I keep reading that one should check for vacuum leaks when having rough idling problems, etcetera. However, just how does one go about checking for a leak when there are so darned many different vacuum hoses running all over herk and deck under the hood. This is a California car so there are all kinds of emissions controls scattered all over under there.

The manuals say to spray water on things to see if it seals a leak and raises RPMs temporarily.

I saw one tip on YouTube where a guy sprayed "starter fluid" all over things listening for the RPMs to go up. The theory is that if any starter fluid gets sucked in where there is a leak, then it will A) temporarily seal the leak and B) run some starter fluid through the engine, both of which tend to increase RPMs.

I tried that and got no results. However, there are plenty of places where vacuum hoses run that I could not get to with the spray, such as through the firewall or farther down under other stuff.

So, I was wondering: Is there some trick that one can do to tell, for sure, whether there is a leak or not so one is not running around chasing gremlins that aren't there?

 

wow, starter spray is HIGHLY flammable, I would never be spraying that all over a running engine, could go ka-BOOM in your face.


anyways, unless you have a pulsair B230FD, the only thing your california car has that most don't have is an EGR, and thats just 2 extra vacuum hoses, plus the EGR controller, actuator, and valve, and the plumbing.

on the last couple years of 940's, they brought back the pulsair system, which is kinda ugly... its this weird double rubber tube over the top of the front of the valve cover, it uses vacuum pulses to pulse-push air into the exhaust ports. its very simple, it works fine, but, when the one way valves on the exhaust ports die, the big double air tube thing burns through. I have never had one, but I hear you can remove it all and plug all the ports, and the engine won't know the difference, but your hydrocarbons might be a bit high.

all post k-jet B230 engines in 2/7/9's are gonna have vacuum lines to....

• fuel pressure regulator
• idle air control
• power brakes
• heating/ventilation
• cruise control if equipped
• EGR if equipped
• carbon cannister

and probably some stuff I forgot. turbos have the boost controller.

 

Started with a cool engine. Didn't let too much build up at any one time. Starter fluid has been used for decades. Only every once in a while does some moron loose an eyebrow.

A healthy respect for dangerous things, is one thing. Total avoidance out of overwrought fear, is another. If I avoided everything because it might be dangerous if I didn't pay attention to what I was doing or plan ahead, then I would still be living in my parent's basement.

If you know anything about me from my posts, it is that I plan ahead and do things carefully.

 

Not so hard to find vacuum leaks: first, listen, a big leak will hiss. The b230 motor is mercifully simple and there are not so many hoses after all. The leaks could come from hoses attached to the intake manifold or the manifold itself where it bolts to the head. Just examine those hoses, follow their routing, I'd make sure the bolts are tight, the manifold gasket visibly intact.