Low Vacuum, Ideal?

[jukematt]

This is for my 99 GSX. Whenever my car is on, whether cold or warm, my vacuum sits at 5 hg at idle. I can boost fine (still stock level). It used to be about 15 before my clutch got replaced. I did find a boost leak by my smic so thought that was the cause but after I replaced the stock tube with all steel upper and lower, no change.

Does anyone know what causes the vacuum to be so low?

What is the ideal vacuum pressure?

I do know that there's a wiring issue with them lighting up and the EGT doesn't even work correctly but the boost gauge is mechanical. Suggestions? Thanks.

 

[jukematt]

misterjose: I will check that thanks.

agentorange313: What is that device being used to check the IAC/ISC? And where do I get it? And what is a BISS screw? Sorry I'm still learning.

 

[aPOS]

misterjose: I will check that thanks.

agentorange313: What is that device being used to check the IAC/ISC? And where do I get it? And what is a BISS screw? Sorry I'm still learning.

The "device" in agentorange313’s video is a digital multimeter. Walmart sells these.

This site will help you learn the parts on your car. This shows the BISS, yet you can use this site to learn about other parts on your car.

http://members.shaw.ca/dsm.1000q/Eng...er/2G/biss.htm

 

[jukematt]

OK I got a digital multimeter from Walmart. If I had it on the right setting, I was getting 40 ohms on each set of two I checked. The video says 28-30 is good but has seen more and is OK.

Well, after changing my spark plugs and reconnecting a hose that I have no idea what it was for but plugs into the intake (See this thread: http://www.dsmtuners.com/forums/electrical-tech/397765-wire-under-battery-not-plugged-what.html), the idle is back at 5 again. ): I wonder if my timing is off. I plan on getting my timing belt and components replaced when summer hits. I don't know what else is going on.

Thoughts?

Also, not sure if this is related, but my idle is about 500 rpm now too

 

[twotall]

boost leak test try this http://www.dsmtuners.com/forums/art...-boost-leak-test-how-boostpro-net-tester.html

 

[jukematt]

OK I'll build a tester and check the system. I didn't think that a boost leak would cause my problem but we shall see

 

[jukematt]

OK so I was driving around a LOT today searching for the parts to build this boost leak tester:
YouTube - Boost Leak Testing 101: Building the tool.
I liked it since it had a gauge and that the gauge was detached from the rest of the tester. Well I went to Autozone, Schucks (O'Reily's), Home Depot, Big R, Napa, back to Schucks. I was having a really hard time finding the parts but I think I got everything that will work; I just have to build it.

Well back to my point I was going to make. My boost gauge slid out of the a-pillar pod it is in as it was not tight in there. When it slid out the level dropped to 15 inHg. I pushed it back in and it went back to 5. Pulled it out far and it dropped to 15 again then leaked (I could hear the air). So I guess it was not connected right. This really isn't surprising considering the mess of wires done by the previous owner to install them. I'm planning on getting the new gauges over the summer. I could fix these but I don't like the color scheme of them anyway.

I'll still run a boost leak test once I get the gauge made but for now at least I know the problem of the vacuum pressure. Of course I do still need to figure out how to get the proper tool to fix my idle. I'm at 500 rpm currently.

 

[jukematt]

Well the gauge stopped working completely and I don't like going without a boost gauge so I pulled it out and a kink in the line caused it to break. I cut it past that point, fixed the gauge, and now I idle at 21

I also ran a boost leak test and the gauge on my tester didn't work (though I used a 1/8 size instead of 1/4 like in the video but that shouldn't matter. Anyway, I found a leak somewhere around my turbo but couldn't find exactly where it was. My friend said he has found one around the housing with another turbo or it could be a gasket. It's not bad but it's there. I'll probably look closer over the summer after school.