Re: [DML] Re: New here (Choke Plates)

[Greg Zapf <x86Daddy@xxxxxxxxx>]

Yes, the "choke" function introduced by the PO was a mis-use of the
cold start valve because they didn't know the CPR was responsible for
this functionality and was clogged up.  They basically replaced the
normal electrical connection to the cold start valve with a new one
wired to a momentary push button, which needed to be held and then
pulsed and finally released after 10 seconds or so to accomplish a
cold start...  After unclogging the CPR, I restored the normal
electrical connection (and purpose) of the Cold Start Valve.  As far
as previous owner hacks go though, this was relatively nice: they got
it running without cannibalizing or destroying anything else (the
original cold start electrical connection was in place).  It just took
me a lot of reading and learning to get to the point where I could
repair it properly.

--Greg
#2894

On 5/20/05, content22207 <brobertson@xxxxxxxxxxxx> wrote:
> Actually, a choke is a restrictive plate that physically prevents air
> from entering the engine (kind of like a throttle plate). You find
> them on carburetors, not fuel injection, because of the way
> carburetors work. Their purpose is to keep manifold pressure higher
> than normal even as the throttle plates open so that more fuel than
> normal is pulled into the engine. Fuel injection accomplishes the same
> thing by spraying more fuel than normal through the injectors.
> 
> On K Jetronic, this is done via the CPR (Warm Up Regulator). Cold,
> throttle plate movement, which correspondingly lowers the air sensor
> plate/raises the metering piston, results in richer than normal fuel
> metering through reduced counter pressure. As the engine warms up, the
> CPR increases counter pressure, bringing fuel metering closer to normal.
> 
> The only purpose of the cold start injector is to provide a momentary
> shot of extra fuel during the cranking process. Once started, it has
> absolutely no effect on the engine (is no longer spraying). It's
> function is actually equivalent to pumping an accelerator pedal
> attached to a carburetor (squirting fuel from the accelerator pump),
> not a choke plate.
> 
> Bill Robertson
> #5939




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