Testing the engine compression, and more importantly knowing how to interpret the results of an engine compression test, is one of the most important diagnostic tools that you need to have in your tool box of know-how. This article will walk you thru' the compression test done on Honda 2.2L and 2.3L 4 cylinder equipped vehicles.
Why do an engine compression test? Because sometimes you run into a rough idle or misfire condition (and if your vehicle is ODB II equipped you'll probably see one of the following misfire diagnostic trouble codes: P0300, P0301, P0302, P0303, or P0304) that no matter what gets replaced... the vehicle continues to misfire or run rough. This is were the engine compression test comes in to maybe save the day.
Here are the contents of this article at a quick glance:
- Symptoms of Low or No Engine Compression.
- The ‘Dry’ Engine Compression Test.
- Interpreting the Results of the Engine Compression Test.
- ‘Wet’ Engine Compression Test.
- Why an Engine Compression Test?
- Which Compression Tester Should I Buy?
- Related Test Articles.
You can find this tutorial in Spanish here: Cómo Verificar la Compresión del Motor (Honda 2.2L, 2.3L) (at: autotecnico-online.com).
Tools You'll Need:
- Compression Gauge Tester.
- A Helper
- Pen and Paper
Symptoms of Low or No Engine Compression
Two of the most common symptoms of low engine compression are:
- Misfire Condition (engine miss, rough idle condition).
- Usually caused by very low compression in one cylinder or...
- Uneven engine compression that varies more than 15% across all 4 cylinders.
- Cranks but Does Not Start Condition.
- 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 2.2L or 2.3L Honda 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:
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
If your Honda vehicle 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 2.2L, 2.3L).
When you have a situation where you have NO compression on ALL 4 cylinders, you'll see:
- The engine cranks very fast... and this fast cranking speed is very noticeable.
- The ignition system is Sparking all 4 spark plugs... so you know it's not an ignition system problem/issue.
- The fuel injectors spray fuel.
- You can confirm this with a Noid light test.
- Also, you can confirm this, although indirectly, by removing the spark plugs and checking to see if they are fuel soaked (fuel fouled).
- Fuel pump is working and providing pressure.
- The most common causes of this scenario, are:
- Blown head gasket.
- Broken timing belt.
- 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 2.2L, 2.3L Honda.
The ‘Dry’ Engine Compression Test
Let's jump right into the engine compression test.
Before you start, let me just say that you'll be working around a cranking engine, so you have to be careful and stay alert at all times.
This is a pretty easy test and at the end, I'll show you how to interpret your test results. Now, if it turns out that one or several cylinders, on your Honda, do have low or no compression... the next step would be to do a ‘Wet’ engine compression test (and I'll show how to do one too).
Alright, let's start:
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.
Now, if you're doing this test because your car doesn't start, then don't worry about the engine being warm.
Disconnect all of the four fuel injectors. This will prevent fuel from being injected into the cylinders as you crank the engine.
Disconnect the distributor electrical connectors. This will prevent the ignition coil from firing off spark to the spark plug wires.
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!
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.
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.
After testing all four cylinders and having written down all of your compression test readings, now you need to interpret the results, for this, turn to the next page...