Testing the engine compression on the 1.6L DOHC engine in your Ford Fiesta is a breeze, since the spark plugs are very accessible.
In this tutorial, I'll explain how to perform the test in a step by step manner and I'll also tell you how to interpret your test results.
Whether a compression problem is causing a misfire or an engine no-start problem, I'll help you figure it out.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- 1.6L Ford Fiesta: 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018.
Symptoms Of Low Or No Engine Cylinder Compression
As mentioned at the beginning of this tutorial, engine compression problems usually cause one of two problems.
The engine compression problem will cause a misfire problem. This means that the engine will start and run but it's going to run with one or more dead cylinders.
In the worst-case scenario, an engine compression problem will keep the engine from starting. It'll crank but not start.
When an engine compression problem is allowing the engine to start, you're going to see one or more of the following symptoms:
- Bad gas mileage.
- Blue smoke coming out of the tailpipe.
- A heavier exhaust smell coming out of its tailpipe.
- Engine is not as peppy as it was once.
- Rough idle that goes away as soon as you accelerate the engine.
- The check engine light is illuminated on the instrument panel.
- Misfire trouble codes illuminating the check engine light. You many see one or more of the following:
- P0300: Random Cylinder Misfire.
- P0301: Cylinder #1 Misfire.
- P0302: Cylinder #2 Misfire.
- P0303: Cylinder #3 Misfire.
- P0304: Cylinder #4 Misfire.
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.
TEST 1: Finding The Dead Cylinders
I'm gonna recommend that you test the compression of all four cylinders. This way, we can get a complete picture of the engine's internal health.
Once you've got all four compression readings, I'll help you interpret them in the 'CASES' section below the test instructions.
If you don't have a compression tester, you can borrow one or buy one from your local auto part store. If you'd like to save a few bucks, check out my recommendations here: Which Compression Tester Should I Buy?
IMPORTANT: If the engine has been running for any length of time, let it cool down completely before removing the spark plugs.
OK, these are the test steps:
- 1
Disable the ignition system by disconnecting the ignition coil pack from its electrical connector.
This will prevent the ignition coil from sparking during the test. - 2
Remove the spark plugs. Remember, the engine can not be hot!
When removing the spark plugs, be careful not to drop any on the floor, or you run the risk of having the spark plug's porcelain insulator crack and then you'll have a misfire on your hands. - 3
Thread the engine compression gauge into the spark plug hole for the number 1 engine cylinder.
NOTE: Hand tighten the compression gauge only! Do not use any type of tool to get it tight. - 4
Have your helper crank the engine till the needle on the compression gauge stops climbing.
- 5
Record the value at which the needle stopped and the number of the engine cylinder on a piece of paper.
- 6
Release the pressure on the gauge and repeat step 4 and 5 one more time.
- 7
Repeat test steps 3 - 5 on the remaining cylinders.
Let's examine your test results:
CASE 1: One or more cylinders had a much lower compression value than the others. Up to a certain range, this could be normal.
To further interpret these test results go to: Interpreting The Compression Test Results.
CASE 2: All four cylinders had almost no compression or 0 PSI compression. This low or zero compression on all cylinders will cause the engine to not start.
Having a compression value close to 0 PSI or 0 PSI is usually due one of the following problems:
- A busted timing belt.
- Blown head gasket.
- The engine threw a rod.
CASE 3: The compression value of all four cylinders was similar and above 120 PSI. This test result lets you know that an engine compression problem is not behind the misfire condition and/or engine no-start problem you're troubleshooting.
