Jim,
Just got done pondering this question myself.
Have concluded the "carbon"--which is downstream of the throttle plate--must
be coming from various vacuum inputs to the intake manifold, probably 90% or
more from the PCV valve (whose job it is to allow crankcase blowby to be sucked
into the intake manifold ... hence the carbon buildup).
bs
********************************************
Bob Spidell San Jose, CA bspidell@comcast.net
'67 Austin-Healey 3000 '56 Austin-Healey 100M
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Subject: Carbon Buildup, was Re: question on C (neither L nor B)
>
> Where does the intake side carbon build up come from? I recently addressed a
> carbon build up problem on our 1998 Dodge Neon R/T with the 2.0 DOHC engine.
> The throttle plate was sticking after being parked for a while. I cleaned a
>ton
> of black soot from the throttle body. And I have seen this build up on other
> cars as well, including the Ford 5.0L engine I'm working on. Where, exactly,
> does this stuff come from?
>
>
>> In addition to the things others have mentioned, Toyotas of this era
>> had some problems with intake system carbon buildup. It typically
>> caused problems with the engine hot -- the gunk expanded enough to
>> keep valves from sealing properly. I'd try some aggresive fuel system
>> cleaner.
>>
>> --
>> David Scheidt
>> dmscheidt@gmail.com
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