Engine dying with brakes issue

[KyleSeal]

I have a K30 with a big cammed 454, 4 speed, with hydroboost brakes. Lately Ive been having some issues. When I give partial brake, like coming up to a stop light while in neutral, the whole truck will shake some and then the idle will drop to about 1500 and virtually drop all the way down to 200 rpm like its going to die. I am still able to keep it going by giving some gas but this has become an issue because it makes the truck impossible in traffic.

All fluids are topped off, could there be air in the system? I heard theres a diaphragm in the hydroboost system that tends to stick, causing something like this.

Does anyone have any pictures of the hydroboost system showing where such diaphragm is?

Another part to this issue is that the motor will try and die when turning the wheel while sitting still. Like it kills it. I know it puts some strain on the system but I dont feel that much strain is coming from a single turn of the wheel.


454, 4 speed, 6 inch lift with 35s.

[homemade87]

From the sounds of it especially when sitting still and turning the wheel and it drags it down , my guess you need some more tuning on the engine . With that big cam the vacuum is low along with timing and air fuel ratio . Just idling on its own with no drag it may be fine . The hydo system puts a load on it .

Same thing happens to automatics when you drop it into a gear . The rpm will drop to much when the tune is off .

Take a look at your timing and carb setting . The engine is more sensitive at idle ( low rpm ) . Once your tune is closer you problem will be helped alot . Also the big cam may require more rpm at idle as well .

[wilkin250r]

I can't fix your problem, but I may be able to help identify it. Let's look at this logically.

I don't have a hydroboost, but from what I understand, they're powered by pressure from the power steering pump rather than engine vacuum. When you're brakes are applied, your engine almost dies.

Also, the engine starts to die when you turn the wheel standing still.

BOTH of those issues involve the power steering pump, yes?

It's starting to sound like you either have a general engine problem (vacuum leak, carb settings, ect ect) OR your problem is somehow centered around the power steering pump.

[KyleSeal]

I dont believe I have a vacuum leak because I covered the carb with my hands and the engine died instead of revving back up. I suppose next I will move onto getting it better tuned and timed.

[Super_Dave]

Same thing happened to me. My new Summit HEI Dist went south. Bought another one from another supplier and problem went away.