[T3] '72 FI won't idle down

[Jim Adney]

On 12 Jun 2026 at 21:13, Keith Park wrote:

> Well, if your at, say, 1/8 throttle accelerating, your going to run leaner
> with the idle air bypass than you are without it right?  Remember, this is
> a T4, may be a bit different...

That reasoning only works if the fresh air can slip in without the pressure 
sensor noticing. That would be the same as saying we should never press 
down on the throttle, because that will lean out the mixture.

No matter the route, any air getting into the IAD is the same as any other air, 
and the pressure sensor measures the total pressure, where the total 
pressure is the sum of all the partial pressures from each source. The 
pressure sensor can't tell and doesn't care where each molecule came from.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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