Need Help Now...Air/Fuel Gauge & Boost

SON240sx Automotive
1

Blacktop SR20DET in a 1990 240SX

I just purchased an Air/Fuel and Boost gauge from Varun (megan racing) and basically I need help on how to install the wiring.

Air/Fuel

  • Found the O2 sensor
  • O2 sensor has three wires coming from it: 1) Black 2)White 3)White
    what the hell do I do? It says to connect the gray wire to the oxygen sensor signal wire. But which one is that? It’s apparently between the O2 sensor and the Power Control Module. It has to be one of the two white wires (black being a ground) and I’d try trial and error except if it’s the wrong one it’ll fry the sensor.

Boost

  • what does the nylon pressure line connect directly to? It says to connect directly to the vaccume system but where do I find that?

In general

Where is the 12V Ignition Switch?
Where is the portion of the headlight wiring that i’d connect the lighted gauge to?

2

I need to know ASAP. The car is sitting in my driveway without a hood. :lol:

3

Never looked at an O2 sensor on a SR … don’t want to try and give advice there.

vacuum system = your intake. Somewhere close to the throttle body.

12V Ignition = look around under the dash around the fusebox. You’ll find a 12V ignition wire. There is also one your stereo uses you can ‘borrow’.

Where is the portion of the headlight wiring that i’d connect the lighted gauge to?
Parking lamp circuit? You can find it by the fusebox as well.

4

you can either trace the wire to see which one goes to the ECU, or you can get a multimeter, unhook the o2 sensor, start the car, and put the probes inside the connector, test all 3 wires.

I know it’s nice to think the black wire is a ground, but I’ve come across enough black nissan wires that were signals

If it’s anything like my S12, the 3 wires are ECU signal for the heater element, return signal to ECU and ground.

So without the o2 sensor connected, you should get the send signal from the ECU for the heater from one of the white wires, and nothing else.

So you know the white wire without a signal should be the O2 send.

5

“vacuum system = your intake. Somewhere close to the throttle body.”

Before the throttle body or after it?

Anyone ever installed a boost or air/fuel gauge?

6

Thank you so much, I’ll do that in the morning. A 3 way T-joint comes with the boost gauge and so I was just looking for which line to connect it into. However, I’m still looking for the O2 line to splice in.

7

Any Pics of where exactly this goes would be helpful, as I’m waiting to hook mine up too, but have no idea where to connect it!!

James

8

i did my autometer mech gauge the ghetto way, 3 way t off the fuel pressure regulator, then ran a vacume line all the way onto the back of the gauge becaue autometers kit to hook it up was gay

9

[quote=AppleSauce][/quote]

Change your damn avatar.

10

hahahah ed ur the man, i vote for ed to be new club president, ghetto way is the bomb shit… so easy to install that way.

11

teheheh you got it eh? 8)

12

K, where the hell is the fuel pressure regulator… In terms like “the big black box with a circle in it” would be nice… haha :? :slight_smile:

James

13

Another hollow victory …

14

Thanks alot AS for that Pic, I’ll try to hook it up tommorow!! btw…thats a damn fine engine bay!

James

15

Ed takes pride in his work on his car.

It did take him 2 years to do his engine swap :wink:

16

You want your boost gauge to have the strongest vacuum/boost source …

If you already have 3 or 4 lines coming off something, you won’t get a true signal.

Not that it really matters.

Intake manifold is usually one of the better sources, which is where I’m guessing the FPR gets its source.

17

Hey, now that i’ve installed my boost gauge it’s giving me odd readings?

  • when the car is off it’s at 0 (I figure this is normal)
  • when the car is idling it’s around 20? (towards the left side, counterclockwise)
  • when i’m pushing the throttle it’s around 5ish (again towards the left side, counterclockwise)

it hasn’t even gone towards the right side???

me = confused

18

thanks, it’s all good (building minimal boost due to the crack between the turbine and the exhaust manifold and KA fuel pump).

Why doesn’t my air fuel gauge work???
I’m positive I have it connected to the signal wire (the middle wire of the three) but the gauge gets no reading! no movement whatsoever!

19

Still no reading on my Air/Fuel gauge!! any ideas?

20

Sure you’ve got a good ground?

I installed my Boost guage today, I pulled the vacuum from that canister thing…

Hmm how to describe…

The T is right near the manifold, then the original tube runs ALL the way to the other side of the engine bay into this little container at the front of bay, someone called it a “carbon container” or something? any idea what it is/does?

Also I seem to be making 10psi and not the stock 7…