Engine miss when using power brake
Every morning at start up, the engine evacuates the entire booster, both sides of the diaphragm. As long as the control valve is closed, and the check valve is working,the engine cannot suck air thru the unit.
When you step on the pedal, immediately the control valve separates the forward chamber from the rearward chamber. Then it lets atmospheric pressure into the rear chamber in proportion to how far you are depressing the pedal. The vacuum side of the chamber is supposed to remain sealed. So stepping on the brakes and getting a rough-idling engine points to a failure of the vacuum chamber, in that somehow air is getting from the power-side of the booster to the vacuum side.
It may be a perforated diaphragm, or it may be a leaky control valve. In either case a replacement booster should fix it.
Now; as the power piston moves, a small and brief hick-up in engine rpm or quality can be expected as the vacuum side adjusts; but as soon as your foot becomes stationary, you can expect the engine to recover.
But yes re-plumbing the charge hose to the plenum will at least put #6 back on line; but now all cylinders will share the leak. At least maybe you can compensate by mixture screws..... until the leak in the booster gets really bad,lol.
Every morning at start up, the engine evacuates the entire booster, both sides of the diaphragm. As long as the control valve is closed, and the check valve is working,the engine cannot suck air thru the unit.
When you step on the pedal, immediately the control valve separates the forward chamber from the rearward chamber. Then it lets atmospheric pressure into the rear chamber in proportion to how far you are depressing the pedal. The vacuum side of the chamber is supposed to remain sealed. So stepping on the brakes and getting a rough-idling engine points to a failure of the vacuum chamber, in that somehow air is getting from the power-side of the booster to the vacuum side.
It may be a perforated diaphragm, or it may be a leaky control valve. In either case a replacement booster should fix it.
Now; as the power piston moves, a small and brief hick-up in engine rpm or quality can be expected as the vacuum side adjusts; but as soon as your foot becomes stationary, you can expect the engine to recover.
But yes re-plumbing the charge hose to the plenum will at least put #6 back on line; but now all cylinders will share the leak. At least maybe you can compensate by mixture screws..... until the leak in the booster gets really bad,lol.
