Hey I'm in the middle of an install of a boost gauge and i got the thing wired up but I can't figure out why I'm not getting any reading from the gauge. The wiring for the lights is good but no reading. I don't have the supercharger on yet but the gauge should still read some vacume telling me that at least its working. I looked in the install pages and on Lancershop.com but that was for an 03 and taped into the FPR vacume line. I have no FPR except for in the tank so were is the vacume hose on my car?

bump

and i'd like to add that i taped into the line that i used to use for my piggyback. So maybe I've always had it installed wrong too

help please

last bump of the night

im not sure how the 04s are set up, but you should tap into the vacuum line coming off of your intake manifold with a T fitting. on the left of the manifold is the line that needs to be tapped. try that.

Is that the one welded to the top of the intake mani? that goes to the cruise controll housing.
This is where I hooked it up initially. And can't get a reading

this line right here that is circled

Thanks imapunkclaimer for the pic but the 04 is a little diffrent. However I T-ed into the one that is just after the throttle body and I got a vacume reading from the gauge. If anyone reading this sees this as a problem please let me know.

I guess this means that my piggyback was installed wrong the whole time too

That should be sufficient for a vacuum reading. Is that the line RRM tells you to tap into? There should be a vacuum line coming off the stock fuel pressure regulator that you can tap into. If you look at the picture, the FPR is the gold circular looking thing to the lower right of the big red circle in the picture. There is a vac line going on to that and you can tap that (although, again there are the differences between the 04 and 05).

If you are getting a vacuum reading, then you should be good to go for both the gauge and the piggy, otherwise, call RRM and ask them.

best place is the line from the manifold to the fuel pressure regulator, its going to be very accurate as well.

Thanks guys for the info. I taped into the line starting at the IM side of the throttle body. This seems to give an accurate reading about -10psi when idling or coasting and -1 to -2psi with wide open throttle.

Vacuum is not measured in PSI just for your information. It's "in. hg", which I have no idea what it stands for.

-10 doesn't sound like enough vacuum, on my Lancer I was at -20 at idle, but I had a turbo, so maybe that produced more vacuum?

Don't know When accelerating at Wot, mine reads a big flat 0. Which most likely means the pressure inside the Intake manifold is equal to the atmospheric pressure Meaning the engine is not s*cking air in. The atmosphere is just stuffing it in since there is no in/out restriction.


in.Hg = inches of mercury

Don't quote me on this but I think: The higher the number(in vaccum reading), the more the engine is forcing to s*ck the air in. At low Rpm, when the turbo is not pressurizing the Im the engine as to s*ck in with more force because the turbo inlet is smaller than a regular intake. Just like the straw example. If you s*ck air from a straw, it takes you more force to suck in the same amount of air creating a bigger vaccum measure than if you were s*ucking air from a 3" pipe.

u should be around 20 in the vacuum side at idle, turbo or no turbo and at 0 at wot for non turbo of course. and drop to around 23-26 in the vacuum, off the gas in a gear with backpressure.

Inches of Murcury huh, with a college education you think I should have figured out what "Hg" was.

Sounds like you might have a vacuum leak somewhere. Double check ALL of your vac lines, and make sure to zip tie the tee fitting and at the gauge, so the lines don't come loose.