Compression testing question

[coolrider2112]

Ok I am doing a compression test and my results for all cylinders are getting around 120-125psi I have been doing the test by myself since the gauge on the compression tester should hold. I decided to have my wife to crank the car while I watch the the gauge on the tester. I noticed the needle in the gauge bounces to 150-155 and then goes down to 120-125psi, I have tighten the hose in the spark plug hole as tight as possible, does this mean I have a leak on my tester somewhere or what? (It does really bounces to 150-155 psi on like the first few cranking revolutions and then it just goes to 120-125 psi. Thank you for any replies on this.

 

[WES_393]

Yeah I's say your gauge on the tester is malfunctioning. It should hold the highest number it reads and only drop back down maybe 1 or 2 psi before it catches the needle.

 

[myfirstgsx]

if all cylinders do the same thing then the tester is fine it will always be higher when your turning it over

 

[codeofdastreets]

Did you remove all 4 spark plugs,make sure car is not getting fuel(take out the mpi fuze), and give it full throttle while cranking it over about 6-7 times? Compression should hold on a stock 1g 150 unless your rings are warn, if you see it dropping from 150 that most likely means your tester is broken.

 

[Calan]

Another vote for a bad tester or seal in the cylinder.

Try putting a little oil on the connector seal and see if it changes the readings.

 

[Leo_99]

i would get a better tester and do a leak down test. My gauge is apparently not that great. I did a test and only got 120 on a brand new build. All 4 matched so i wasnt that worried. I did a leak down test to be sure and it was less the 2%.