s14 sr20det inaccurate boost readings - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

unplumbedNZ · 01-05-2018, 09:37 AM

Hi everyone, new here.

I've got a s14 sr20det and im having some issues getting an accurate boost reading. The boost gauge is running from one of the vacuum ports under the throttle body at the intake manifold. I got it tuned only 2 months ago on 19psi but the tuner said that my boost gauge is reading inaccurately, reading 16-17psi instead of 19psi full boost.

It's got a GFB manual boost tap supposed to be bleeding to 19psi to open the wastegate

I have tried it under load in all gears and only get upto 16-17psi in 2nd 3rd and 4th gear.

I have tried replacing the Vacuum line and tried 2 different boost gauges and got the same reading of 16 maybe 17psi at full boost.

I don't know much about the tuning side but it was tuned with a Nistune board on the factory ecu I believe,

What I want to know is does the factory boost sensor give a psi reading to the ecu therefore getting a different boost reading to the boost gauge?

Does anyone know the most accurate vacuum source I should tap into to get an accurate boost reading? would it hurt to take off the vac line to the factory boost sensor and run my gauge of that to test for a better reading? or should I try Tee off the fuel pressure regulator, is this a safe place to Tee off long term?

Essentially I need to get an accurate boost reading to ensure whats going on, if it is only making 16 psi then I can wind it back up no troubles but I don't want to wind it up if its reading inaccurately and risk leaning it out.

Has anyone had any experience with GFB manual boost taps slowly reducing the amount of boost its bleeding?

Any insight appreciated, I'm stumped

cheers.

nisileighty · 01-05-2018, 09:42 AM

Run a boost source from one of the under plenum vacuum sources. The TB ones are too small in my experiences

Sent from my iPhone using Tapatalk

unplumbedNZ · 01-05-2018, 10:00 AM

I have tried that that's what im currently running at the moment for my boost gauge, will try tap into the FPR tomorrow to see if theres any difference

ANDY black s13 · 01-05-2018, 07:19 PM

there are 2 small connectors under the TB one is pre throttle and no good,
other is post throttle and will give best vac reading,
delete the OE boost solenoid completely
just run line from turbo compressor/boost source signal to GFB boost valve thingy
> wastegate actuator, don't run any lines to the OE solenoid
BEFORE TESTING WIND THE VALVE BACK OFF,as it may spike like crazy/over boost with direct line

01-05-2018, 09:37 AM	#1
unplumbedNZ Join Date: Jan 2018 Location: New Zealand Age: 27 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	s14 sr20det inaccurate boost readings Hi everyone, new here. I've got a s14 sr20det and im having some issues getting an accurate boost reading. The boost gauge is running from one of the vacuum ports under the throttle body at the intake manifold. I got it tuned only 2 months ago on 19psi but the tuner said that my boost gauge is reading inaccurately, reading 16-17psi instead of 19psi full boost. It's got a GFB manual boost tap supposed to be bleeding to 19psi to open the wastegate I have tried it under load in all gears and only get upto 16-17psi in 2nd 3rd and 4th gear. I have tried replacing the Vacuum line and tried 2 different boost gauges and got the same reading of 16 maybe 17psi at full boost. I don't know much about the tuning side but it was tuned with a Nistune board on the factory ecu I believe, What I want to know is does the factory boost sensor give a psi reading to the ecu therefore getting a different boost reading to the boost gauge? Does anyone know the most accurate vacuum source I should tap into to get an accurate boost reading? would it hurt to take off the vac line to the factory boost sensor and run my gauge of that to test for a better reading? or should I try Tee off the fuel pressure regulator, is this a safe place to Tee off long term? Essentially I need to get an accurate boost reading to ensure whats going on, if it is only making 16 psi then I can wind it back up no troubles but I don't want to wind it up if its reading inaccurately and risk leaning it out. Has anyone had any experience with GFB manual boost taps slowly reducing the amount of boost its bleeding? Any insight appreciated, I'm stumped cheers.

01-05-2018, 09:42 AM	#2
nisileighty Zilvia FREAK! Join Date: Feb 2016 Location: Seattle, WA Posts: 1,218 Trader Rating: (4) Feedback Score: 4 reviews	Run a boost source from one of the under plenum vacuum sources. The TB ones are too small in my experiences Sent from my iPhone using Tapatalk

01-05-2018, 10:00 AM	#3
unplumbedNZ Join Date: Jan 2018 Location: New Zealand Age: 27 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	I have tried that that's what im currently running at the moment for my boost gauge, will try tap into the FPR tomorrow to see if theres any difference

01-05-2018, 07:19 PM	#4
ANDY black s13 Zilvia Member Join Date: Mar 2012 Location: erith kent england Age: 56 Posts: 153 Trader Rating: (0) Feedback Score: 0 reviews	there are 2 small connectors under the TB one is pre throttle and no good, other is post throttle and will give best vac reading, delete the OE boost solenoid completely just run line from turbo compressor/boost source signal to GFB boost valve thingy > wastegate actuator, don't run any lines to the OE solenoid BEFORE TESTING WIND THE VALVE BACK OFF,as it may spike like crazy/over boost with direct line