LLLosingit

iTrader: (4)

My thought is that manifold vacuum is strong enough to pull the injector down tight to the manifold. Happens with pressure so I don't see why it wouldn't work with a vacuum.

RockinWs6

Actually vacuum doesn't pull the manifold down, Engine displacement creates a low pressure area in the manifold and atmospheric pressure pushes on the area. Same reason why air enters the intake manifold, Atmospheric pressure enter the low pressure area in the manifold created by displacement in the piston areas.

Cold the intake is smaller and doesn't seal as well, hot the intake is larger and more flexible and seals much better. That's why on these cars you will experience a rough cold idle that disappears as soon as it gets into closed loop. If you watch the fuel trims close you can watch the manifold sealing up as it gets hot.

If you want to see real nasty reality, use a smoke machine on a cold LS1 manifold. You will be surprised how poorly it seals cold.

SlasherVRGR

iTrader: (1)

I do in my truck, throws lean codes when it's really cold out and you can hear the intake gaskets leaking. Once it warms up it goes away.

LLLosingit

iTrader: (4)

Isn't that the definition of creating a vacuum?

john stewart

happened to me going thru a car wash car started to stumble since then i check the intake and header bolts every time i check my oil only takes a minute

gagliano7

I am suprised you never heard this. There has been many threads on this problem. Must be a horrible feeling when it happens.