chicomacattack

So i took it to a shop qnd now there trying to tell me that my tps is whats causing low compression im pretty bs ure there full of it

chicomacattack

Thanks i also believe its valves. But the valves must really be messes upbif its causing a misfire and low compression right? I will do a wet test when i get the car back. Im probably not gonna pay them anything theee retarded

jkelley

Depends on your definition of "really messed up." They can be slightly bent and are not seating properly. If they're not seating properly then they won't hold pressure which is also why you would get a misfire. This would be considered really messed up and would need to be fixed. However, they could just be out of adjustment and once you get them adjusted they will seat fine and hold compression... but then our could also have burned valves which is also not good

chicomacattack

We did a wet test it turned out to be piston rings.

jkelley

So you're saying you got good compression with the wet test? If that's the case, I would double-check that cylinder after running it (if the car runs) and make sure that the compression is still bad when the oil is out. Is there a chance the mech didn't have that cylinder at TDC when he did it originally? That would cause low compression.

jeffbrig

We're talking a compression test, not leakdown. You put the pressure gauge on the cylinder, and turn over the engine to record the pressure generated. It's not a static test with the piston sitting at TDC.

It's not unusual for an s2000 to show more wear in cylinder 4. Do a search and you'll find quite a handful of cases with cylinder scoring in #4. That one seems to be the weak spot for lubrication in this motor.

Slowcrash_101

Well it is the furthest point from the oil pump, not to mention it's the first cylinder that gets coolant from the radiator, not to mention it's the part of the motor that is most enclosed by the chassis, hence least amount of radiation to the outside air. The fact it's the first cylinder to receive coolant means the combustion chamber has the coolest liquid passing through the water jackets, which leads to the highest condensation of burned exhaust gases, because it's also the first cylinder to get EGR. This could explain why cylinder 4 always has the dirtiest pistons, and spark plugs.

jkelley

LOL duh... Not sure why I was thinking leak down lol my bad. I thought a wet test was only useful with a leak down though?