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How to test your compression

39606 Views 28 Replies 25 Participants Last post by  jasonc624
I have been seeing alot of questions about compression and how to test, so here is a writeup i did.

Compression Test by Smaay

1. Open hood

2. Remove engine plastics with 5mm Allen Wrench.

3. Plastics removed

4. Reach behind engine to unplug power steering sensor

5. Remove the four 10mm bolts holding coils.

6. Unplug coils

7. Remove the two 10mm nuts holding wiring harness.

8. Lift wiring harness out of the way.

9. Pull all four coils.

Coils removed exposing sparkplugs

9.5 unplug the 4 injectors so they dont squirt.

10. Using 5/8 spark plug socket and suitable extension (6-8 in.) remove and inspect sparkplugs. They should be a copper color like pictured.

Image of compression tester purchased at Autozone/Pep Boys/Kragen/Napa/etc.

11. Screw compression tester into cylinder 1 hand tight.

12. Hold down gas and clutch at the same time, crank engine over about 6 times, until needle stops jumping on compression tester

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13. Record results.

14. Release air pressure from tester and repeat for each cylinder.

Straight from the Toyota Manual (BGB)

Compression pressure:
1ZZ-FE 1,500 kPa (15.3 kgf/cm2, 218 psi)
2ZZ-GE 1,400 kPa (14.3 kgf/cm2, 203 psi) or more
Minimum pressure:
1ZZ-FE 1,000 kPa (10.2 kgf/cm2, 145 psi)
2ZZ-GE 1,000 kPa (10.2 kgf/cm2, 145 psi)
Difference between each cylinder:
1ZZ-FE 100 kPa (1.0 kgf/cm2, 15 psi) or less
2ZZ-GE 110 kPa (1.1 kgf/cm2, 16 psi) or less

15. After test complete, put car back together in reverse order.

16. DONE! Have a beer to celebrate good results, or sulk in sorrows.

edit: this will throw a CEL for misfires. there is a fuse you can pull to prevent it but im not sure which one it is. but just unhook your negative terminal on the battery for 5 minutes and it will reset the CEL. Also the car might have a hard time starting, dont worry, just give it a few more cranks. It will start
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Nice write up.!
This is awesome. Thanks a lot!
Nice How-to. You dont really need to remove the power steering sensor plug and move the coil harness out of the way.

Also you forgot to remove the injector plugs.
very nice write up.

what should the psi be for 8:1?
Bro - you forgot to tell them to unplug the injectors so they don't wash their cylinder walls and wind up blowing fuel out the plug holes.

You also forgot to mention that they will have 4 igniter codes stored in the ECU after this that will need to be erased

Otherwise nice writeup
You can get a compression tester at walmart also. It's usually cheaper. That's where I got mine. If they sell it at kragen's, etc. Check walmart. It will probably be 25-35% cheaper. Not just compression tester, but other automotive parts. Mobil 1 oil synthetic for 5 quarts is only $20 bucks, cheaper then costco.

And yes very important part is to unplug the fuel system. If there is an easy accessible fuse, that would be the easiest way, if not, unplug them from the harness.

You should also mention you can do a wet test. If compression is low, or 0, put a capful of oil in the cylinder which is low and try again. See if it gets you a bit more compression. If not you got some bent valves, if so, prob. the rings.
hey i cant think of everything. Added the information
How much for the compression tester?
And good job with the write up
JoManGT-S said:
How much for the compression tester?
And good job with the write up
$20 at AutoZone
210?? is that the optimal for the 2zz?? (just curious, would expect somewhere in the 240 range)
He showed me this in person and had the info for compression out of the Toyota bible while he was working on his motor on an engine stand Multitasker I tell you. You are god! Jeff is the man! Thanks for the awesome write up makes life easier!
1. What is the point of removinge the power steering plug? Just wan't to know.
2. If you start the car in WOT (throttle fully open) you do not need to unplug the injector, they will stay shut! In fact this is the way you should start the car if the engine is "drown" for some reason.
nice job smaay, I had seen this done on an accord before but never knew the whole process myself. I'm glad you took the time to do a writeup.

Is there a certain size fitting that the compression gauge has to have in order to fit down in there right and get a proper reading? Or will any 5/8 compression gauge do the job?
210? isnt that really high? i thought 2zz's were supposed to compress at like 170? Isnt it the atmospheric pressure times the amount of compression, in our case 14.4*12.5=180...isnt that what is is supposed to be?
220, 218, 225, 220 ... thats higher above normal. is that bad?
180 is supposed to be tops.
i got about 220 all around, is that right about where it should be?
infox said:
i got about 220 all around, is that right about where it should be?
Higher compression than stock is often caused by carbon buildup around the valve. Normally you have to take action when the pressure is below the minimum spec or when their is too much difference between cylindre...

But hey... I used my Celica GT for about two years with cylindre 1 at 135PSI and the other at 185PSI. The only drawback was taking an eternity going at 190km/hre... But my problem was only a bent valve so who cares..
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