I just cleaned the throttle body in my '01 Mitsubishi and there sure was lots of crud in there. My question is, where does all this stuff come from? Is it from the EGR? The PCV? Vapor from the intake manifold? Just trying to figure out the underlying cause, thanks!
Throttle Body Sludge - Where does it come from?
- Thread starter Chuck1986
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oil vapour deposits, residual fuel vapours coming back from the intake side of the valve openings, etc.
With advancements in EFI technology and control, the latter part is pretty much a rarity (unless you have leaky fuel injectors). For the 1st part, watch out for high NOACK volatility oil and opt for one that doesn't vapourise easily.
Sometimes, a blocked/partially clogged PCV valve would contribute to this also.
As with some engines w/ notorious valve stem seal leaks, the deposits may also come from motor oil seeping past the valve guide seals.
Q.
With advancements in EFI technology and control, the latter part is pretty much a rarity (unless you have leaky fuel injectors). For the 1st part, watch out for high NOACK volatility oil and opt for one that doesn't vapourise easily.
Sometimes, a blocked/partially clogged PCV valve would contribute to this also.
As with some engines w/ notorious valve stem seal leaks, the deposits may also come from motor oil seeping past the valve guide seals.
Q.
The build-up wasn't too bad, considering the car has 60k miles on it. There was this rusty-looking oily crud on the back of the butterfly valve which really has made me realize I need to start doing the throttle body cleaning every 15k miles - dirt cheap and a small time investment.
During my first start-up my idle was up to nearly 1800 RPMs after the cleaning..that's very high considering how hot it was outside, is this cuz I cleaned so much off that the ECU needs to learn about the extra airflow I've caused?
Lower evaportation rate oil helped me.
I also installed a catch can....but in my case, very little ends up there (with Redline oil though) in warm weather......I get a good bit in winter.
When the oil vapors from the PCV system combine with the carbon, etc from the EGR system.....it can make a kind of tar buildup....maybe that is the "rusty-looking" that you see.
It is important for the PCV system to have the correct flow, so don't do something that would reduce that.
I also installed a catch can....but in my case, very little ends up there (with Redline oil though) in warm weather......I get a good bit in winter.
When the oil vapors from the PCV system combine with the carbon, etc from the EGR system.....it can make a kind of tar buildup....maybe that is the "rusty-looking" that you see.
It is important for the PCV system to have the correct flow, so don't do something that would reduce that.
All the stuff mentioned in the first post are the major culprits. I'll just add that some pollutants in the air can make it past the filter and collect in the intake. I recently had occasion to inspect the MAF screen on my dad's car. The screen is on the throttle body with nothing but a duct between it and the air filter. It was filthy dirty.
JTK
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You shouldn't be getting too much junk upstream of the throttle plate on a healthy engine with a fully functioning PCV system. Downstream of the throttle plate is a different issue. All your PCV vapors, oil and exhaust from EGR will build-up in the plenum without fuel to wash it away like it will on a TBI or carburetor equipped engine.
Joel
Joel
Quote:
During my first start-up my idle was up to nearly 1800 RPMs after the cleaning..that's very high considering how hot it was outside, is this cuz I cleaned so much off that the ECU needs to learn about the extra airflow I've caused?
No.
Crankcase ventilation systems, and whatever is vapor when he valves are open and the engine is off. With a common manifold, they will bleed/mix together.
This is why I use a catch can on my PCV system, and have no build up on my throttle plate/bore, and Idle Air Control motor. I used to get some.
This is why I use a catch can on my PCV system, and have no build up on my throttle plate/bore, and Idle Air Control motor. I used to get some.
I get this on my Expedition. When the throttle gets sticky, I clean a bunch of crud off my throttle body. I just assumed it was from my K&N filter!
T
T
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Inaudible backfires can do this. The top of my throttle body is spotless. The underside of the plate is black. My CCV metered orifice is plumbed to the far rear of the plenum for #6 cylinder. I somehow think that the pulsing in the intake isn't going to stratify the limited CCV flow upstream to the underside of the throttle plate all by itself.
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