OK so I am seafoaming my motor today. I start the car and let it warm up. When warm i pulled off the brake booster line, BUT instead of idling up it about died. It idled up when the seafaom was added but when I would stop it would drop again. I got the seafaom in and reinstalled the hose and it went back to normal idle.

Why does mine not idle up like its suppose to?? I have a cam if that makes any diff.

 

if you disconnect your brake booster hose, you're essentially creating a huge vaccum leak...

Your motor should stall or at least act like it's going to stall...

 

yeah and the car SHOULD idle high when this is created.

 

If the idle does not rise with the brake booster hose disconnected it means you most likely have a huge vacuum leak elsewhere.

What does your car idle at in park, and what are the IAC counts?

 

in park it idles at about 7-750 it has a 503 cam with stock tune though also. Think maybe my IAC is going bad?

 

Don't worry about it. The line is too big of a leak for the engine to run. There is nothing left to pull in the gas when ya disconnect that big of a line.

 

With speed density, yeah i'd expect the idle to go up, with MAF no your idle should go down as you are almost entirely bypassing the MAF sensor, the majority of your air is not being seen by the engine and as such the engine is not injecting enough fuel.

 

Not if the vacuum leak is significant (like that big hose). You are worrying about nothing.

 

A carb will die too. So will speed density. It has nothing to do with computer's but the internal workings of an engine.


Bottom line ya are pulling air in from the wrong place.

 

Speed density looks at manifold vacuum and a VE table so when the Manifold vacuum goes down it compensates automatically, MAF and Carb function much different from speed density, it definately has to do with the computer and not the engine.

 

If a big enough vacuum leak is created, it's not going to make any difference what type of engine management there is. No amount of compensation is going to make it run.

 

OK then tell me why a 1952 Chevy will do the same thing with NO computer

 

Because...umm...well...oh, sorry, it was a rhetorical question.

 

 

Oops, I was automatically thinking of my MAFless speed density LT1. My idle jumps up quite a bit with the booster hose disconnected