How To Test Engine Compression (Toyota 1.8L)

Testing the engine compression of your Toyota 1.8L equipped vehicle is a pretty easy and simple affair, since the spark plugs are right on top of the engine.

In this tutorial, I'll walk you through the entire process in a step-by-step fashion and help you interpret your compression test results.

En Español You can find this tutorial in Spanish here: Cómo Probar La Compresión Del Motor (1.8L Toyota Corolla) (at: autotecnico-online.com).

Symptoms Of Low Or No Engine Compression

Depending on the compression problem or problems your Toyota is having, the two most common symptoms your Toyota will experience will either be a rough idle (misfire) condition or a cranks but does not start condition.

Engine compression problems usually fall into specific categories:

  1. Uneven compression across all four cylinders.
  2. No compression in all four cylinders.

I'll go into some detail about these two in the next couple of paragraphs...

Uneven compression across all four cylinders is usually caused by one or two cylinders that have low compression.

The end result of this low compression, in one or two cylinders, is a misfire condition that will cause your engine to miss at idle.

Here are some more specific symptoms you'll see:

  1. Misfire Codes:
    1. P0300: Random Cylinder Misfire.
    2. P0301: Cylinder #1 Misfire.
    3. P0302: Cylinder #2 Misfire.
    4. P0303: Cylinder #3 Misfire.
    5. P0304: Cylinder #4 Misfire.
  2. Rough idle.
  3. Lack of power.
  4. Blue smoke coming out of the tailpipe at idle and/or when accelerating (this is engine oil burning in the cylinders).

No Compression in all 4 cylinders and your Toyota won't start. It'll crank but not start. This usually indicates that your Toyota's engine is blown.

When you have a situation where you have no compression on ALL 4 cylinders, you'll see:

  1. The engine cranks very fast and this fast cranking speed is very noticeable.
  2. The ignition system is sparking all 4 spark plugs, so you know it's not an ignition system problem/issue.
  3. The fuel injectors spray fuel.
    1. You can confirm this with a noid light test.
    2. Also, you can confirm this, although indirectly, by removing the spark plugs and checking to see if they are fuel soaked (fuel fouled).
  4. Fuel pump is working and providing pressure.
  5. The most common causes of this scenario, are:
    1. Blown head gasket.
    2. Broken timing chain.
    3. Engine threw a rod.

OK, having covered the most common scenarios of low compression and no compression, let's get testing to see if this is the case on your 1.8L Toyota.

The ‘Dry’ Engine Compression Test

How To Test Engine Compression (Toyota 1.8L)

If you don't have an engine compression tester, you can buy one from your local autoparts store or, if you have an AutoZone or O'Reilly Auto Parts store nearby, you can rent one from them (they'll rent it for free, after you leave them a cash deposit for the tool, which you'll get back once you return it).

If you need help deciding where to buy one or which one to buy, take a look at my recommendations: Which Compression Tester Should I Buy?

IMPORTANT: You'll be working around a cranking engine, so you have to be careful and stay alert at all times. Think safety all of the time!

This is what you'll need to do:

  1. 1

    Disconnect all of the fuel injectors. This will prevent fuel from being injected into the cylinders as you crank the engine.

  2. 2

    Remove the 4 COP ignition coils and remove all four spark plugs. As your taking them out, be careful and don't drop any of them on the floor, or you could cause the spark plug's ceramic insulator to break, and this will cause a misfire!

  3. 3

    Thread the engine compression gauge into the spark plug hole for the number 1 engine cylinder (this is the spark plug hole closest to the drive belt). Hand tighten the compression gauge only! Do not use any type of tool to get it tight.

  4. 4

    Have a helper crank the engine, when the test is set up, as you observe the needle on the compression tester's gauge. Once the needle on the gauge stops climbing, have him or her stop cranking the engine.

    Record this compression reading on a piece of paper. Include the number of the cylinder this reading belongs to. Now repeat steps 1 thru' 6 on the other 3 cylinders.

  5. 5

    Write down the compression test result and the cylinder the test result belongs to.

    Repeat the test in the next 3 cylinders.

Let's examine your test results:

CASE 1: Low or no compression in 2 or ALL cylinders. This isn't good and indicates that your Toyota has serious engine mechanical problems.

The most common issues would be:

  1. Blown head gasket.
    1. To further test this, I recommend the following tutorial: How To Test For A Blown Head Gasket (Toyota 1.8L).
  2. Broken timing chain.
  3. Engine threw a rod.

CASE 2: Low or no compression in one or two cylinders. With this type of test result, we now need to a simple math calculation to find out if this test result is within normal specs or not.

This is how you can find out:

  1. Grab a calculator and multiply the highest compression reading that you recorded by 0.15.
    1. So, let's say that cylinder #4 gave you the highest reading of 170 PSI. Well 170 X 0.15 gives you 26 (25.5 rounded off).
  2. Now, the next step is to subtract 26 from 170, which gives us 144 PSI.
  3. So then, 144 PSI is the lowest possible compression reading that any one of the rest of the engine cylinders can have. Any compression reading below this and that engine cylinder will misfire.

Now, so that this calculation can make more sense to you, let's say that my Toyota Corolla gave me the following compression readings:

  1. Cylinder #1 175 PSI.
  2. Cylinder #2 160 PSI.
  3. Cylinder #3 165 PSI.
  4. Cylinder #4 30 PSI.

The next step is to do the math: 175 x 0.15= 26, 175-26= 149. So, now I know that cylinder #4 is the one causing the misfire!!

Now that you've found the cylinder with the low compression, the next step is to see if this low compression is caused by worn cylinder head valves or worn piston rings. For this test, go to: ‘Wet’ Engine Compression Test.

Chevrolet Vehicles:

  • Prizm 1.8L
    • 1998, 1999, 2000, 2001, 2002

Pontiac Vehicles:

  • Vibe 1.8L
    • 2003, 2004, 2005, 2006, 2007, 2008

Toyota Vehicles:

  • Celica 1.8L
    • 2000, 2001, 2002, 2003, 2004, 2005

Toyota Vehicles:

  • Corolla 1.8L
    • 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
  • Matrix 1.8L
    • 2003, 2004, 2005, 2006, 2007, 2008
  • MR2 Spyder 1.8L
    • 2000, 2001, 2002, 2003, 2004, 2005