califoreigner

stock boost gauge reads boost, but not vacuum. Anybody got any ideas?

bigdv519

iTrader: (3)

If you want to see an accurate vacuum reading, go to Atuozone and pick up a pressure gauge. Mine costs ~$15, and it works great. Old gauge used to show only 12" of vacuum at idle. Now were at a strong 19".

NZConvertible

What excatly to you mean by "doesn't read vacuum"? While cruising does it sit at zero or is it sitting at the bottom of the gauge (-200mmHg)? Below zero is vacuum.

califoreigner

Yeah, I mean no neg. Needle sits at 0 while idling. Anybody?

88turbotime

stock guage sucks. get a mechanical boost guage.

califoreigner

Before I go out and buy aftermarket I'm wondering if its a faulty gauge or if there is
actually things I can check that might be preventing it from reading accurately. I bought the car about a month ago. Only other car I've owned w/ turbo was an eclipse and I could def. feel the turbo pull in that. Turbine rotor spins freely and little side to side play. Poss. need a new hotside and wastegate actuator?

rotorforce

Here.. Problem solved

http://www.broadfootracing.com/Autom...st%20Gauge.jpg

88turbotime

yeah really i dont know if you have more problems than just your guage or not but i would get an aftermarket one anyway, because the stock ones are known to stop working and not be very accurate, and do you really know what 40 x10 mmHg means anyway?
I mean, i know what in means but no one uses that.

HAILERS

I doubt the turbo has anything to do with the gauge reading zero at idle, idle being around 750rpm give or take.

The boost sensor should be reading well below the zero mark at idle.

Try this, pull the vacuum line off the boost sensor and plug the line. Then start the engine. How close to the ZERO mark does the come???? This idea is just a twist on the factory service manual which tells you that when you turn the key to just ON, the needle should go to the zero mark. Sort of ignore that procedure and do the first thing I mentioned.

Or, heck, put a piece of vacuum hose to the boost sensor and suck. Have someone look at the gauge with the key to ON. You'd expect the needle to move below zero. Does any of that happen???

I'd be a bit less concerned with the gauge but more about what the ECU is seeing out of the boost sensor. PUt a meter on the input wire of the boost sensor at the ECU and compare it with what the FSM under Control Unit suggests as a voltage.

By the way, on my factory turboii car, turning the key to ON will not get the gauge needle to go to zero. I'll reach from dead bottomm to about three quarters of the way to the Zero mark. Plugging the boost sensor hose and running the engine will make the needle allllllmost reach the zero mark.

Again, it could be a boost sensor problem and NOT a gauge problem. See what the input signal from the boost sensor, at the ECU, is at idle/on and compare it with the FSM figures. Write back YOUR numbers and I can tell you if your even close.

88turbotime

yeah, i doubt it is the gauge itself, probably the boost sensor, but if you get a mechanical one it will definitely read right.

califoreigner

HAILERS- thanks for all the input. I won't have access to a meter until tomorrow, so I could only check so much. Sucking on the line to the sensor brings the needle all the way to -20. And w/o the car running, but the key on the needle is more than 3/4 to zero. Plugging the line leaves me at zero (or should I have plugged the other end?). What do you make of this? I did solve one of my many problems today though.
Took apart my apex bov (the only aftermarket part on my car) and found that the cylinder that seperates the chambers was stuck. Fixed it and I can hear it now- YEAH! THats what I'm talkin about! Man, I really need to get an experienced rotorhead to look at my ride. Plenty'o issues..

HAILERS

Turning the key to just ON and getting the needle to go only 3/4 the way to the zero.........mine does the same.

Sucking on the nipple TO the sensor and it going all the way to the bottom.......sounds like the sensor is working. I have never done that.

Plugging the line and running the engine and the needle goes to zero.............similar to my car. I'm not sure why that is. It's voltage related what with the alternator running.

So the above sounds normal. What does not sound normal is you say at idle the needle does not go way down to the very bottom. That is odd. Air leak in the boost sensor line????? ON my car at idle the needle buries itself at the very bottom. I'm at a loss why yours does not go to the bottom with the engine idling. It seems to work normal in the other positons.

One of these days I'm going to seperate the boost gauge's ground wire from the other ground wires (it's spliced to damn near every other sensors ground wire and ends up at the ECU........going thru the ECU to gnd. Odd. I'm goind to just run it from the gauge to chassis ground all by its lonesome. Deep down I KNOW it'll at different.