How To Fix Code P0300 (Random or Multiple Cylinder Misfire) on the Seventh Generation Toyota Celica GTS, in Five Easy Steps!

Does your check engine light come on without any apparent symptoms? Does it sometimes stay there for a week or two, then disappear? Do the symbols “P0300” keep re-occurring in your nightmares? Are you beginning to question your own sanity?

This is common for most Celica owners. You’ve come to the right place. Your car might be suffering from the elusive “phantom misfire.” But before you call up your neighborhood exorcist, first see if these five easy steps don’t resolve your P0300 problem.

Step 1:

A compression test is a great way to gauge the overall health of your internal engine components, and will help narrow down the cause of your P0300 code. Find a compression gauge, pull out your coils and spark plugs, and unplug the injectors. During this time, you may be tempted to ask the internet questions like:

• Should there be oil on my ignition coils?
• Is it ok if my valve cover is on crooked?
• Should my spark plugs be covered in black stuff?
• Are my engine mounts supposed to be leaking brown goo?

Look, if you want to be so pedantic about everything, then fine, the answer to these questions, technically, is ‘no, no, no, and no,’ respectively. But why bother with all that negativity? Consider the bright side. Today, you learned that engine mounts are filled with some kind of fluid. Who knew? The world is full of wonders.

Step 2:

Use the compression gauge to test each cylinder. Write down the results.

For the Celica GTS’ engine – the high-revving, high-compression Toyota/Yamaha 2ZZ-GE – the compression specifications are:

• Compression pressure: 203 psi or more
• Minimum pressure: 145 psi
• Difference between each cylinder: 16 psi or less

Now, take a look back at your results. If your numbers look something like this:

• Cylinder 4: 184 psi
• Cylinder 3: 131 psi
• Cylinder 2: 119 psi
• Cylinder 1: 92 psi…

Then just act normal, and calmly proceed to reinstall your plugs and coils, reconnect the injectors, and shut the hood. Remember those results you wrote down? Go ahead and toss those in the nearest garbage can, then drive away.

As you drive, you’ll notice that the engine seems to be pulling just fine, all the way up to redline. You may even notice that your check engine light has disappeared without explanation. Don’t worry, this is just God’s sense of humor.

You did well today. Go home and treat yourself to a beer or seventeen.

Step 3:

It’s about a week later. You’ve mustered up the courage for another compression test. This time, make sure to follow the procedure carefully. Warm up your engine first. Tighten the hose adaptor to the socket torque spec. Keep the throttle wide open while cranking.

Test each cylinder, and write down the compression readings.

This is when you notice that the results are pretty much the same as last time.

Step 4:

Dismantle the front of your motorcycle. You’ve been wanting to swap out those sideways-donkey-ear blinkers for a while now, and now’s as good a time as any.

As you proceed with the installation you’ll realize the job is not as simple as you thought. You’ll get one headlight to work and sort of be in the right spot. But now the whole front is uncomfortably asymmetric, there are loose wires clearly sticking out, and it looks like everything could short circuit at any moment.

You’ll accept this job as completed for now, because you feel that it is an apt representation of your current state of mind.

Step 5:

Drive your car. Yes, it seems to be running just fine. The numbers indicate that three-quarters of your engine is below minimum compression. And yet, here you are, cruising along at 90 mph, smoother than a warm stick of butter.

At this point you will start to have philosophical thoughts. This is normal.

Everyone knows at least one person with that same old story – the doctors told them that they only had so little time to live, and then they ended up living so much more time than that. Maybe your car is like one of those people.

Or maybe it’ll explode in thirty seconds. Life is such a fragile and precious thing.

You consider the financial ramifications of doing some deep-engine repairs and repress those thoughts almost immediately on account of your unfortunate predicament of monetary illiquidity. You move on to the next best affordable solution – spiritual guidance. You’ve never been a religious person, but the fact that you seem to be driving a four-wheeled miracle is somewhat changing your mind about the idea.

With so many religions to choose from, it’s simplest to go with the most effective one we have so far – Alcoholics Anonymous. With AA, you get a simple, achievable metric that defines success versus failure. You don’t have to worry about getting wrapped up in any political maneuverings, assassinations, executions, torture, pillaging, crusades, jihads, dress codes, etc. And, unlike the rest, the instructions are pretty clear.

Now, you aren’t really an alcoholic, at least not full-time, but you figure you can adopt the AA framework to suit your own situation.

Step 1:

“We admitted we were powerless over alcohol —” Except here you just cross out alcohol, like that, and instead put P0300 – Random or Multiple Cylinder Misfire.

Problem solved! Happy driving!