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Old 02-26-2020, 12:45 PM   #480 (permalink)
Ecky
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Join Date: Dec 2011
Location: New Zealand
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ND Miata - '15 Mazda MX-5 Special Package
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Quote:
Originally Posted by Piotrsko View Post
I make my reservoirs from schedule 80 plastic pipe with appropriate glue in fittings.

If the vacuum is leaking from your master cylinder, you may need a rebuilt/ new booster. I have had a couple go bad. You want to get two brake applications engine off.
So, I'm looking into this a bit more.

When the engine is off in a stock Insight, there's still vacuum to operate the brakes another 5+ times, and this vacuum can last quite a while so long as one doesn't press the brake pedal too many times.

It appears stock cars have two MAP sensors - one on the throttle body and one in-line with the vacuum hose going to the brake master. This second one is (presumably) to detect when to restart the engine if vacuum gets too low at the brake master while the engine is off.

So, to me, this suggests there IS a check valve somewhere. But where is it? Is it part of the intake manifold? I'll have to dig around under the hood of my 2nd Insight. I'm sure I can just add a valve and make it work, but I wonder how the OEM system did it.
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