Brake booster almost stalls '86 1.8 dual carb... Normal???

I have an '86 Prelude with a 1.8 liter dual carb engine. When I press the
brake pedal hard the engine RPM drops a bit then stabalizes. When releasing
the brake pedal after pressing it hard/far the RPM drops to about 100-200
and the engine almost stalls. Is this normal? I know the engine is tiny, but
I would thnk Honda wouldn't make a brake booster so big that when vacuum is
applied it leans out the mixture to the point that the engine almsot stalls.
Perhaps there is a vacuum leak somewhere in the booster or lines connecting
to it? Any thoughts/ideas? Thanks.

Cory

 

You probably have a leak which is most likely in the booster.

JT

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Try this test for the brake booster, it may help you.
Start engine with the brake pedal depressed. If the pedal sinks
slighty, the booster is working. If pedal height does not change,
booster or check valve is faulty.
Or, Depress the brake pedal w/ engine running, then stop the engine.
Hold pedal down for 30 seconds. If pedal height does not change, the
booster is OK. If the pedal rises, booster is faulty.
Or, With engine off, depress the brake pedal several times. As you push
the pedal the height of the pedal should rise. If it doesn't, the
check valve may be faulty.
Check valve test: Disconnect the vacume hose that runs from engine to
the booster where it connects to booster. Start the engine. If you do
not feel any vacuum, check valve is faulty. The valve is located in
the vacuume hose you disconneted.
I hope this helps. Unfortunatly, I do not know if you have a bad
booster, that it will cause the problems you are having. Good Luck.