Compression test instructions with pics.

Impr3zy0u · 03-08-2006, 01:44 PM

So i didnt really find any good instructions online on how to do a compression test on a 2002 WRX, so heres a little thing i made to help others that are looking to do this. Once this checks out the next best thing to do is have a leak down test completed.
First things first you want the engine worm when doing the test. I found that the time needed to get everything out of the way and ready to test is plenty enough time for the engine to go from HOT, to worm.
With this method i recommend gloves as the engine will be pretty hot. I left the engine running and got as much work done as i could with it running. Pulled off the passanger side molding to gain access to the fuel pump relay, unbolted the 2 bolts at the battom of the air filter box, loosened the hose clamps, took off the battery tie-down, and pulled the windshield washer resivor.
After that is all done you will want to shut off the car, and go to the passanger side of the car and look for the green plug. This is the fuel pump relay and youll want to un-plug this. Its easier said than done but it will eventually come off. Dont tug on the wires.

After thats pulled, pull the intake box off, pull the batt, and you should already have the windshield resivor off and out of the way. Should look like this, a mess

Next you'll want to pull off the coils. One bolt holds each on, and then a simple clip to unplug them and totally remove them from the engine bay for more room. Keep track which one was where. Im not sure if it matters, but i didnt want to find out the hard way. The drivers side rear one is a PITA, you pretty much have to loosen it with a socket, then do the rest with your hand.
Next youll want to remove all the plugs. Get a spark plug socket with the rubber insert to hold the plugs, helps alot. I would also tape the socket to the extenson. Mine keep falling off the extension in the cylinder.

Plugs and coils removed.

Next screw in the compression testor and crank the engine the same amount of times for each cylinder. I did 6 cranks for each one, also rember to floor the throttle. Pray they come out ok

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Impr3zy0u · 03-08-2006, 01:45 PM

Here are the results for my cylinders. Good luck, boxers are the worst engines to do compression tests on, have fun!11!

Passanger rear

Passanger front

Driver rear

Driver front

150, 150, 150, 150

**Another thing i forgot to mention**
On the passanger side rear cylinder there is the front o2 wire bracket that is attached to the same bolt and the coil, dont forget to put that back on when installing the coil.

dvang · 03-08-2006, 01:48 PM

looks good how many miles are on your car?

Impr3zy0u · 03-08-2006, 01:49 PM

Quote:

Originally Posted by dvang

looks good how many miles are on your car?

64,442

Bundyboyz · 03-08-2006, 03:31 PM

what do you mean by cranking the engine six times???

I'm near 70,000 changed my plugs at 55... they were a bit white so I want to check them again... mine as well do this too I figure.

Impr3zy0u · 03-08-2006, 03:35 PM

you have to crank it over to get a compression reading, i did it 6 times, or till the needle is steady.

_sti_05 · 03-08-2006, 03:54 PM

Is flooring the throttle a must? or can it be done without? what other ways can you stop from the car cranking up beside pulling the fuel pump relay?

Nice write up btw, very useful.

JRSCCivic98 · 03-08-2006, 03:59 PM

Flooring the throttle is nessacery to allow air to be pulled into the cylinders.

_sti_05 · 03-08-2006, 04:01 PM

Oh ok cool, just checking.

Impr3zy0u · 03-08-2006, 04:29 PM

Quote:

Originally Posted by _sti_05

Is flooring the throttle a must? or can it be done without? what other ways can you stop from the car cranking up beside pulling the fuel pump relay?

Nice write up btw, very useful.

What do you mean "stop from the car cranking up"? As in starting? With no plugs, or coils, or fuel, if it starts you have a keeper. BTW between not flooring it and flooring it i noticed like a 5psi difference

_sti_05 · 03-08-2006, 04:34 PM

True, never thought if that. My head is not in the right place today.

Quote:

Originally Posted by Impr3zy0u

What do you mean "stop from the car cranking up"? As in starting? With no plugs, or coils, or fuel, if it starts you have a keeper. BTW between not flooring it and flooring it i noticed like a 5psi difference

jblaine · 03-08-2006, 05:19 PM

Quote:

Originally Posted by _sti_05

True, never thought if that. My head is not in the right place today.

That assumes you remove all coils at once.

When I do mine, I am in the habit (no reason) of doing one cylinder completely at a time (remove coil, remove plug, test, install plug, install coil).

The step after disconnecting the fuel pump relay should always be: Crank the car until the engine stalls. Crank a bit more.

Then remove battery.

It's a safety thing.

Tea cups · 03-08-2006, 06:48 PM

I was under the impression that you needed to pull all plugs before testing to get an accurate reading.

cdvma · 03-08-2006, 06:57 PM

Quote:

Originally Posted by Tea cups

I was under the impression that you needed to pull all plugs before testing to get an accurate reading.

It helps the engine crank over a bit easier, but it shouldn't change the reading any real ammount.

Antyoo · 03-08-2006, 07:03 PM

you could simply pull the EFI fuse

its a lot easier than pulling the fuel pump relay.

also, yes it is best to remove all the coils and spark plugs. make it easier to turn the motor over for the compression test.

jordanscotty · 03-08-2006, 07:05 PM

may i ask where you got the compression tester and for how much?

norexyet · 03-08-2006, 08:32 PM

You dont have to disconnect the coils, just disconnect spark. Its the brown plug next to the green one under the kick panel. You dont have to keep the coils in order just need the plug the wires in correctly. The white connectors go in the front coils the black connectors go in the back coils.

Impr3zy0u · 03-08-2006, 09:02 PM

Quote:

Originally Posted by jordanscotty

may i ask where you got the compression tester and for how much?

Murrys, like $20

overdose · 03-10-2006, 06:04 AM

good, the question of engine health is out of way... hope you inspected those coilpacks closely, there's no good way to verify their condition other than physically or swapping a known good pack with a known misfiring hole, find any vacuum or preturbo leaks?

Impr3zy0u · 03-10-2006, 11:45 AM

I didnt find any leaks and everything looked good with the coils/plugs.

Paul · 03-10-2006, 01:41 PM

when i did mine i couldn't find the fuel pump fuse so i just pull the connectors off the injectors. Is there anything wrong with that?

tasq · 03-10-2006, 01:57 PM

pics are b0rked

-Kevlar- · 03-10-2006, 02:15 PM

wow n00b, you got a sticky and borked your pics.

Bundyboyz · 03-12-2006, 05:54 PM

I've gotta do this later in the week... so the unit is only 20.00 or so

gopsu · 03-12-2006, 07:36 PM

so what's the best way to do this? plugs must be removed or not when performing compression test?

03-08-2006, 01:44 PM	#1
Impr3zy0u Scooby Specialist Member#: 93404 Join Date: Aug 2005 Location: MI Vehicle: 2002 WRX Aspen White	Compression test instructions with pics. So i didnt really find any good instructions online on how to do a compression test on a 2002 WRX, so heres a little thing i made to help others that are looking to do this. Once this checks out the next best thing to do is have a leak down test completed. First things first you want the engine worm when doing the test. I found that the time needed to get everything out of the way and ready to test is plenty enough time for the engine to go from HOT, to worm. With this method i recommend gloves as the engine will be pretty hot. I left the engine running and got as much work done as i could with it running. Pulled off the passanger side molding to gain access to the fuel pump relay, unbolted the 2 bolts at the battom of the air filter box, loosened the hose clamps, took off the battery tie-down, and pulled the windshield washer resivor. After that is all done you will want to shut off the car, and go to the passanger side of the car and look for the green plug. This is the fuel pump relay and youll want to un-plug this. Its easier said than done but it will eventually come off. Dont tug on the wires. After thats pulled, pull the intake box off, pull the batt, and you should already have the windshield resivor off and out of the way. Should look like this, a mess Next you'll want to pull off the coils. One bolt holds each on, and then a simple clip to unplug them and totally remove them from the engine bay for more room. Keep track which one was where. Im not sure if it matters, but i didnt want to find out the hard way. The drivers side rear one is a PITA, you pretty much have to loosen it with a socket, then do the rest with your hand. Next youll want to remove all the plugs. Get a spark plug socket with the rubber insert to hold the plugs, helps alot. I would also tape the socket to the extenson. Mine keep falling off the extension in the cylinder. Plugs and coils removed. Next screw in the compression testor and crank the engine the same amount of times for each cylinder. I did 6 cranks for each one, also rember to floor the throttle. Pray they come out ok * Registered users of the site do not see these ads. Last edited by Impr3zy0u; 03-12-2006 at 10:27 PM.

03-08-2006, 01:45 PM	#2
Impr3zy0u Scooby Specialist Member#: 93404 Join Date: Aug 2005 Location: MI Vehicle: 2002 WRX Aspen White	Here are the results for my cylinders. Good luck, boxers are the worst engines to do compression tests on, have fun!11! Passanger rear Passanger front Driver rear Driver front 150, 150, 150, 150 Another thing i forgot to mention On the passanger side rear cylinder there is the front o2 wire bracket that is attached to the same bolt and the coil, dont forget to put that back on when installing the coil. Last edited by Impr3zy0u; 03-12-2006 at 10:24 PM.

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03-08-2006, 01:48 PM	#3
dvang Scooby Specialist Member#: 84188 Join Date: Mar 2005 Chapter/Region: MWSOC Location: its too cold Vehicle: 05 legacy caravan full of kids now	looks good how many miles are on your car?

03-08-2006, 03:31 PM	#5
Bundyboyz Scooby Specialist Member#: 32764 Join Date: Feb 2003 Chapter/Region: MAIC Vehicle: 2003 WRX with 91K New Motor & Paint WRB	what do you mean by cranking the engine six times??? I'm near 70,000 changed my plugs at 55... they were a bit white so I want to check them again... mine as well do this too I figure.

03-08-2006, 03:35 PM	#6
Impr3zy0u Scooby Specialist Member#: 93404 Join Date: Aug 2005 Location: MI Vehicle: 2002 WRX Aspen White	you have to crank it over to get a compression reading, i did it 6 times, or till the needle is steady.

03-08-2006, 03:54 PM	#7
_sti_05 Scooby Specialist Member#: 72313 Join Date: Oct 2004 Chapter/Region: TXIC Location: Brownsville, Tx Vehicle: 16 STi Black	Is flooring the throttle a must? or can it be done without? what other ways can you stop from the car cranking up beside pulling the fuel pump relay? Nice write up btw, very useful.

03-08-2006, 03:59 PM	#8
JRSCCivic98 Scooby Specialist Member#: 67080 Join Date: Jul 2004	Flooring the throttle is nessacery to allow air to be pulled into the cylinders.

03-08-2006, 04:01 PM	#9
_sti_05 Scooby Specialist Member#: 72313 Join Date: Oct 2004 Chapter/Region: TXIC Location: Brownsville, Tx Vehicle: 16 STi Black	Oh ok cool, just checking.

03-08-2006, 06:48 PM	#13
Tea cups Scooby Specialist Member#: 103136 Join Date: Dec 2005	I was under the impression that you needed to pull all plugs before testing to get an accurate reading.

03-08-2006, 07:03 PM	#15
Antyoo Scooby Newbie Member#: 64161 Join Date: Jun 2004 Location: Santa Clarita Vehicle: 2004 WRX Blue	you could simply pull the EFI fuse its a lot easier than pulling the fuel pump relay. also, yes it is best to remove all the coils and spark plugs. make it easier to turn the motor over for the compression test.

03-08-2006, 07:05 PM	#16
jordanscotty Scooby Newbie Member#: 85931 Join Date: Apr 2005 Location: irvine,ca Vehicle: 05 wrx blue	may i ask where you got the compression tester and for how much?

03-08-2006, 08:32 PM	#17
norexyet Scooby Specialist Member#: 39149 Join Date: Jun 2003 Chapter/Region: Tri-State	You dont have to disconnect the coils, just disconnect spark. Its the brown plug next to the green one under the kick panel. You dont have to keep the coils in order just need the plug the wires in correctly. The white connectors go in the front coils the black connectors go in the back coils.

03-10-2006, 06:04 AM	#19
overdose Scooby Specialist Member#: 46399 Join Date: Oct 2003 Chapter/Region: MWSOC Location: Grand Rapids, MI Vehicle: 0000 Knows nothing, about nothing.	good, the question of engine health is out of way... hope you inspected those coilpacks closely, there's no good way to verify their condition other than physically or swapping a known good pack with a known misfiring hole, find any vacuum or preturbo leaks?

03-10-2006, 11:45 AM	#20
Impr3zy0u Scooby Specialist Member#: 93404 Join Date: Aug 2005 Location: MI Vehicle: 2002 WRX Aspen White	I didnt find any leaks and everything looked good with the coils/plugs.

03-10-2006, 01:41 PM	#21
Paul Scooby Guru Member#: 56203 Join Date: Feb 2004 Chapter/Region: Tri-State Location: south nj Vehicle: 00 RSTI Coupe Twin Scroll 2.5XTR EJ207	when i did mine i couldn't find the fuel pump fuse so i just pull the connectors off the injectors. Is there anything wrong with that?

03-10-2006, 01:57 PM	#22
tasq Scooby Specialist Member#: 62362 Join Date: May 2004 Chapter/Region: RMIC Location: Denver, CO Vehicle: 2005 wrx CGM	pics are b0rked

03-10-2006, 02:15 PM	#23
-Kevlar- Scooby Specialist Member#: 82378 Join Date: Mar 2005 Chapter/Region: South East Vehicle: <--- Hot Donuts Now	wow n00b, you got a sticky and borked your pics.

03-12-2006, 05:54 PM	#24
Bundyboyz Scooby Specialist Member#: 32764 Join Date: Feb 2003 Chapter/Region: MAIC Vehicle: 2003 WRX with 91K New Motor & Paint WRB	I've gotta do this later in the week... so the unit is only 20.00 or so

03-12-2006, 07:36 PM	#25
gopsu Scooby Specialist Member#: 96448 Join Date: Sep 2005 Chapter/Region: Tri-State Location: NY Vehicle: 02 WRX VF34	so what's the best way to do this? plugs must be removed or not when performing compression test?