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Discussion Starter #1
So as some of you may know, I recently purchased a 2004 Mazda 6 2.3 5-speed with 350k km (217k miles). What are some tune-up items I should look at to get better mileage and durability out of my car?

I was considering the following:
Fuel Filter - is this a regular change item?
Throttle Body clean - suggested?
Sea Foam - should I worry about killing o2 sensors, etc at this mileage?
Oil Change
Spark Plug Change
Transmission Fluid Change
Air Filter - this was recently changed by previous owner
PCV - suggested?

Any other items?

Thanks!!
 

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Having a clean throttle body is always a good thing and its super easy along with the plugs.

Fuel filter is in the gas tank so i would probably leave that alone, i would recommend you do a air/fuel induction clean and oil changes are always good (probably want to run some thinker oil for the mileage, tranny fluid is also a good one. You should be fine with the air filter if it was just changed. You can feel the hoses and if they are soft then i would probably change those. Might as well check your cabin air filter while you at it.
 

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Discussion Starter #3

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It throughly cleans throttle bodies fuel injection nozzles intake manifolds, valves and most importantly combustion chambers. This kit costs anywhere from 10-30$ and if taken to a dealer its 150$+ so definitely do it yourself.

I did the fuel/air service at 110k and holy crap i had alot of junk blow out the exhaust, its fun to watch all the shit come out (so you know it actually did something)
 

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ya haha, sorry i had never heard of seafoam. You are able to buy the fual/air kit from any dealership as well. I believe it comes with throttle plate cleaner as well but i found most of my build-up on the back side of the valve so that requires you to detach the tb from it engine.
 

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good start to your list.
plug wires
brakes
clutch/brake fluid (same reservoir)
tires?
PCV is a pain in the tuchus. You have been warned.
Wiper blades
what's the condition of the driver's seat right side bolster? (lots of breaks reported here.)
light bulbs?
spray cleaner the MAF/temp sensor.
coolant
alignment/balance
sway bar links/mounts
shocks/springs

basically, assume any consumable will need service at some point and soon.
 

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Change your plugs, I can't emphasize that enough. :)

Also, walk around the vehicle and ensure that all your lights are functioning properly.

How are your breaks? Do the rotors feel warped? Does the car pull a certain direction when stopping?

I would definitely visually inspect all break components to make sure everything is within spec.

If not go ahead and change your pads and rotors. :)
 

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Discussion Starter #9
Thanks for all the tips so far guys.
The rear rotors/pads and right rear caliper were shot, which caused a heavy pulsing in the brakes - I replaced them and the brakes feel solid. The car doesn't pull when trying to stop, the rotors feel good now, but there is heavy noise from the tires because they are worn out and I believed cupped causing a bit of a vibration.

I inspected front CV joints, ball joints, exhaust system, brake lines, and a few other items and they all looked good.
 

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Discussion Starter #11
I did the plugs today and cleaned up the engine bay. The problem is now the idle is more rough and it keeps jumping up and down (not sure if the ECU is trying to "learn" the new plugs?).

I suspect I may have damaged one of my plugs, because when I tried to open the gap (after the gap was closed too much), I pressed onto the electrode by accident and somewhat bent it - I tried to bend it back, but I am sure its not perfect. I am thinking I should replace this plug? I used NGK TR55IX with a 0.050" gap.
 

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Discussion Starter #12
Also which sparkplug wires should I buy to replace the current wires?

Car is now throwing P0138 code as well (it actually says both P0138 and P0138 P). Not sure what "P" is for? This is the heated rear o2 sensor I believe and might have been killed when I seafoamed the engine.
 

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The P is just a letter appended to the front of CEL faults. I don't even know what it means, to be honest.

Anyway, it is likely that the seafoam killed the o2 sensor. I don't think they are tremendously expensive or difficult to change yourself.

As for the plugs, I used the exact same plugs, but mine came in the box gapped to .054, I just left them that way and the car has been running fine ever since.

Also, the rough idle could be a symptom of the bad o2 sensor. I would smell the exhaust. It could be running really rich because of the bad sensor. A replacement would likely get rid of all of your symptoms.

As for spark plug wires, I just used a set of Duralast ones. I can't complain, they get the job done and weren't very expensive.
 

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Discussion Starter #14
The P is just a letter appended to the front of CEL faults. I don't even know what it means, to be honest.

Anyway, it is likely that the seafoam killed the o2 sensor. I don't think they are tremendously expensive or difficult to change yourself.

As for the plugs, I used the exact same plugs, but mine came in the box gapped to .054, I just left them that way and the car has been running fine ever since.

Also, the rough idle could be a symptom of the bad o2 sensor. I would smell the exhaust. It could be running really rich because of the bad sensor. A replacement would likely get rid of all of your symptoms.

As for spark plug wires, I just used a set of Duralast ones. I can't complain, they get the job done and weren't very expensive.
The rough idle only started after I swapped the plugs for the new ones. I am thinking I may have damaged one of the plugs, apparently the internals on these plugs are very delicate?

Do you know where the rear heated o2 sensor is actually located?
 

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The rough idle only started after I swapped the plugs for the new ones. I am thinking I may have damaged one of the plugs, apparently the internals on these plugs are very delicate?

Do you know where the rear heated o2 sensor is actually located?
I would drive the car for a little while longer and see if the idle doesn't smooth out a bit. Generally when the ECU is reset my car will run like shit for around 100 miles. If it lingers on past this period, than you probably did mess up one of your plugs. I hope you can remember which one it was. :)

I think the 2004's only have two sensors. One in the cat and one of the manifold. So, it's likely the one in the cat. This one doesn't control fuel trims. I think it is there solely to make sure you have a cat on the car. If you don't mind the CEL, you can get by without replacing it. :)
 

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^+1 if your upstream O2 goes out it will run very rough. You can test if that's what is causing the bad idle by unplugging them one then the other. I had an upstream go out and it did not throw a code. Huge PITA to diagnose. You can find the connectors under the driverside near the exhaust.
 

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i need some help, i have a 06 mazda 6 3.0 v6 and its got a bad misfire and i checked the fuel pressure and it was in the normal range. seems like its starving for fuel and when i take the scanner to it all it says is ''multiple cylinder misfire'' havent messed with coils or plugs yet, im thinking possibly a clogged fuel filter?
 
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