# DIY: How to do a Compression Test



## Ronisonce (Apr 5, 2004)

*Compression Test directly from Bentley Manual.*
*1.* Release locking pins for engine cover by turning 90 degrees. Remove the cover completely.
*2.* Warm up engine until it is a minimum of 30 degrees Celsius (60 degrees F) and switch ignition off.
*3.* Disconnect 4 pin harness connectors from all ignition coils and 
remove ignition coils (Place them in a way that you know which ones are for each cylinder). If you have an AWD engine code unbolt the coils from the head and remove the vacuum reservoir (canister).. If you have an AWW or AWP engine code just remove the coils.
*4.* Use compressed air to clear area around spark plugs. Remove all spark plugs and lay aside in an order that you remember which one goes to each cylinder.
*5.* Remove fuse *#32* for voltage supply to injectors (in car)
*6.* Fit compression tester into spark plug hole.
*7.* Have a helper - Depress clutch pedal fully, Put transmission in either park or neutral, Depress the accelerator pedal to floor, Crank engine over with starter motor. Crank a minimum of 4 to 5 revolutions.
*8.* Record readings from each cylinder in gauge and repeat procedure for each cylinder.
*9.* Compare readings to these specifications.* New Cylinders* (145-203 psi) *Wear limit* (102 psi) *Maximum difference between cylinders* 44 psi 
*10.* When all cylinders have been checked, reinstall spark plugs and ignition coils, connect harness connectors for coils and reinstall fuse *#32*. Reinstall fuse panel.
*NOTES* Cranking engine with ignition system disabled and components disconnected will cause Diagnostic trouble codes (DTC's) to be stored in engine management system memory. You must clear these codes.
*Tightening Torques* Spark plug to cylinder head - 22 ft/lbs 
*Tightening Torques* Ignition coil to cylinder head (If bolt down coils) - 7 ft/lbs.
Enjoy !


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## theswoleguy (Jan 25, 2006)

*Re: DIY: How to do a Compression Test (Ronisonce)*

http://****************.com/smile/emthup.gif 
now someone explain the other little things you can do while compression testing. IE: teaspoon of oil in the cylinder to check for bad rings


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## Ronisonce (Apr 5, 2004)

*Re: DIY: How to do a Compression Test (theswoleguy)*

never heard of that "trick". Anyone care to shed some light on that ?


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## Tongster (May 31, 2002)

*Re: DIY: How to do a Compression Test (Ronisonce)*

I heard that if you have low compression in a cylinder, then the method of putting some oil through the spark plug hole will allow the compression psi to be higher (the oil being a gap filler) as an indicator of bad rings. It doesn't matter what grade oil (same as what your using is probably best) but the amount you put in I'm not sure about.


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## 20thAEGti1009 (Jan 28, 2005)

just use a cap full of oil.. and that trick works wonders for sealing worn ring


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## Ronisonce (Apr 5, 2004)

*Re: (20thAEGti1009)*

Hopefully this will be a sticky


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## matimus (Nov 10, 2003)

*Re: (Ronisonce)*

Great info! Thanks
bump to make a sticky!


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## crazyass713 (Dec 28, 2006)

*Re: DIY: How to do a Compression Test (Tongster)*


_Quote, originally posted by *Tongster* »_I heard that if you have low compression in a cylinder, then the method of putting some oil through the spark plug hole will allow the compression psi to be higher (the oil being a gap filler) as an indicator of bad rings. It doesn't matter what grade oil (same as what your using is probably best) but the amount you put in I'm not sure about.

a cap full of oil in the spark plug hole will suffice for amount... if your compression jumps more than 10psi during a wet compression test, i would be somewhat concerned


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## Issam Abed (Feb 12, 2004)

*Re: DIY: How to do a Compression Test (theswoleguy)*


_Quote, originally posted by *theswoleguy* »_IE: teaspoon of oil in the cylinder to check for bad rings

Emphasis on teaspoon.Growing up a job came into the work shop because the owner wanted to do his own compression testing,suffice to say he hydrolocked the motor.


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## theswoleguy (Jan 25, 2006)

basically enough to just cover the top of the piston


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## Ronisonce (Apr 5, 2004)

*Re: (theswoleguy)*

LOL, I guess that customer must have put a quart in each spark plug hole


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## DuNa (Aug 2, 2011)

lol!


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## jberg001 (Aug 5, 2009)

*ATC Engine Code*



> If you have an AWD engine code unbolt the coils from the head and remove the vacuum reservoir (canister).. If you have an AWW or AWP engine code just remove the coils.


Anyone know where the ATC engine code falls in the above statement? Remove the vacuum reservoir or not?


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