Oil Pressure and Boost Gauges not working after 1jz

[ocerrahyan]

Hi guys,
I searched the forums but it appears my queries are too short to provide any reasonable results. After i bought my supra years ago and performed the 1jz swap in my 1992 chassis, the oil pressure and boost gauge (factory setup) never worked. I never had this problem or care when i had my NA-T SC because well, there was no factory boost gauge or oil pressure gauge to worry about. Easy fix- aftermarket gauges.

Now though, i am cleaning up the Supra and want to focus primarily on the interior. Starting with the non-working boost and oil pressure gauges. Of course, back then with the 7m, they worked but after the swap, no luck. Sensors are in place and everything is hooked up, but i have decided to do another checkup this weekend in the garage. Could you guys please fill me in on where to start? I am very technical, and have always done all my electrical and engine work as so with the Lexus and the GN so im not afraid of tackling this.

Please help and happy thanksgiving.

thank you in advance.

 

[hvyman]

Need to use the 7m oil pressure sensor.

And need the boost gauge sensor hooked up with vacuum and the connector.

 

[ocerrahyan]

Need to use the 7m oil pressure sensor.

And need the boost gauge sensor hooked up with vacuum and the connector.

Thx for the tips heavy.. So correct me if im wrong but this would explain that:
- The factory oil pressure gauge is not routed to the ECU at all and is directly wired to the back of the dash? I hooked up the sensor wire to the 1jz sensor and so im guessing that was incorrect? (Sorry guys i did the swap a long time ago before these resources were out there lol)

- The factory boost gauge uses a vacuum feed? I was under the impression the factory boost signal was generated by the MAF? At least i thought. Please correct me.

Thanks again hvyman

 

[destrux]

If you hooked the 1JZ sensor to the wire it will actually make the gauge work backwards. The gauge will read below zero if you have oil pressure, and zero if you have none. This is how mine has been working since I did my swap. It's not linear though, cause the 1JZ sensor is actually a switch that switches when the oil pressure hits the minumum allowed pressure. On the JDM cars there was only an oil light apparently, no gauge.

If you want to hook it up right you need an adapter hose to hook the 7M oil pressure sensor to the 1JZ block, because it won't fit because of the bracing on the block.

The factory boost gauge gets it's signal from a little black sensor under the hood near the top of the shock tower on the drivers side (it shares a bracket with the 7M fuel injector resistor if I remember correctly) that says "turbo pressure sensor" on it. That needs to be plugged in and hooked up to the intake manifold with a vacuum hose to work. It doesn't wire up to the engine harness at all, it's plug is attached to the body harness that comes into the engine bay near the clutch master cylinder.

 

[87supraguy]

is it a stock mk3 boost guage? why would you need it if you have a 1jz? stoock boost on the 1jz is 12psi i believe and the stock mk3 guage goes to 8psi. for this reason i put a stock voltage guage in it's place. the guage is pointless. as far as the oil guage the guys are right 7m sensor may need the DM line if you have A/C on the 1jz. just my $.02

 

[kneedragger85]

stoock boost on the 1jz is 12psi i believe

Stock is 10psi.

 

[87supraguy]

could've sworn i read some where it was like 12 - 12.5 psi. either way 10 psi is more than 8psi and therefore makes the guage useless.

 

[MKIIISupraGuy]

Have you looked at the TSRM

Sent from my DROID X2 using Tapatalk

 

[te72]

...and boost gauge (factory setup) never worked...

You said it right there. Once you get it hooked up right, put an aftermarket one next to it, and compare response times. Hell, mine would already be nearly peaked out at 10-12psi before the stock gauge was even registering boost. It's a novelty at best, to be honest.

But, if you want it to work, it needs to be hooked up to a vacuum line (I believe it connected to the intake manifold), and wired in.

 

[hvyman]

At least you can see your boosting over 8.