r34 rb26dett boost issue

[hybridracer504]

So the problem I'm having is that my stock boost gauge on my mdf screen is reading 0.6 bars at idle. I started having the problem after i replace my throttle body and intake manifold gaskets and slightly cleaned my throttle body. I know i shouldn't have cleaned them but i stopped after i read that you shouldn't but my idle isn't high at all. Only problem I'm having is the guage reads boost at 0.6 bars at idle.  i also have a greddy profec that reads -0.5 bars at idle thats hooked up to a mac controller. The controller is hooked up with one hose to the intake plenum near the idle air control valve and the other on is somewhere's else. Its really hard to see and i didn't add the controller or greddy. It was on there from the previous owner. Please help, I'm stumped and don't know what else to do. I'm new to this so please go easy on me...thanks in advance.

Edited April 9, 2019 by hybridracer504

[Duncan]

That is a bit strange, because that just comes from the MAP sensor on the firewall near the brake master cylinder.

Does it work OK when you start to hit boost (ie, does it match the greddy gauge when you are driving)?

I'd start with swapping the MAP sensor for another one to see if it has failed somehow, otherwise there may be some issue in the wiring. The air source is unlikely to be the issue since it is reading high, but you can check the air line is connected to the back of the plenum and has no cracks or splits

[GTSBoy]

2 hours ago, Duncan said:

but you can check the air line is connected to the back of the plenum and has no cracks or splits

Is not the GTR boost gauge MAP sensor supposed to be connected to the little plenum that taps into the intake runners downstream of the throttle plates?  How would it ever read vacuum if it were not?

[Duncan]

57 minutes ago, GTSBoy said:

Is not the GTR boost gauge MAP sensor supposed to be connected to the little plenum that taps into the intake runners downstream of the throttle plates?  How would it ever read vacuum if it were not?

Agreed....it should be on the manifold (post throttle), not plenum (pre throttle)! Been too long since I've run with one attached. Either way it is not clear to me how it could read higher than atmo unless the problem was electrical not mechanical

[GTSBoy]

Yuh, sensor or gauge is f**ked.

Sensors are piezoelectrical.  Hit them hard enough (physically, or electrically) and they will die.

[RBW49N]

Could something be stuck in the line causing it to hold air after it got pressurised

[GTSBoy]

What?  An accidentally installed check valve?  It does change upwards when you boost it, yes?

[hybridracer504]

I don’t know...it was working fine before I replaced the gaskets. The greddy profec is tapped into the same vacuum line as the sensor. I’ve unplugged the vacuum line for the greddy and it still doesn’t change. I’ve tried driving it down the street but I’m afraid to get on it. Both of the gauges read different. The stock one on the vehicle spikes all the way to 1.2 bars when I tap on the accelerator. What are the ohm readings for checking that sensor? I just don’t want to throw parts at it and not fix the problem 

Edited April 10, 2019 by hybridracer504

[GTSBoy]

Don't worry about the stock gauge.  It's clearly stuffed.  Trust the Profec.