decel valve same as bypass valve?

auditude at auditude at
Wed Mar 12 19:44:53 EST 2003

Hi Brett,

Right.  I do understand the different functions, I was wondering if they were the same part tho'.  An Audiworld poster and I were discussing this a bit, and he basically said they were the same part.  Initially I disagreed, but looking at the diagram on the SJM site, I think it might be possible.

One is called the deceleration cutoff valve, or something like that, and the other is call the throttle overrun valve, or something like that.

Neither TPC or the Worldpac sites seem to carry either, otherwise I would have compared part numbers.  I don't have access to a family album lately.

Btw, the AW poster is proposing a group buy of European single-pass 10v IC setups, if anyone is interested.



P.S. I sure would like to find out what your tranny whine is!

Brett Dikeman <brett at> wrote:
> At 12:45 PM -0500 3/12/03, <auditude at> wrote:
> >Is the MC airbox deceleration valve the same part as is used for a
> >bypass valve in the turbo applications?
> Decel valve on CIS cars is for shutting off the fuel when you're
> decelerating; the bypass valve is for helping keep the turbo spin by
> opening a path for air any time manifold vacuum is dramatically less
> than pressure at the turbo.
> Far as I know, they are completely different.

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