1jz vacuum line question

[qu3tzlgum8y]

Anybody have any vacuum diagrams for the 1j?? I found some, but most of the links are broken..

I need to know what the vacuum lines on the side of the intake towards the firewall are for..

I'm pretty sure one of them goes to the heater and splits off to a turbo pressure sender?? And the other one I have no idea what it goes to..

here's a pic of what I'm talking about

 

[seoul4korea]

http://www.supraforums.com/forum/showthread.php?t=560370&highlight=1jz+vacuum

 

[qu3tzlgum8y]

Yeah I have that diagram, but the ones I'm looking for aren't on there. I need to know where the two in the back near the firewall go, the two that are side by side.

 

[qu3tzlgum8y]

I mean on the side of the intake next to the dip stick.. the two that point down

 

[seoul4korea]

Oh crap. Sorry man I just saw like half of what you wrote lol. Yeah the front (smaller) nipple goes to you heater VSV and Pressure sensor. The large one behind that goingto some hard pipes that go behind your valve covers and connects to the other side to you BOV. becareful when you put that hard pipe back on though. last time I took it off I realized that hose was too long and it pinched it into a V-shape so I wasn't venting correctly. hope that helps.

 

[qu3tzlgum8y]

Thank you very much. I'll take a look at it tomorrow..

 

[SeanMcCabe]

Oh crap. Sorry man I just saw like half of what you wrote lol. Yeah the front (smaller) nipple goes to you heater VSV and Pressure sensor. The large one behind that goingto some hard pipes that go behind your valve covers and connects to the other side to you BOV. becareful when you put that hard pipe back on though. last time I took it off I realized that hose was too long and it pinched it into a V-shape so I wasn't venting correctly. hope that helps.

To clarify, the front one goes to the heater VSV and pressure sensor? What pressure sensor?

 

[qu3tzlgum8y]

I believe it goes to the turbo pressure sensor

 

[te72]

Sean, I'd love to help ya out here man, but my setup is kinda Frankensteined, we got vacuum where we needed and where we could, so mine isn't exactly factory anymore, but it works for my particular setup. I'm pretty sure we hooked up the turbo pressure sensor to one of those nipples, even though the stock gauge in mine is covered by the Zeitronix wideband display... only reason it's even hooked up anymore (stock gauge is nigh useless anyway) is to get rid of the code that it throws if it's disconnected.

 

[seoul4korea]

To clarify, the front one goes to the heater VSV and pressure sensor? What pressure sensor?

The front one goes to a T bar. One end goes to the Heater VSV and the other end goes to the Pressure sensor (AKA Turbo pressure Sensor.) It should be located on the drivers side of the engine bay down by the clutch Res. The sensor is for the factory boost gauge I believe.

 

[SeanMcCabe]

Ya I found the sensor, just wondering two things though. Is the pressure sensor used solely for the factory boost gauge? And if it is, will I still throw a code if its plugged in but the nipple is just capped (like its reading neutral pressure 24/7)?

 

[seoul4korea]

Ya I found the sensor, just wondering two things though. Is the pressure sensor used solely for the factory boost gauge? And if it is, will I still throw a code if its plugged in but the nipple is just capped (like its reading neutral pressure 24/7)?

LOL I think it's just for the gauge. After all you have a MAP sensor that your ECU takes readings off of. The old mechanical boost sensor in these cars aren't the greatest so everuything would be sluggish if it did. Only one way to find out!

 

[SeanMcCabe]

Well I wasn't sure if it was for anything other then the factory boost gauge or not. Sorry, I'm not following, what do you mean everything would be sluggish if it did? If what did what?

 

[seoul4korea]

Well I wasn't sure if it was for anything other then the factory boost gauge or not. Sorry, I'm not following, what do you mean everything would be sluggish if it did? If what did what?

What I was meaning is if the ECU took readings from the factory boost gauge your A/F ratio and such would be sluggish because of the mechanics of it. The pressure sensor is a mechanical sensor so it's not the best. The ECU depends on inputs from many sensors inorder to run in closed loop. onces everything is warmed up and the ecu can run in closed loop is when the A/r ratio's and such get tuned by the ecu. The ecu won't go into closed loop if you 02 sensors are not warmed up for example. so it runs the motor rich to prevent unwanted conditions. same concept of limp home mode.

the pressure sensor if just for you boost gauge I believe. It's hook up to throw a code I guess just incase so you know to fix it. That way you know if your running at the correct boost and such. What I was saying is that you could just cap it off and see what it does or disconnect it to test if it will throw a code. Thats the best way to test it out I would think. It's nothing Vital if you know what I mean.

 

[SeanMcCabe]

Ah I see, yeah that's all I needed to know. I assume it will throw a code if left disconnected because that is why Brad (te72) even hooked his up. If it still throws a code with no vacuum attached, I'll just get a T and hook it up. Thanks for the help

 

[seoul4korea]

sure thing.

 

[te72]

For what it's worth, the stock boost gauge is an electronic gauge. I also have an Autometer mechanical boost gauge, it reads directly off vacuum/boost levels, and there is no delay like the stock gauge. Also explains why the stock gauge has a sensor with wiring hooked up to it.

I checked my lines when I was getting gas this morning, the nipple closer to the front of the engine (of the two in question) in my setup, goes to a tee that branches off to the stock boost gauge sensor and mechanical boost sensor. The more rearward of the two nipples in question goes up to a hard pipe that runs to the exhaust side of things. I forget what it hooks too, but the stock bov sounds right to me.

If I get a chance I'll pull the vacuum line off the stock gauge sensor and report back if it throws a code.

 

[seoul4korea]

For what it's worth, the stock boost gauge is an electronic gauge. I also have an Autometer mechanical boost gauge, it reads directly off vacuum/boost levels, and there is no delay like the stock gauge. Also explains why the stock gauge has a sensor with wiring hooked up to it.

I checked my lines when I was getting gas this morning, the nipple closer to the front of the engine (of the two in question) in my setup, goes to a tee that branches off to the stock boost gauge sensor and mechanical boost sensor. The more rearward of the two nipples in question goes up to a hard pipe that runs to the exhaust side of things. I forget what it hooks too, but the stock bov sounds right to me.

If I get a chance I'll pull the vacuum line off the stock gauge sensor and report back if it throws a code.

I answered your question already. The hose to the front that one that splits to the boost and VSV. The one your looking for is the line to the rear of the intake, it is larger in size right? It connects to the bottom of the pipe that goes behind your valve covers and connects to some hard lines and heads to the exhaste side? That one connects to OTHER hard lines on your exhaste side and THEN to your stock BOV is you still have it. But I think you said something about going single right? I'm looking to see if I have a picture that can show you.

As for the Pressure sensor some one told me along time ago that they are mechanical boost gauges. So I was going off of that. now you can have a mechanical to digital sensor as well. An example of this would be prosports boost gauge. Prosports has a mechanical sensor that converts the signal to digital. Maybe the wires are used to interperting the volt changes in the sensor and using the information? I'm in no way an expert when it comes to that pressure sensor I was merely trying to think of the workings for it. Also while you may have a Automotive mechinical boost gauge I would like to point out how old your supra is. your boost gauge was made in a different a time period then your car. If I had to guess anything it would be that it is a mech boost gauge with wires connected to the check engine light, but i'd have to look. I'm sure someone will jump on to correct me though. When I get home today from work i'll poke my head out side and see. Like I said I'm just guessing from what I know right now. Alot of times I have to actually go and look at my car to remember small details like that. Any more senior members car to inform us?

 

[qu3tzlgum8y]

I didn't get any codes when the vacuum lines were off.. I didn't have the bov or the turbo pressure sensor connected

 

[seoul4korea]

BOV connects to the Rear nipple not the front.