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.
Contents of this tutorial:
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 four 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.
Which Compression Tester Should I Buy?
There are lot of engine compression testers to choose from and many places to buy them. I'm gonna' make two recommendations to you:
1) Which one to buy: The engine compression tester that I have always used is the Actron CP7827 Compression Tester Kit. My only complaint about this engine compression tester is that it does not come with a case to store it in.
Engine Compression Gauge Testers
2) Where to buy: You can buy an engine compression tester just about anywhere, but you'll end up paying more for it (especially at your local auto parts store). The above links will help you comparison shop. I think you'll agree it's the better way to save money on the compression tester!
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).
NOTE: 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, 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.
Alright, let's start:
Disconnect all four fuel injectors from their electrical connectors. This will prevent fuel from being injected into the cylinders as you crank the engine.
Disconnect the distributor from its electrical connectors. This will prevent the ignition coil from firing off spark to the spark plug wires.
Disconnect the spark plug wires from the spark plugs.
NOTE: Before you disconnect the spark plug wires, label them with the cylinder number they belong to.
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.
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 your helper 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.
Let's interpret your test results:
CASE 1: Low or no compression in two or ALL cylinders. This tells you you've got serious engine mechanical problems.
The most common issues would be:
- Blown head gasket.
- To further test this, I recommend the following tutorial: How To Test For A Blown Head Gasket (Honda 2.2L, 2.3L).
- Broken timing belt.
- To further test this, I recommend the following tutorial: How To Test For A Broken Timing Belt (Honda 2.2L, 2.3L).
- Engine thru' a rod.
CASE 2: One or two cylinders are producing a low compression value. Up to a certain point this could be normal, but if the value is too low you'll have a rough idle or misfire problem on your hands.
The next step is to do some math to find out if this low compression value is within a normal parameter or not. Go to: Interpreting Your Compression Test Results.