Boost gauge is kaput

[pvt num 11]

Like I said, the factory gauge doens't read anything but zero, but I know the car is making boost - I walked my L98 GTA last night! Does anyone have a neat little guide on how to troubleshoot these things, like, is the gauge a mechanical or an electrical unit, could it be the sensor, ect, ect, ect.

 

[mark b]

I apologize in advance because this doesn't directly answer your question, but.... the factory gauges are notoriously inaccurate anyway. I'd recommend an aftermarket boost guage - most of us have put one in anyway.

If you don't want to do that because you want to remain 100% stock, I can respect that!

 

[Johnboy]

Boost Gage

Check the post below. I spent considerable time getting mine to work and be accurate. Let me know if you have any questions.


http://turbobuick.com/forums/showthread.php?s=&threadid=137252

 

[pvt num 11]

Thanks, I'll have to toy with that tonight when I get off work. Anyone got pictures of the MAP sensor? (MAP and MAF? )

 

[mark b]

The "MAF" is the 2.5 inch sensor on the air intake system to the plenum. Don't touch that

The "MAP" should be on the fender...look for a hard plastic vacuum line from the intake area to the sensor on the fender. I haven't seen my TTA in a long time, so I'm thinking how it is on my GN.

 

[pvt num 11]

Oh, I knew what they were , I'm just surprised that the car comes with both, usually you have a MAF car or a Speed-Desnity car, using a MAP, instead.

 

[Lunkan]

Originally posted by pvt num 11
Oh, I knew what they were , I'm just surprised that the car comes with both, usually you have a MAF car or a Speed-Desnity car, using a MAP, instead.

If I got it correctly, the MAP-sensor is only used to measure boost.

 

[pvt num 11]

Aha, I get it... So the MAP is what sends the signal to the gauge, so either I have a bad wire inbetween them, or a gauge, or worse - the MAP. Or the easierst of them all, some wag disconnected the gauge behind the dash. I'm really not fond of ripping Firebird dashboards apart, too...

 

[1badTTA]

Yup, correct. The sole purpose of the MAP sensor (3bar on the TTA's) is to run the gauge. It isn't even connected into the ECM.

 

[pvt num 11]

I took a peak under the hood, found what you all were talking about, and there's a vacuum line running form the MAP - goes to a tee fitting or something, and one end of that tee fitting was unplugged from another line, that went to the vacuum block. The line looked kinda trashed, but I stuck it back on anyway, and test-drove it. No real change to the gauge, but I didn't check after my test drive if the hose failed. The wires look okay, and the lil' splice connector is in place, but I don't have a multi-meter so I couldn't actually check voltages. I'll try that as soon as I can find my DMM.

 

[Razor]

If you turn the ignition on..unplug the MAP sensor.. and on the MAP plug jump the green and gray wire using a paper clip/wire/etc.. it should peg the dash boost guage. If it doesnt... you have a wiring or dash guage issue.

There should be a plastic hose leading from the vacuum tube to the MAP sensor. Any breaches(hole/leaks) wont let the sensor operate correctly.

Get a DMM and figure it out. Try and keep hoses and such as close to factory as possible. The further its from factory.. the more you'll chase your tail.

HTH


Lunkan, the 3 bar MAP also reads vacuum. 1 bar is vacuum, the other 2 bars are boost.. thats why its a 30 PSI sensor.. our factory guage only reads boost