TunerLexx

I was wondering what the compression should be for a 93 sc400 4.0L. I'm only getting about 10-11 MPG and I'm pretty sure I should get damn near 20. And, no, it's not like I romp the hell outta the car either; I rarely need to exceed 2k RPM to shift...more like 1800 or so depending on the gear. I do a general mix of highway and city driving...moreso shorter distances. Where I'm confused is that I run alot of gas just sitting in place...also, there's no heavy gas scent and I run no engine codes (but the light 'does' work). The car doesn't run rough or have any difficulty at all, purrs like a kitten. The point of this story is that a friend I explained this to told me to check the compression (even though I think the car would run noticabley different if that was the issue).

The only guaranteed issue I know of is that both valve cover gaskets are bad and I wind up losing between 1-2 quarts by the time i change oil (4-5k at most on synthetic only). I've done a tune up on the car changing the plugs, wires, cleaning the fuel system and 'thoroughly' cleaning the intake and throttle body with intake manifold by disassembling. The engine is clean as hell and I've maintained the ballz outta it. Any advice please? Thanks in advance ^^.