Author Topic: Turbo vacuum routing - is this right?  (Read 1428 times)

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Offline fidelity101

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Turbo vacuum routing - is this right?
« on: June 27, 2017, 07:53:28 AM »
I believe that I have a JDM UIM but this is how I have the setup currently, is this correct?



Its an S4 car with S4 electronics (my 10AE) rats nest/emissions removed (still running BAC) running a S5 turbo & S5 intake/exhaust manifolds. Do I still need that switching solenoid? is that only applicable to the s4?

I feel like I am missing something...

Offline toplessFC3Sman

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Re: Turbo vacuum routing - is this right?
« Reply #1 on: June 27, 2017, 08:46:33 AM »
The throttle body and spacer between it and the manifold are also S5?

I ended up ignoring most of the online vacuum layouts since there were at least 3 different types of manifold and throttle body, and the connections in some cases depended on which combo you used. What is important is whether the vacuum source is taken from before the throttle plates, right at them, or after them. Before the throttle plates will see boost but not vacuum (which I think the OMP and injector air bleeds require IIRC), the BOV should be after the throttle plate so it will see vacuum when the throttle closes, as should the brake booster. I need to look up the routing that I settled on for the connections for the PCV system, as that one took a few iterations to get right and I don't remember the specifics right now.

Offline fidelity101

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Re: Turbo vacuum routing - is this right?
« Reply #2 on: June 27, 2017, 12:43:23 PM »
yes they are. I have made my own weatherpack connector for the TPS so I can use the narrowband for the S4 ECU.

after some researching I am missing the wastegate or boost control system.

the omp/airbleeds I got right and I'm not using the OMP because I premix on this engine.
the brake booster I have a port on the LIM that goes to the rear runner but that is hooked up to a tube along the firewall to the checkvalve before the booster.

I don't have a PCV system on the car, the evap canister is plumbed directly to the port on the bottom of the oil filler neck.

Its an s5 turbo, s5 turbo manifold and s5 turbo intake manifold, s5 turbo throttle body spacer and throttle body but using s4 electronics with the rats nest and ACV removed.

then with that the BOV i have hooked up is correct or do I need to T this into the MAP line?

I'm just confused on the boost solenoid then for the wastegate.
« Last Edit: June 27, 2017, 12:47:53 PM by fidelity101 »

Offline toplessFC3Sman

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Re: Turbo vacuum routing - is this right?
« Reply #3 on: June 27, 2017, 01:11:50 PM »
All the wastegate needs to see is a MAP signal with boost, so it doesn't really matter which one it looks at. If you use a nipple right at the compressor housing, this will provide good responsiveness for boost control, and will be slightly more conservative since the pressure will be highest before flow losses and density changes going through the intercooler.

BOV should be on a nipple that is connected to the intake after the throttle plates, so that it sees vacuum and boost. Whether the nipple shown is connected there or not, I don't really know. I'd avoid T'ing too many things off of individual nipples, since each of these things is a small leak and can throw off the signal for other things on the same nipple. This is especially true for the MAP sensor - it should have it's own dedicated nipple that sees boost and vacuum. I don't know which is usually used for this on the S5's.

Offline fidelity101

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Re: Turbo vacuum routing - is this right?
« Reply #4 on: June 27, 2017, 01:43:17 PM »
So I hook up the line from the nipple on the outlet on the compressor directly to the wastegate and then done?

What about the boost control?

I don't have any T's in my system right now and I don't plan to add any. I think my prior vac leak/poor idle was because I had the nipple on the compressor hooked up to the switching solenoid then the outlet of that to the check valve directly to the port behind the throttle plates...

IE:

Do I just put a plug on this port circled in yellow and call it a day? (s5 turbo on s4 engine)



because this line goes right from the wastegate to the compressor housing. Do I need to mess with the switching actuator anymore for the s4 twin scroll? I know the s5 has electronic boost control solenoid so I'm at a loss on how to plumb this.
« Last Edit: June 27, 2017, 04:16:10 PM by fidelity101 »

Offline murz

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Re: Turbo vacuum routing - is this right?
« Reply #5 on: June 28, 2017, 06:10:09 AM »
I believe I have a tee or two even, I'll have to go back over my system, would explain the issues I'm having too. On my car I blocked off that nipple.
1986 AS GXL Turbo swapped
1993 VR R1

Offline toplessFC3Sman

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Re: Turbo vacuum routing - is this right?
« Reply #6 on: June 28, 2017, 08:35:35 AM »
Ah, I forgot that the S5's have a boost control solenoid from the factory. If you're using an S4 ECU, then you won't have the control output needed for this and should just cap the extra nipple (yellow circle). For an S5 ECU, this should be hooked up to a solenoid valve that is controlled by the ECU to dump some of the boost "signal" to the wastegate, allowing the turbo to build more boost at lower engine speeds (basically PWM to reduce the pressure trying to open the wastegate).

With the routing you were talking about before, it would definitely cause idle issues since air could essentially bypass the throttle plates by going through the solenoid valve, causing a leak of metered air (so no lean condition, just a high, possibly hunting idle)

Is the boost control solenoid the switching solenoid that you're talking about (in your third paragraph)?

You can ignore the twin-scroll actuator - either wire it open or cut off the arm and plug the hole in the manifold completely.

Offline fidelity101

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Re: Turbo vacuum routing - is this right?
« Reply #7 on: June 28, 2017, 08:55:14 AM »
yup.

makes sense, why I couldn't find a vacuum leak it was an internal self induced one.

my extra long S5 UIM intake bolt comes in the mail today, the interfooler is on so i can adjust idle while running and then this should be good to go!

I don't have the twin scroll actuator itself because I'm using the s5 turbo manifold.

Offline fidelity101

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Re: Turbo vacuum routing - is this right?
« Reply #8 on: June 28, 2017, 06:52:20 PM »
hooked up everything, adjusted the throttle body and TPS works great!

I am using the S5 throttle body as well on my car with the s5 TPS. I just cut the wires and used a weatherpack connector it is more robust and has better connectivity to it than the beat up old connector. I also made a connector for the wide range so if I decide to go haltech or something it is ready to go. Right now the car is using the narrowband like the ECU likes, it does in fact run on the wide range but it gets a bit weird under load...