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- Mazda CX 5 Touring
I'm curious to know if there are any high mileage cars that have never had there valves cleaned of carbon and have never had a problem in that realm. Please let me know thank you !
Valve Clean High Mileage
- Thread starter shooter357
- Start date
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- 2020 CX-5 GT AWD
2020 Mazda CX-5 here with 166.700 miles and some change as of today. Never cleaned anything inside the engine. After an oil change at 146.429 miles, code P0421 popped so I eventually had to replace the exhaust valve with the integrated catalytic converter. At 164.745 miles I replaced the belts and the belt tensioner. Other than that, knock on wood, no major issues. Replacing air filters, spark plugs, does not count as major problems in my book.
2016.5 GT, nearing 130K miles
Although I wouldn't call that really high mileage, yet, so far there have been no issues with the valves and no codes from the system.
Changed plugs at 84K miles (a bit late, but I'd acquired the car pre-owned). Still on the spark coils, the original O2 sensors, MAF sensor, temp sensors. Still haven't opened the valve cover to deal with anything (seals, gaskets, leaking, or the intake valve deposits themselves). Regularly change oil and engine air filter, though don't consistently use top-tier gasoline.
This spring when the weather warms, I'm planning to clean the throttle body (w/ new gasket), clean the MAF sensor, and to do a couple of bottles of the STP Pro-Series Intake Valve Cleaner treatment. At ~130K miles, perhaps it'll help delay the need to do much further under the valve cover. Time will tell.
Although I wouldn't call that really high mileage, yet, so far there have been no issues with the valves and no codes from the system.
Changed plugs at 84K miles (a bit late, but I'd acquired the car pre-owned). Still on the spark coils, the original O2 sensors, MAF sensor, temp sensors. Still haven't opened the valve cover to deal with anything (seals, gaskets, leaking, or the intake valve deposits themselves). Regularly change oil and engine air filter, though don't consistently use top-tier gasoline.
This spring when the weather warms, I'm planning to clean the throttle body (w/ new gasket), clean the MAF sensor, and to do a couple of bottles of the STP Pro-Series Intake Valve Cleaner treatment. At ~130K miles, perhaps it'll help delay the need to do much further under the valve cover. Time will tell.
Unless the valve cover gasket is leaking or oil control valve needs replacing, why bother disturbing it unless there is some other issue. This past summer I replaced the valve cover gasket because of some oil (minor) leakage around #1 spark plug prior to changing plugs. It's a tight squeeze manipulating the cover back on because of clearance between a tight wire loom and the cam sprockets. Possibility of dislodging new gasket. I applied Mazda sealant at the specified locations on the head and still had a leak. Not wanting to remove again I just "slathered" sealant externally liberally around the leak area which did the trick.
I cleaned the throttle body a few years ago. Bought the gasket for a few dollars online. It was a Beck-Arnley that was identical (and made in Japan) to the Mazda gasket selling for~$20 from Mazda dealers online. The old gasket had enough resilience to be reused but got changed out since already acquired.
The OCV has a little leak, though not severe. And there's a little bit of oil off the typical spot at the left/rear of the valve cover.
You're correct in that it's not really worth it until problematic or something else is going on. Which is why I haven't done anything with it yet.
2016.5 CX-5 GT AWD @ 125K miles.
Throttle body cleaning and new gasket -- Took awhile. The carbon gunk was baked-on, in there. Took about an hour of soaking, brushing, soaking, brushing, again and again.
Intake valve cleaning -- Using the STP Pro-Series Intake Valve Cleaner, this fed the fluid (mist?) through a thin hose into the air intake hose immediately ahead of the throttle body. Ten minutes of revving at 3K rpms, 20 mins of highway driving, 5mins at 5K rpms, then another 10 minutes of driving to cool it down. Have a second can of the stuff, for when I get motivated to do a second treatment.
Results -- Already, I notice the throttle response is quicker. Uncertain if it accelerates a bit more briskly. The car's been having a lag and sluggish gear change, when pushing the throttle down a good bit. This time, even a moderate change in throttle angle resulted in a quick drop of a gear and solid acceleration. Felt more responsive. I'll monitor the next couple of tanks of gas, to see how the fuel efficiency is, though I'm sure there will be at least some instances of differences in routes and speeds. I will try to duplicate what I've done this past tank of gas, more or less, same essential routes, same style of driving, roughly similar percentage city vs highway.
Throttle body cleaning and new gasket -- Took awhile. The carbon gunk was baked-on, in there. Took about an hour of soaking, brushing, soaking, brushing, again and again.
Intake valve cleaning -- Using the STP Pro-Series Intake Valve Cleaner, this fed the fluid (mist?) through a thin hose into the air intake hose immediately ahead of the throttle body. Ten minutes of revving at 3K rpms, 20 mins of highway driving, 5mins at 5K rpms, then another 10 minutes of driving to cool it down. Have a second can of the stuff, for when I get motivated to do a second treatment.
Results -- Already, I notice the throttle response is quicker. Uncertain if it accelerates a bit more briskly. The car's been having a lag and sluggish gear change, when pushing the throttle down a good bit. This time, even a moderate change in throttle angle resulted in a quick drop of a gear and solid acceleration. Felt more responsive. I'll monitor the next couple of tanks of gas, to see how the fuel efficiency is, though I'm sure there will be at least some instances of differences in routes and speeds. I will try to duplicate what I've done this past tank of gas, more or less, same essential routes, same style of driving, roughly similar percentage city vs highway.
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Yes, it comes through the airflow system. The nasty gunk that has been accumulating inside intake manifolds for years since fuel injection, is formed from oil vapors/combustion gas blow-by introduced by way of the PCV (Positive Crankcase Ventilation) valve directly into the intake manifold to burn them in the combustion chamber. This allows fresh air into the crankcase and prevents pressure buildup that could cause oil leaks among other problems.
This gunk is also formed by exhaust gases tapped from the exhaust manifold and routed through the computer controlled EGR (Exhaust Gas Recirculation) valve into the intake manifold. The inert exhaust gas displaces some of the air in the combustion chamber and lowers the combustion chamber temperature to below that of which nitrous oxides are formed.
So in a nutshell, oily vapors and exhaust gas is fed into the intake manifold. Nice, huh? This is done downstream after fresh air comes into the throttle body past the butterfly.
N7turbo
2023 CX-5 2.5T ... 2024 MX-5 RF GT
Haha, yes. I remember almost posting "nitrous" and then thought ,no, that's not right, it's "nitric". And then wrote nitrous anyway.I think that's what you meant
Good post.
"Baked" was probably an over-the-top description. But the carbon (?) gunk that gets embedded onto the surface of the butterfly and walls of the throttle body was really on there, hard to get off. I termed it "baked", though it is upstream from the engine. I've no idea how high the temps get on the TB. Can't be too high, given it's got a rubber (?) hose attached between the TB and airbox.
