Hi,

I check the Bentley Service Manual, page 032-1, which also states "minimum" compresion pressure as 9 bar/128 psi for your model year. It also states your compresion ration is 7.5:1, 131 hp at 5400 rpm, 155 ft-lbs of torque at 3750 rpm and CIS fuel injection. Non turbo norms are 170 psi.

I'm not a turbo person, though I am a CIS person. You might want to post your question on turbobricks,

http://forums.turbobricks.com/forumdisplay.php?f=12

In my non-turbo opinion, your compression is too low. Have you checked for vacuum leaks? Check vacuum pressure (normal 18-22 inches of mercury). It takes 20 seconds to do and $20 for the gauge. Also, do a wet test, but only add 1 cc of oil. I got a false high reading when I added 10 cc of oil to my spark plug hole last week. My 1980 242 DL non-turbo with nearly 260k miles has the following compression readings (for comparison purposes): #1 164, #2 168, #3 167, #4 169.

This is a long shot, but check for air leaks in the intake manifold, exhaust manifold, fuel injectors, and spark plug holes. I had a damaged spark plug thread in my 1989 245 DL. Compression was only 149-150 psi in that cylinder, whereas all other cylinders were 164-168 psi. I heard a hiss when I ran the compression test, so I knew the spark plug thread was still damaged. I used a tap and got 9 of 11 turns into the spark plug thread. Compression went up to 164 psi!