Cause of high compression in a cylinder

Honda Bull · 12-09-2004, 05:47 AM

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

t0p_sh0tta · 12-09-2004, 06:17 AM

Test again and see if you get similar results.

LSVTEC 91 Civic · 12-09-2004, 06:17 AM

Quote:

Originally Posted by HondaBullSQ

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

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?

maxspeedhonda · 12-09-2004, 07:47 AM

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

Honda Bull · 12-09-2004, 05:19 PM

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.

PyroProblem · 12-09-2004, 05:43 PM

valve adjustment out of spec for that cylinder...

bonestockls · 12-09-2004, 07:44 PM

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.

CovertFI · 12-10-2004, 06:39 AM

That cylinder could have a lof of carbon build up.

Honda Bull · 12-10-2004, 07:47 AM

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???

LudeyKrus · 12-10-2004, 11:02 AM

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.

12-09-2004, 05:47 AM	#1
Honda Bull Honda-Tech Member Garage is empty, add now Join Date: Nov 2004 Location: 40.201N, 77.189W, PA Posts: 4,662 iTrader Rating: (0)	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 __________________ w w w . i n n o v a t i v e - m o t o r w o r k s . c o m SURJE.motorsports :: EH2 Hatch :: 10.98 @ 129 mph @ "The Beaver"

12-09-2004, 06:17 AM	#2
t0p_sh0tta Honda-Tech Member 2006 Mazda Mazda3 Join Date: Jun 2002 Location: Connecticut Posts: 5,742 iTrader Rating: (0)	Re: Cause of high compression in a cylinder (HondaBullSQ) Test again and see if you get similar results.

12-09-2004, 07:47 AM	#4
maxspeedhonda Member Garage is empty, add now Join Date: Mar 2004 Location: Jensen Beach, FL, 34997 Posts: 1,118 iTrader Rating: (0)	Re: Cause of high compression in a cylinder (LSVTEC 91 Civic) I am guessing that you did the test incorrectly. Try again.

12-09-2004, 05:19 PM	#5
Honda Bull Honda-Tech Member Garage is empty, add now Join Date: Nov 2004 Location: 40.201N, 77.189W, PA Posts: 4,662 iTrader Rating: (0)	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. __________________ w w w . i n n o v a t i v e - m o t o r w o r k s . c o m SURJE.motorsports :: EH2 Hatch :: 10.98 @ 129 mph @ "The Beaver"

12-09-2004, 05:43 PM	#6
PyroProblem Honda-Tech Member 1998 Honda Civic My Garage Join Date: Aug 2004 Location: Atlanta and Florida Posts: 3,003 iTrader Rating: (0)	Re: Cause of high compression in a cylinder (HondaBullSQ) valve adjustment out of spec for that cylinder... __________________ 98 Civic B16b. (92x85 build on hold until 2014) 07 Trailblazer SS (stock 400 hp LS2) 97 Eclipse GST (undergoing surgery)

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12-09-2004, 07:44 PM	#7
bonestockls Garage is empty, add now Join Date: Aug 2004 Location: mn Posts: 54 iTrader Rating: (0)	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.

12-10-2004, 06:39 AM	#8
CovertFI Garage is empty, add now Join Date: Mar 2002 Location: lafayette, la, usa Posts: 2,018 iTrader Rating: (0)	Re: Cause of high compression in a cylinder (bonestockls) That cylinder could have a lof of carbon build up. __________________ Honda-Tech Fitness Challenge member since day 1

12-10-2004, 07:47 AM	#9
Honda Bull Honda-Tech Member Garage is empty, add now Join Date: Nov 2004 Location: 40.201N, 77.189W, PA Posts: 4,662 iTrader Rating: (0)	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??? __________________ w w w . i n n o v a t i v e - m o t o r w o r k s . c o m SURJE.motorsports :: EH2 Hatch :: 10.98 @ 129 mph @ "The Beaver"

12-10-2004, 11:02 AM	#10
LudeyKrus Member Garage is empty, add now Join Date: Oct 2002 Location: Flowery Branch, Ga Posts: 4,768 iTrader Rating: (0)	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. __________________ 1992 Prelude w/ H23-VTEC...handbuilt by me / 1991 MR2 Turbo 1982 Suzuki GS450 - the Rat/Cafe / 1978 Suzuki GS750 - Cafe Racer in Progress / 1977 Harley Sportster - the Chopper

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Cause of high compression in a cylinder