My grandfather has a 2007 Buick Rendezvous and it stalls when warm and when coming to a stop. It restarts right after stalling. Two mechanics so far gave up on figuring it out.
100k miles, automatic
no codes
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thanks next week my grandpa is going to have the booster tested
Well, not much of a mechanic, were they?
Stalling during braking is often caused by a leaky brake booster. Brake boosters use vacuum from the engine intake manifold, and when it leaks, too much air gets into the engine. The vacuum hoses, connectors, valves or the booster itself just get brittle from time and heat and fall apart. The leaks can sometimes be almost invisible (hairline cracks.) It can also be hard to find because it only leaks during hard braking.
You might be able to find the leaks by hitting the brakes and listening for the hiss under the hood. You could also try holding some propane up to the parts with a small unlit torch (engine will get louder and faster). But probably the most surefire way is to use a smoke machine. Search Scotty's youtube channel for his videos about it.
Two mechanics so far gave up on figuring it out.
Well, Scotty's not
https://youtu.be/2Mow8mSLsXA?t=260
