Is my boost gauge wrong?

[Who Needs 8]

So, when I make a WOT run, my boost gauge will say it's running 20psi but my boost harness on the Turbo-Link says 25-26 psi I am having some knock issues, but if I turn it down to where the gauge says 17PSI, the knock goes away (on 104 or 110) but the TL says 24-25 PSI.

Sometimes when it's on 93 octane and the gauge says 17 psi, I have Knock. Which makes me think the gauge is wrong. The gauge was on the car when I bought it.

Which do I believe?

 

[72firebird]

What kind of guage? If stock it could be wrong. If not, check the line connections. The Turbolink should be right since it hooks up through the MAP reading and just changes the voltage reading of the MAP to an acutal pressure value. Your TL should be dead on so I would judge off of it. I've never heard of a 3 bar MAP going bad but anything is possible.

What turbo and injectors are you running? If stock then the TL values make sense with your knock readings.

 

[Who Needs 8]

I guess some more info would help, huh? :biggrin:

AutoMeter Boost Gauge
38 lb/hr Fuel Injectors
21° Timing
Precision Industries GT 3255 Turbo
Tial external wastegate with adj. boost controller
Vigilante, 3,200 stall

The 3BAR Map is brand new.

 

[72firebird]

I guess some more info would help, huh? :biggrin:

AutoMeter Boost Gauge
38 lb/hr Fuel Injectors
21° Timing
Precision Industries GT 3255 Turbo
Tial external wastegate with adj. boost controller
Vigilante, 3,200 stall

The 3BAR Map is brand new.

In that case just check all connections to vacuum block, MAP, and boost gauge. If you don't find anything then see if there's anyone in your area that'll let you try out another gauge and see if it reads any different than yours.

 

[Lee_Burough]

I've read where Ken Mosher always reminds Tlink users to recalibrate the boost harness each time you use it. If you've calibrated the boost harness, I'd believe it.

 

[Razor]

How old is the autometer guage and tubing to it. I have seen where the plastic tube gets brittle and leaks air. A mity-vac hooked to the plastic end in the engine compartment will confirm if its leaking air.

The stock boost guage on the TTA typically is pretty accurate. As to the T-link deal..dunno.

Mechanical guages are typically correct.. assumming no air breaches to them.

 

[Who Needs 8]

Just wondering, what should the idle vacuum reading be on the boost gauge?

 

[NJVetteGuy]

With the car off, make sure the gauge reads zero. If it doesn't, the gauge is bad. I've had 2 autometers do this to me lately They read between 5 and 10" of vacuum with the car off.