[V8] 5spd throttle body questions

[dsaad at icehouse.net]

I think you are correct Steve about the emissions effect, but the dashpot
is (was?) also useful on carburetted motors to prevent stalling.  In
particular, I put one on my old Jeepster so I could make the shift from
2nd to 1st at max RPM in low range while on a stupid steep incline. 
There may be a similar use here to prevent flooding/stalling at high RPM
shifts - and this is why it is only found on the manual transmission
cars.

Dave


> AFAIK the dashpot is in effect
an emissions control device ... the MT cars
> have it because they
are often operated at high manifold vacuum (throttle
> lift during
shifts) which causes high NOx.  It gives the engine RPMs a
>
chance to drop before the throttle plates completely shut.
> 
> Since #2 has an engine intended for an AT car the TB has no
dashpot.  I
> have
> noticed no functional difference on
#2 as a result of having no dashpot.
> It's a good thing that
quattros don't get smogged on the dyno though ...
> the
>
lack of dashpot might cause high NOx at shifting.
> 
> My
tuppence on the high idle problem is not to worry about the dashpot or
> trying to adjust it ... I agree that the problem is likely to be
related
> to
> the vapor recovery system.  There's
supposed to be a solenoid which closes
> the path to the intake
from the carbon canister. ISTR reading that you
> were
>
able to draw air from the canister ... is perhaps the solenoid
remaining
> open and allowing air into the engine bypassing the
throttle body?  One of
> the output checks the ECU has opens and
closes the canister valve, you may
> want to run this to see if
you can hear the valve clicking open and shut
> ...
> 
> 
> Steve B
> San Jose, CA (USA)
> 
> -----Original Message-----
> 
> I had one of those
inuitive mornings where you fix things in your mind as
> you are
slowly waking to concsiousness.  I remembered that the 5spd cars
>
have the dashpot to aid in engine rpm control during shifts.
> 
> Is there any difference other difference between the 3.6 and 4.2
cars?
> Venturi diameter, etc?
> 
> Also, I seem
to recall that someone has used a non 5spd TB on a 5spd car
> and
reported no real difference or trouble shifting.  Was that you Steve
> Buchholz?
> 
> I've been paging through etka and
realizing/remember just how simple these
> are when compared to a
turbo 5.  There's like five vacuum lines and 3
> breather hoses. 
That's it.  Any other vacuum leak would have to come from
>
something more troublesome like a bad seal on one of the parts of the
> intake manifold or throttle body.
> 
> Still trying
to find some info about adjusting the dashpot.
> 
> Ed
> 
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