How to do a Compression test?
12-22-2002, 11:23 PM
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How to do a Compression test?
hey guys, I want to know. I'm going to Pep Boys tomorrow and getting the gauge. Also how does this differ from a leak down test. I want to have a clue whats going on before she goes to 7 psi on Hondata 
Thanks
P.S. Sorry for the noob question, but I want to get my hands dirty!
Thanks
P.S. Sorry for the noob question, but I want to get my hands dirty!
12-22-2002, 11:32 PM
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Re: How to do a Compression test? (FredoSP)
Compression test is actually way easier than a leak down test. First, get the engine up to operating temperature. Second, remove all four spark plugs. Third, either unplug all four fuel injectors or the distributor (injectors will not fire without a cam signal). You don't want raw fuel being injected and blown out of the spark plug holes. Fourth, install compression guage on cylinder one. Depress gas pedal all the way to the floor and crank the engine. I do it until the needle stops moving, but some do it for a set number of cranks. Rinse, lather, repeat. That's it!
Tyler
Tyler
12-23-2002, 08:15 AM
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Re: How to do a Compression test? (Charlie Moua)
15-24.99
Trust pep boys, discount or advanced auto parts .... this is a very simple tool... they all sell fairly reliable compression testers...
Trust pep boys, discount or advanced auto parts .... this is a very simple tool... they all sell fairly reliable compression testers...
12-23-2002, 08:47 AM
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Re: How to do a Compression test? (Tyler H)
i'd let the engine cool down for at least 5-10 minutes, you dont want to strip the threads. also you can take out the 15 amp (i think its 15amp, blue right on the corner)pgm fi fuse.
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01-11-2003, 05:52 PM
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Re: How to do a Compression test? (Tyler H)
Depress gas pedal all the way to the floor and crank the engine. I do it until the needle stops moving, but some do it for a set number of cranks. Rinse, lather, repeat. That's it!
Tyler
Tyler
I have never done this and thinking about testing my GSR motor when it comes in and I get it installed. Thanks for any input!!
01-11-2003, 06:34 PM
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Re: How to do a Compression test? (Hybrid93Hatch)
Do you hold it to the floor until the RPM's get close to red-line???
04-12-2005, 04:20 PM
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Re: (turbodohcsi)
i wouldnt really think the other 3 spark plugs matter that much... since your only worried about the cylinder with the tester on it
04-12-2005, 05:06 PM
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Re: How to do a Compression test? (FredoSP)
Dont unplug fuel injectors, rather have someone hold the throttle wide open as the computer will go into clear flood mode so it will not inject fuel, plus it will make sure it sucks in the air it should.
If you have fuel dump into the cylinders that is like doing a wet test and will not tell you if your rings are bad. (depending how bad they are)
If you have fuel dump into the cylinders that is like doing a wet test and will not tell you if your rings are bad. (depending how bad they are)
04-12-2005, 07:45 PM
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Re: How to do a Compression test? (N20civicB18)
what was that? if you hold the throttle down it wont tell you your true compression or am i reading that wrong?
04-12-2005, 07:47 PM
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Re: How to do a Compression test? (PA MATT)
in order to due a proper "dry" compression test... unplug the dizzy and pull the injector clips. hook up the compression tester and have a buddy hold the car at wot, turn the car over a few times until the compression gauge needle stops moving.
if you dont hold the car at wot, the numbers wil be wrong. because the car will suffer from pumping losses
if you dont hold the car at wot, the numbers wil be wrong. because the car will suffer from pumping losses
04-12-2005, 08:04 PM
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Re: How to do a Compression test? (wantboost)
ive always just unplugged the ecu fuse and then done it at wot, this is the wrong way of doing it?
04-12-2005, 08:14 PM
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Re: How to do a Compression test? (PA MATT)
well, if the ecu isnt getting power... then the car shouldnt be getting fuel, which means the test would be performed dry... so i guess its all the same, one just requires less effort than the other
04-12-2005, 08:21 PM
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Re: How to do a Compression test? (wantboost)
Yup ECU fuse is the fastest easiest way to kill spark and fuel. I have done lots of compression tests with the throttle plate closed and never really had any weird or low readings. I dont think the motor moves all that much air in 7 cranks or however many you are doing it to. But do as I say not as I do 
and keep the pedal floored while cranking. And makes sure all the spark plugs are out and the battery has a strong charge or is on a charger
and keep the pedal floored while cranking. And makes sure all the spark plugs are out and the battery has a strong charge or is on a charger
04-13-2005, 07:58 AM
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Re: How to do a Compression test? (FredoSP)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FredoSP »</TD></TR><TR><TD CLASS="quote">Also how does this differ from a leak down test.</TD></TR></TABLE>
With a leakdown test, you bring one cylinder to TDC on the compression stroke and leave it there. You pull the spark plug and insert the tester. The tester will usually have two gauges - one for setting the input pressure (typically 100psi) and the other reads pressure lost. Because you're using 100psi input, a loss of 3psi will be equal to a 3% leakdown loss.
With a leakdown test, you bring one cylinder to TDC on the compression stroke and leave it there. You pull the spark plug and insert the tester. The tester will usually have two gauges - one for setting the input pressure (typically 100psi) and the other reads pressure lost. Because you're using 100psi input, a loss of 3psi will be equal to a 3% leakdown loss.
04-13-2005, 08:39 AM
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Re: How to do a Compression test? (EE_Chris)
lol guys this thread is OLDDDDDDDDD, lol my noob days.
anyways if someone wants I can provide a video for a compression test and leakdown, just let me know and I can help u out.
anyways if someone wants I can provide a video for a compression test and leakdown, just let me know and I can help u out.
