding tube connections. Fixing those air leaks made the air fuel ratio much better while idling, and made for a much improved and smoother take off from idle.

I tested the air temp sensor in the AFM with a multi meter when it wasn't running and it seemed pretty good, although that may be suspect. I will try and put the oscilliscope on it while it is idling and see if there is any jumps in voltage. It should be as constant as the outside air temp is right?

Leak down was on a pretty warm engine and compression was probably some what warm if I remember correctly.

I haven't noticed any smokey exhaust when the engine is warm, a bit when it is cold, but that could just be some water vapor.

I was thinking that any "uneven running" was just getting masked by the faster rpms.

Thanks for your reply.
Good to see a fellow Santa Barbarian on here