Superchager Woes

I have a 2000 VX with what I believe is an Alpine supercharger. Anyway its an Eaton M62. I was just rebuild and has a new pressure release valve. My problem is no boost :confused:. I installed a vacuum/boost guage. I get -20 on idle. Full throttle I get 0. When I blip the throttle I see the pressure release valve close momentarily and reopen and stay open. When I floor the throttle it does the same thing. I looks like there is not enough boost to allow the valve to close or too much vacuum. There may be a problem with the the way the vaccum lines are run. I have all the lines after the charger connected together (Fuel pressure reg, release valve, and intake manifold) and every thing pre-charger connected. Does anyone have clear picture of the vacuum/boost routing on a Alpine system?

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Originally Posted by shinkson

I have a 2000 VX with what I believe is an Alpine supercharger. Anyway its an Eaton M62. I was just rebuild and has a new pressure release valve. My problem is no boost :confused:. I installed a vacuum/boost guage. I get -20 on idle. Full throttle I get 0. When I blip the throttle I see the pressure release valve close momentarily and reopen and stay open. When I floor the throttle it does the same thing. I looks like there is not enough boost to allow the valve to close or too much vacuum. There may be a problem with the the way the vaccum lines are run. I have all the lines after the charger connected together (Fuel pressure reg, release valve, and intake manifold) and every thing pre-charger connected. Does anyone have clear picture of the vacuum/boost routing on a Alpine system?

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Worry not my friend...unca dub gotcha back...:yesgray:

http://www.vehicross.info/gallery/da...ac_routing.jpg

Hope that is of some help, I seem to remember that it was the missing piece of the puzzle when I experienced the same problems as you currently are.

Also I remember that the boost gauge would only register boost if hooked to a certain vac line, but right now, I don't have time to clarify.

Gonna be outta town for the weekend, so if this doesn't do it, I'll take another whack at it Monday...:yesgray:

Yeah, I saw that pic. The only question I have about that pic is " where is the vacuum canister?" I have that line going to my vacuum manifold block. I will take a picture this weekend. Hopefully that will help you help me. So you had a no boost issue before? If so that would be good news since it sounds like you found a fix for your issue.

IIRC, the vac canister is looped. Basically, plugs into itself. If we are talking about the same thing that is. See diagram: (#10)

http://www.vehicross.info/gallery/da...onnections.jpg

Yeah thanks. I saw that diagram also. My vac canister is looped. My query is related to the port labeled vac canister on the throttle body monifold or supercharger intake. See attached pic.
https://dl.dropbox.com/u/46799264/vac_routing_1.jpg

I'm going to concentrate on the boost bypass valve which fails to close on WOT. I just realized that no matter what else may be wrong, there will be no boost until that is closed. I also don't think I have a leak because I am getting about -20 vacuum on idle and about 0 on WOT. That seems to be in line with a normally aspirated engine. So I will disconnect and plug the vacuum line going to the bypass valve and leave the valve open to atmosphere. This will shut the valve. At this point giving it a little throttle should result in a quantifiable amount of boost. Fingers crossed.

Have you driven it when testing? You will get no boost unless you have a load on the engine.

Yeah I've driven it to work a couple of times. GUTLESS!

FWIW, my boost gauge is t'd into the FPR vac line, & reads boost...:_wrench:

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Originally Posted by Ldub

FWIW, my boost gauge is t'd into the FPR vac line, & reads boost...:_wrench:

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+1

My old gauge would not read anything over 0psi under full load. Ended up the S/C was creating boost, the gauge was just borked. New gauge, all has been good since.

Hmmmm, I'll try changing the gauge

Well, I changed the gauge and got the same results. The vx runs fine, just no extra power. I live in Utah so finding anyone with hands on supercharger experience is difficult. Any other suggestions?

I connected my ODBII sensor for my work commute and validate that I am getting 0 boost. Does anyone know any good machanic shops in the Ogden UT area

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Originally Posted by shinkson

I connected my ODBII sensor for my work commute and validate that I am getting 0 boost. Does anyone know any good machanic shops in the Ogden UT area

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IIRC, the stock sensor will only measure vacuum, it wasn't designed to measure boost.

Maybe try removing the S/C drive belt to see how much difference there is.

What Dub said, I don't think it will reveal data over OEM load. I tried my ScanGauge once as well and it didn't reveal any added load though my gauge was showing boost.

I did this wrong first up too!
The valve should 'spring closed' with nothing attached to it. The vacuum line needs to come off the maximum depression area just behind the throttle body. Your gauge should be on the manifold after the SC.
Set up like that my vac/boost gauge needle follows my foot position

Sorry Robbomaz, I have been hibernating for the winter. Too cold to screw with the vx til now. I was re-reading the thread and your comment about the vacuum line stood out. Where is the maximum depression area? Any pictures? Are you talking about number 4 on the diagram?

The Isuzu throttle body itself has some vac ports. The maximum depression is just on the engine side of the butterfly. I found the best result came when using one of those.

Hibernating for the winter? That made me LOL! Here on Oz we stay inside during the height of summer!

Great! thanks Ill try that on the next warm day. I currently have it coming from the manifold that the supercharger sits on. Post supercharger.

Boost gauge and fuel pressure reg feed go there
Bypass goes on a vac port on the TB