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View Full Version : HOW TO: Compression Test



trinydex
10-08-2007, 12:19 PM
Tools:
Compression Tester (can get from Autozone ect.)
Socket Wrench
Socket Extender
10mm socket (for spark plug cover)
13/16 Spark Plug Socket
Torque Wrench


From the shop manual:

COMPRESSION PRESSURE CHECK M1111002600421

1. Before inspection, check that the engine oil, starter and
battery are normal. Also, set the vehicle to the following
conditions:

? Engine coolant temperature: 80 − 95?C (176 − 203?F)
? Lights, and all accessories: OFF
? Transaxle: Neutral

2. Disconnect the spark plug cables.

3. Remove all of the spark plugs.

4. Disconnect the crankshaft position sensor connector (located next to oil cap, a triangular connector).
NOTE: Doing this will prevent the engine control module
from carrying out ignition and fuel injection.

WARNING
Keep your distance from the spark plug hole when
cranking. Oil, fuel, etc., may spray out from the spark
plug hole and may cause serious injury.

5. Cover the spark plug holes with a shop towel etc. Crank the
engine for a few seconds to clear debris from a round the
spark plug holes. After the engine has been cranked, check
for foreign material adhering to the shop towel.

6. Install the compression gauge to one of the spark plug
holes.

7. Crank the engine with the throttle valve fully open and
measure the compression pressure.
Standard value (at engine speed of 250 r/min): 1,128
kPa (163 psi)
Minimum limit (at engine speed of 250 r/min): 951 kPa
(138 psi)

8. Measure the compression pressure for all the cylinders, and
check that the pressure differences of the cylinders are
below the limit.
Limit: 98 kPa (14 psi)

9. If there is a cylinder with compression or a compression
difference that is outside the limit, pour a small amount of
engine oil through the spark plug hole, and repeat the
operations in steps 6 to 8.

(1) If the compression increases after oil is added, the cause
of the malfunction is a worn or damaged piston ring
and/or cylinder inner surface.

(2) If the compression does not rise after oil is added, the
cause is a burnt or defective valve seat, or pressure is
leaking from the gasket.

10.Connect the crankshaft position sensor connector.

11.Install the spark plugs (Torque: 18 ft/lb) and spark plug cables.

12.Use the scan tool (or disconnect battery for 1 min) to erase the diagnostic trouble codes.

NOTE: This will erase the diagnostic trouble code resulting
from the crankshaft position sensor connector being discon-
nected.

http://www.socalevo.net/gallery/albums/userpics/10991/mURI_temp_c23cad75.jpg

Matz
01-18-2008, 11:19 PM
I just ran a compression test today, hoping to do a how to for NCE. Turns out that this was already here, and I guess I didn't do mine exactly right. I hadn't considered disabling fuel injection before conducting the test. I also didn't know it was important to have the TB fully open, but I guess it makes sense to eliminate airflow variation from cylinder to cylinder.

Anyhow, here are some additional pictures.

stuff to remove:
http://www.initialdproject.com/evo8/HowToDoCompressionTest/step1.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/step2.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/step3.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/step4.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/step5.jpg

moving from cylinder #1 to cylinder #4:

cylinder 1:
http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder1_connection.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder1_reading.jpg

cylinder 2:

http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder2_connection.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder2_reading.jpg

cylinder 3:
http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder3_connection.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder3_reading.jpg

cylinder 4:
http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder4_connection.jpg

http://www.initialdproject.com/evo8/HowToDoCompressionTest/cylinder4_reading.jpg

Here's what the gauge looks like when you crank the engine:

Right click and select Save As... (http://www.initialdproject.com/evo8/HowToDoCompressionTest/compression_test.avi)

Compression is a bit lower in the first two cylinders, but still okay IMO.

DoggDicker
01-18-2008, 11:24 PM
I did mine with the tb closed and then open, it varied one or two PSI...

DD

redevil9mr
01-19-2008, 10:06 PM
That is very good info. I always thought that compression test was hard to do but after reading this tech article, I manage to learn how to do the compression test. Thanks guy. :D

Matz
01-20-2008, 12:57 AM
Yeah, I guess it is nice that triny is cross posting on multiple forums. I don't have to log into evom and SCE to find stuff now. :)

I didn't see one for the leakdown test, so I might post a how to on that next.