How To Test Engine Compression (1.6L)

Testing the engine compression on your 1.6L Honda Civic (Civic del Sol) is a pretty easy and simple affair, since the spark plugs are right on top of the engine. This tutorial will walk you through the entire process in a step-by-step fashion and will also help you interpret your test results.

Here are the contents of this article at a quick glance:

  1. Symptoms Of Low Or No Engine Compression.
  2. The ‘Dry’ Engine Compression Test.
  3. ‘Wet’ Engine Compression Test.
  4. Which Compression Tester Should I Buy?
  5. Related Test Articles.

Symptoms Of Low Or No Engine Compression

An engine compression test will help you troubleshoot the root cause of:

  1. A misfire condition (engine miss, rough idle condition).
    1. Usually caused by very low compression in one cylinder or...
    2. Uneven engine compression that varies more than 15% across all 4 cylinders.
  2. A Cranks but Does Not Start condition.
    1. Usually caused by no compression on 2 or all 4 cylinders.

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

Having low or no engine compression in one cylinder on your 1.6L Honda Civic will cause your engine to miss at idle and you'll definitely feel there's something wrong when you accelerate the vehicle.

When this happens (low or no compression on just one cylinder) and your Honda vehicle is OBD II equipped (1996+), you'll see one of the following misfire diagnostic trouble 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.

If your Honda Civic (Civic del Sol) is NOT OBD II equipped, you won't have any codes lighting up the check engine light, but you'll definitely feel a rough idle condition.

The next common scenario is having low or no engine compression on two ADJACENT engine cylinders... and your Honda won't start. It'll Crank but Not Start. This usually indicates that the head gasket has burned between the two cylinders.

If a blown head gasket is a concern... take a look at this tutorial I've written: How To Test For A Blown Head Gasket (Honda 1.6L).

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 belt.
    3. Engine thru' 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 1.6L Honda Civic.

The ‘Dry’ Engine Compression Test

How To Test Engine Compression (Honda 1.6L)

If you don't have an engine compression test... 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

    The engine's temperature is an important consideration before you start the engine compression test. What I mean is this... the engine can not be completely cold and yet it can't be hot. It should be warmed up.

    NOTE: If your Civic doesn't start, then don't worry about the engine being warm.

  2. 2

    Disconnect all of the fuel injectors and the distributor from their electrical connectors. This will prevent the fuel injection and spark firing while cranking the engine. This will also prevent damage to the ignition coil.

  3. 3

    Now, 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!

  4. 4

    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.

  5. 5

    OK, when you're ready, have a helper crank up your Honda 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 4 cylinders.

Let's interpret the results of your compression test

CASE 1: Low or no compression in 2 or ALL cylinders.. This tells you you've got serious engine mechanical problems.

The most common issues would be:

  1. Blown head gasket. For further testing, go to: How To Test For A Blown Head Gasket (Honda 1.6L).
  2. Broken timing belt. For further testing, go to: How To Test For A Broken Timing Belt (1.6L Honda Civic).
  3. Engine threw a rod.

CASE 2: Low or no compression in one cylinder.. This compression result confirms the cylinder misfire trouble code (and that that cylinder is ‘dead’).

It's important that you make sure that this low compression value is truly out of specification. How? By doing the math and seeing if it's below 15% the highest compression value you got from all 4 cylinders. Here's how you do that:

  1. Multiply the highest compression value that you recorded by .15.
    1. So, let's say that cylinder #4 gave you the highest reading of 170 PSI. Well 170 X .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 Civic 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 .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.