Moin, I had a compression diagram made today (Zafira A 1.6 CNG, Built 06/04, 70tkm), as this one (as reported here) apparently has problems with the valve seats (too soft material). In this test the following values have come out : Cylinder 1 : 11.5 bar Cylinder 2 : 13 bar Cylinder 3 : 12 bar Cylinder 4 : 9 bar Do you hold this scatter for normal (especially Zyl.4) ? Thanks for your help, Gruss, Michael