2004 mazda 6 3.0 misfire

One of our neighbors came to us and mentioned that she had a service engine light come on in her car. She wanted to know if I could look at it and put my scanner on it to see what was wrong. My scanner showed that there was a misfire in the number 2 cylinder. I mentioned to her what the possibilities could be and my suggestions about what we could do.

Whoops! it’s missing a nut. Or a stud?

So we started out getting STP Fuel Injector Cleaner and I suggested changing the spark plugs. We went with NGK spark plugs which were recommended for this car. I tore into this little car starting with disconnecting the negative cable on the battery.  Next, I start with the studs holding the plastic cover that is covering the intake manifold. Then I start disconnecting everything connected to the air filter box.

Starting with the mass air flow sensor, then I finish with the clips to the top of the filter box. Then the tubing going to the throttle box on the intake manifold. Now, remember don’t just start yanking things quickly, remember where everything goes, because everything has a place and if you don’t rehook it up right you will not have a well-running car.

Now you have a few squeeze clamps on some hoses here, so I grab my channel locks to pull these off. I just pinch them and push them up on the hose, it always works best for me to leave them on the hoses so you can’t lose them.

Be careful disconnecting some of these plugs, because some clips may be brittle from being in the engine bay, be patient and work with them and this is coming from the voice of experience. Some of these bolts pictured here around the intake manifold are 10mm and some are 8 mm and they are in tight places and be patient when working here.

There was an EGR valve, you will see in the pictures that it made it much easier to do it this way, much less of a headache also a time saver!

FINALLY. I get to the SPARK PLUGS! Now the fun begins. I can replace the plugs. These spark plugs are under each one of these coils they are powered individually. So it makes it much easier so you don’t screw up a tune up!

EGR Valve.

I will be showing an “Old School” trick I taught this to myself when working on the Oldsmobile Quad-4 engines from late 80’s to the early ’90s. While working with a friend, he had this engine and my spark plug socket didn’t have the little rubber grommet to grab the porcelain top of the spark plug. So I quickly remembered that I had a piece of rubber fuel line in my toolbox.

So I fed it down the tube to the top off the spark plug and it pulled it right out!   To this day I still use this trick and this is car number 9 it’s been used on. I finally found the reason for the misfire. The computer got it wrong and right. It’s not cylinder 2, it is also the cylinder next to it. The two plugs are actually being soaked with motor oil because the seals that go around the tubes that the spark plugs are seated in are worn out and need to be replaced.

Putting everything back together now that the plugs are all finished. Remembering where everything goes as for hoses and electrical connections. Now, when I reinstall hoses with clamps, either squeeze clamps or screw type clamps, I like to have them up and easy to get to so if I ever have to go back in and work on it again in the near future. It just makes the job easier. She is all buttoned up for now and now we have ordered the seals for it and the throttle sensor.

Lucky for us it is not anything major like a head gasket or having to have the heads machined. So this is going to be a cheap and easy repair and save this owner time and money and definitely labor! That’s the one thing I enjoy doing the most is helping people save money.

 

What causes a Mazda 6 to misfire?

Common reasons for this to happen: Faulty spark plugs or wires. Faulty ignition coil. Broken piston rings. Burnt or bent valves.

What are the most common problems with the Mazda 6?

A: Some of the most common Mazda6 issues include transmission failure, stalling engines, spiders in fuel hoses, and dangerous airbag inflators.

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