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Old 11-17-2021, 06:57 PM   #25
alordofchaos
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Join Date: Jan 2009
Location: Central MI
Posts: 13,313
 

2002 SC2
1998 SL2
Default Re: specifics on compression testing, P0301

^ ^ ^
Yeah, we;re still kinda guessing here because we don't have numbers we can be confident in
Quote:
Originally Posted by lanxer57 View Post
Does that apply to any engine? Even fuel injected ones?
Yes, the fuel supply doesn't matter. As a matter of fact, you should have pulled the PCM-B fuse out, as mentioned in the links I provided upthread. That shuts off the fuel injectors - which both prevents fuel from washing down the oil from the cylinder walls and throwing off your compression reading - by temporarily sealing any leaks.

You are taking a fixed amount of air at ambient pressure in the cylinder, compressing it, and seeing the pressure after compressed. A low compression number means air is leaking out, either past compression rings or valves (damaged/worn valve or valve seat). At higher altitude, that same amount contains less air to compress.

Quote:
Originally Posted by OldNuc
Nominal compression for a high mileage good condition DOHC is 190-220psi and SOHC is 175-205psi.
Using the 80% adjustment fetchhitfido provided, the SOHC range should be 140-164 psi. Or 149-174 if you use your 85%

Quote:
Do not screw it into the head past the point the sealing o-ring just contacts the head. Do not overtighten as it will leak.
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I'm not worthy to grovel in the shadow of Signmaster's wisdom

11/2016 red 2002 5 spd SC2 151k DD
12/2008 eBay silver 1998 SL2 5 spd 102k, now 201k+ miles
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