Cause of high compression in a cylinder
 

Okay. So what would cause one cylinder to be extremely high as opposed to the others... I'm looking at this USDM GSR motor and all of the cylinders were at 210 but one happened to jump extremely quickly to 270. Was it just improperly done? Or is there something wrong there?

Thanks, Shaun

Re: Cause of high compression in a cylinder (HondaBullSQ)
 

Test again and see if you get similar results.

Re: Cause of high compression in a cylinder (HondaBullSQ)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HondaBullSQ &raquo;</TD></TR><TR><TD CLASS="quote">Okay. So what would cause one cylinder to be extremely high as opposed to the others... I'm looking at this USDM GSR motor and all of the cylinders were at 210 but one happened to jump extremely quickly to 270. Was it just improperly done? Or is there something wrong there?

Thanks, Shaun</TD></TR></TABLE>

Thats high for a GSR... I'd say do it again. Are you doing the test with the ECU fuse out, and holding the pedal at WOT?

Re: Cause of high compression in a cylinder (LSVTEC 91 Civic)
 

I am guessing that you did the test incorrectly. Try again.

Re: Cause of high compression in a cylinder (maxspeedhonda)
 

well.. the car was a wrecked 1995 GSR that the guy bought and he's selling me the whole swap for cheap. All it'll need is the passenger axle (it got pulled out of the boot upon impact). He never received the key for it so he had to do the test without directly using the ignition inside the car (not sure how it's actually hooked up to do this).

He had said it registered 200 across each cylinder before I had gotten there. He's a trustworthy guy so I'm not worried about it. Wasn't sure if there was something that would cause the cylinder to jump like that.

Re: Cause of high compression in a cylinder (HondaBullSQ)
 

valve adjustment out of spec for that cylinder...

Re: Cause of high compression in a cylinder (PyroProblem)
 

I don't see misadjusted valves would do anything but bring numbers down for that particular cylinder. A cylinder with carbon build up would definitely spike compression numbers. Perhaps the valve seal or guide on that cylinder allowed oil to be pulled into that cylinder or that cylinder was suffering from incomplete combustion/missfiring , etc.

Re: Cause of high compression in a cylinder (bonestockls)
 

That cylinder could have a lof of carbon build up.

Re: Cause of high compression in a cylinder (CovertFI)
 

Like all I could think of would be that the carbon did build up. I didn't think it would make the compression that high and/or make the compression tester rise so quickly. I think the motor might be out of the car right now so how hard is it to do a compression test then???

If it's sat for a while, water or oil could have seeped into the cylinder and displaced the air, causing the compression #'s to be much higher.

Pull the plugs and turn it over to see if it clears out any oil or water.