Vacuum issue and idle fluctuation

[Matheus]

Hi there guys.
Since I installed my SC Ive been facing idle issues in my car. When car is cold and i start it, my vacuum gauge is reading -9 to -10inHg. After some time, it read -12 to -13, when should be around -18inhg.
During this low vacuum period, my idle fluctuates just like you can see in the video below.
Note: i dont have any boost issue. My car makes 6psi with VF-620.
Note: i only have this vaccum issue at idle.

Idle Control Valve? Throttle actuator?



https://youtu.be/tnGQJSQor9s


Thanks in advance for any kind of help!

[Matheus]

Any thoughts guys? Someone faced a issue like this?

[Matheus]

Edit thread to make it clear

[Patrón]

I'm estimating idle control valve , but believe you should get a error code if it is truly malfunctioning.

I'm hoping that a vendor that has installed a lot of superchargers will chime-in with what vacuum ranges should be at idle. i believe it has a lot to do with altitude/amb temps/barometric pressure etc..
I think my vacuum is too low but not sure what acceptable specs are. at least your boost is normal.

[GDrider77]

Im having a similar issue, my idle is pretty much dead on AT 650, But the vacuum sits between 11.5-12. Not sure if this mild fluctuation is a concern. I really wish we could get some information from ESS or a shop regarding expected vacuum at idle? Iwas just told be ESS that as long s HP and boost are as expected then should be no worries? I am at around 5000ft elevation. Will post a video showing this soon.

[Patrón]

Originally Posted by GDrider77

Im having a similar issue, my idle is pretty much dead on AT 650, But the vacuum sits between 11.5-12. Not sure if this mild fluctuation is a concern. I really wish we could get some information from ESS or a shop regarding expected vacuum at idle? Iwas just told be ESS that as long s HP and boost are as expected then should be no worries? I am at around 5000ft elevation. Will post a video showing this soon.

I am at about 1,000 ft above sea level and on most days my vacuum is in the 12-13 range, mostly 13. on rare occasions i will go into the 14s but not too often and I think it's most if the ambient temps are very low (below 60 dg).

i am catless which i'm sure makes some difference (back pressure)

[Matheus]

Originally Posted by Patrón

I am at about 1,000 ft above sea level and on most days my vacuum is in the 12-13 range, mostly 13. on rare occasions i will go into the 14s but not too often and I think it's most if the ambient temps are very low (below 60 dg).

i am catless which i'm sure makes some difference (back pressure)

I can read those same numbers, but in my case they fluctuate. Car starts at -12 -13 range, with rpms solid at 650. After some seconds vacuum starts to get lower, and when it reaches -9 the ECU raise up my rpms to 900. In that point, vacuum goes back to 13. Rpms drops again to 650 and the same process take place. Car stays like this until the engine is hot. After that it seems to desapear.
Im located at 2800 ft above sea level. Once VF told me that i should expect something close to -20 at sea level. Would be great if someone came up with some solid information about this.

[andrewkd16]

Mine does the same thing with my ess kit. Video is pretty much spot on when cold but once car is warm no symptoms at all runs normal. Keep me posted if u find a problem or solution

[JsL]

My car run a little rougher when cold too. I have a VF540 kit.

I live at sea level and I just took my car up to 6225 feet over the weekend.

For reference:
Sea Level vacuum at idle -7inHg
6225' vacuum at idle -12inHg

The power difference is huge between the two elevations (obviously), you higher altitude SC guys need to drive down to sea level just to see what you've been missing