Boost Gauge HELP!!!

[David Carter]

ok..first off.. no rush..nothing completely urgent..i got the car back running.

Second never work on a car when your impatient..you break stuff and only get mader..

I bought a set Autometer A/F meter & Boost Gauge from A&A Auto in Allentown, PA.. paid 137.00 for em.. not bad i think.. i know i could have shopped around.. anywho i decided to put them in now so i wouldn't be to over burdened when i do the saab intercooler install..(which all i'm waiting on is the Rallitek Turbo Intake) that and i'd be better off with boost gauge to be installed before i install the MBC..

Now it has taken me now 7 hours to come to a point where i can say i'm finished....for now.. I got them installed.. i've learned some valuable lessons, and i now have to have some things replaced because of such valuable lessons.

Never take apart a dash with a hayes manual..nor when impatient..got that apart, started to run the wires for the A/F and the boost meter hoseing out thru the Fire wall toward the engine, I would work on the engine while my friend worked inside the car. I installed the Boost gauge first as that was fairly straight forward. i tapped the boost gauge here:


Now where i make my first mistake, i visually find the O/2 sensor and by eyeing it follow a shielded cable to the firewall where the wire bung is. I'm thinking thats GOT to be the O/2 sensor wire with all that shielding.. after 10 min of tring to cut thru an outer sheth, an steel braided sheth, and a plasticoating, my friend asks me why i'm cutting my speedo cable, i assured him completely that it was the O/2 sensor cable..he again tried to worn me, but i shooed him away and continued trimming away...another 5 min later..and a whole lot of cussing.. i finally cut thru what is my speedo cable... DOH!!! first mistake of the day down...

so with my friend help he easily points out the 3 wires attached to the o/2 sensor we tap the white signal wire and are both back inside..one of us a bit more humble, and bit more impatent.. we finally get everything wired and start up to a very sick car.. for a half hour i couldn't figure out why the car was running on 2 pistons.. lots of white smoke and an very rough idle/accel a ruff everything... we take a break and eat.. and come back with fresh heads.. well we attach the ground wires we forgot about and the O/2 sensor finally gets to talk to the rest of the engine and all is well.

Now why did i make you read all this. My boost gauge is not working properly. It reads vacume, and like 5psi of boost no matter how much i'm flooring it. Yes i have boost, at 2500 it spools up giving me a nice ride to 6000 and a smile on my face but the boost gauge won't show me any spikes, or anything over 5psi? do i have a leak? some of the stock pipeing is mighty old, and crusty..? Did i pick a bad spot to tap the gauge? the guys at Rallitek told me as close to the throtle body as possiable..










Would a slight crimp or bend in pipe here make the boost gauge read wrong..

Thanks for any help you can provide. i hope you all enjoyed my little experiance..and learned to be a bit more patient

David Carter

[Hondaslayer]

Get rid of that crappy Vinyl tubing and run straight vacuum line to the back of the gauge.Look for the fitting with the smaller threads and foce the vaccum line over it (going into the gauge) your readings will be more accurate and much faster.




Ben,

[legacy92ej22t]

You put your gauges almost exactly where i'm planning to do mine! Kind of a trip cause I haven't seen anyone else here with them there and was going to do it this next week. I think i'm going to go with single pods though, that way I can do them one at a time. I'm going to put my boost gauge just to the right of the steering wheel and keep moving to the right with the rest towards the passenger side dash. I don't know for sure but I thought the best place to T in for the boost gauge was on the line from the intake manifold to the pressure exchange solenoid.

[vrg3]

Wow, man... Sorry to hear of your epic saga. Did you get a new speedometer cable?

Most people tap the oxygen sensor signal near the ECU rather than in the engine bay. If you need a reference to the ECU pins, look here:

http://www.graphics.cornell.edu/~v/ecupins/

The vinyl tubing should be okay if it's not too long... It will slightly affect your boost gauge's response time but I can't even notice it on mine. It doesn't affect accuracy. A small crimp would worsen the response but still wouldn't affect the accuracy (unless there's a leak).

About the reading ... The line you tapped is the one coming from the charcoal canister purge control solenoid. I don't think it's ported vacuum but it may be. The place I usually recommend tapping the vacuum lines for a boost gauge (as Matt suggests) is where Morgie did here:

http://www.graphics.cornell.edu/~v/pics ... ge_tap.jpg

That is where the pressure sensor signal originates, so as a bonus you'll see the same signal the ECU does.

But you may really only be making about 5psi of boost. 5psi is usually still enough to put a smile on peoples' faces. If your boost control solenoid is failing (a frequent problem after about 12 years), your boost level will be controlled entirely by the wastegate spring, which is set to 5 or 6 psi. An aftermarket manual boost controller is usually the simplest and cheapest solution to this.

[LegacyT]

Like Vrg3 said the little nipple on the front passenger manifold leg is best to tap. This probobly has been said too but the plastic tubing that comes with the autometer guage isn't as good as true vaccum line. My guage is both quicker and more accurate I was reading over 1 psi higher with good vaccum line.

Mark,

[vrg3]

Mark, you must have had a leak somewhere before the vacuum line joined the nylon tubing... Otherwise the reading would not have been lower with the nylon tubing.