I am hoping someone can shed some light on my situation.

I installed an Autometer boost/vacuum gauge a while back to replace the MR gauges the previous owner had in there. After installing, the gauge read somewhere around 5 in. Hg. give or take. I used the hose from the previous install not the one that came with the gauge. Maybe I should if nothing fixes this problem.

I thought that was kind of low so I went ahead and visually checked all my hoses, none of them had popped off. I also checked all my intercooler clamps to see if that would help and some of them were really loose, so I tightened them. After I did that, my vacuum now reads 0 in. Hg. Last night I did a vacuum test and carefully sprayed all the vacuum lines and around the intake, and idle did not change, nothing funky happened. Am I missing something here? Is this something worse? Compression?

I should mention, idle is fine nothing odd happens. Every so often it will almost stall, and then come back to life so that's definitely a vacuum issue. Help!

 

Mine just started doing the same, I am going to do a boost leak check and track down my vac leak. Hope this fixes my issue. I would start with those basic checks. Pull your vac lines and make sure none are cracked or have pin holes.

 

let me know how it works out for you. anyone else chime in?

 

Manifold vacuum is created by the engine running and creating a vacuum against the closed throttle plate. A boost leak will cause the mixture to be off because the amount of air measured won't be the amount entering the engine but it won't cause manifold vacuum to be low. Well, I guess the throttle shaft itself could be leaking.

 

Barneyb is right, even a loose intercooler clamp wont change the vacuum, it will affect the air/fuel ratio, but it wont affect the vacuum unless the leak is behind the throttle plate or anywhere connected to the intake manifold.

Follow your line and see where it goes and go from there, it prob hooks to the fuel pressure regulator line or something.

 

I just did my boost leak test and found a leak at the throttle body seals. Ordered some new ones, will let you know if it helps any.

 

is it a common thing, for tb seals to wear on these engines? I'll check that tomorrow as well.

 

okay i need help..my car idles fine but when i rev it sometimes it comes below my 1100 rpm target and tries to die and this also happens when im driving the car at low rpm or when i come to a stop! what could be the reasons? i did a boostleak test and everything seemed fine what else could cause this?

http://www.youtube.com/watch?v=jwcVh8i_8Vc


at 27 seconds you can see the car almost struggles to hold rpm...

could you all plz give me multiple reasons so i can do all of them and see..

 

Before someone else says something, make your own thread so you're not hijacking wazmustr's thread. You're running RICH though, you should not be at 10:1 AFR at idle, it should be in the 14's. That gauge maxes out at 10 so it might even be under 10. Start your own thread and list how much vacuum and all your mods it's got too.

As for the OP, yeah the tb seals are very well known to leak, mine were dryrotted and leaking pretty good. I forget his name but it's "milspec" or something like that sells milspec seals which are heavy duty seals and not supposed to leak over like 75psi, like less than 20 bucks shipped and not too bad to install, there are tutorials on here on how to change them, but if you're not confident I would buy two sets, I messed up my first one till I taught myself a trick on how to install them square and straight in the bore.

 

okay im sorry i hijacked someone elses thread i didnt even know what that is...i'll make a new thread and secondly im not running rich my afrs are at 14.7-15.0 tops whenever i rev the car it goes rich!

 

cool ok I'll check the TB seals on my next day off. Is it possible for my vacuum to be that much off with dry rotted tb seals? I mean it's straight up 0 in. Hg.

 

No - or very unlikely.

I've been thinking ever since you first posted that there is something wrong with your gauge.

 

I fixed it! Nothing wrong with the gauge. Like everything else that has been wrong with this car, the previous owner(s) half assed the mr gauge job and used a hose that was way to wide in diameter. Since I got rid of those gauges I used that hose. Well I finally decided to replace it with the one that came with the auto meter gauge, and tada! 15 inHg. The hose was even routed outside of the engine bay through the fender then back into the car. I will never buy an evo like the way I did ever again. Lol