Check the compression and manifold vacuum (compare the readings to this chart
The compression needs to be at least 135 psi and the lowest cylinder should be at least 70% of the highest. If one or more cylinders are low do a "wet" compression test by pouring a couple tablespoons of oil into the cylinder and testing again. If the compression rises the rings are worn, if not the valves are leaking...
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq