Jump to content
SAU Community

Recommended Posts

hi im new to my skyline

what does this stock boost gauge mean?

doesnt +7 supposed to be 14psi?

mine only goes over the "0" just a tiny bit even though i did that mod where you can undo and leave your car running 2nd stage stock boost all the time

so is mine supposed to be like that on the stock boost gauge or is there something wrong?

Link to comment
https://www.sau.com.au/forums/topic/110844-stock-boost-gauge/
Share on other sites

start with checking the hose to the boost guage.. it is located in the drivers side rear of the engine bay, right in the corner. hose comes from the back of the plenum.

if thats ok, check all the hose clamps on the intercooler piping.

try to test with an aftermarket guage.

ummm something seems to be wrong. 7psi should be in the middle (which is what you should be running if you've bridged the solenoid to leave it permanently high boost) of 0 and 7mmHg.

You're right, 7mmHg = 14psi. Boost leak somewhere??

0 is "atmospheric" pressure. -7 is vacuum , +7 is boost. And I'm sure there are posts around suggesting that the scale on the gauge is "x 100mm Hg", so the range is from -700mm Hg - 700mm Hg (760 is 1 bar or 14.7 psi)

ALL engines cruise under vacuum, so your car should always have the boost gauge sitting between -7 & 0 under normal driving conditions. Only when you hit boost should the gauge indicate a reading > 0.

Now back to the original problem - if the car feels like boost is working, then it is obviously a leak between the manifold and the gauge. If it feels like boost is not happening, but you can here the turbo working, then it is a problem with the plumbing between the turbo and the inlet manifold (slipped connection usually). If it feels like boost is not happening and you can't hear the turbo, then it's likely a dead turbo (probably blown exhaust wheel).

ALL engines cruise under vacuum, so your car should always have the boost gauge sitting between -7 & 0 under normal driving conditions. Only when you hit boost should the gauge indicate a reading > 0.

I've always wondered, is it best to cruise with more vacuum (closer to -7) then it is to cruise closer to 0... Will more fuel be consumed under less vacuum?

Just been wondering that for a while... anyone?

fuel consumption is based on the stock ecu using its factory closed loop feedback. it doesnt have anything to do (that i know of) with boost pressure. as the fuel injection values off the maps are based on engine RPM and airflow meter load, not boost pressure.

fuel consumption is based on the stock ecu using its factory closed loop feedback. it doesnt have anything to do (that i know of) with boost pressure. as the fuel injection values off the maps are based on engine RPM and airflow meter load, not boost pressure.

Wouldnt more vacuum mean theres greater flow past the Air flow meter?

I dont have a clue when it comes to this, just making wild guesses :laugh:

The vacuum is behind the throttle plate. The air flowing in past the throttle plate to "fill" the vacuum is controlled by the position of the throttle plate. At a high vacuum - closer to -7 - less air can flow past the throttle plate (small throttle opening), so less air is flowing through the AFM.

Less vacuum actually equates to more AFM airflow due to the wider opening of the throttle plate.

You can only cruise at a given vacuum given the condition of the engine - to vary the vacuum, you need to change the throttle plate position, so you change speed, so you aren't "on cruise".

If you study the maps in any programmable ECU (PFC, etc) you will notice that the injector times at low loads (high vacuum) are much shorter than those at higher loads (less vacuum, or boost).

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...