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Discussion Starter #1
I've been offered a VPC by someone who doesn't need it anymore. I am still BPU+. Does it make sense to fit the VPC already? I am going single eventually but I don't exactly when.
If I am going to fit the VPC now what kind of fuel controller should I use with it, the HKS GCC, the APEX'i Super AFC or something else?

Flavio
 

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sdf

I think that if you have 450 hp then your maf will be a restriction in airflow.
 

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I noticed quite a bit of difference in power, BOOST levels, and intake sound. Previously, I had my DSBC set to a ratio of ~54 to hit 1.22kg/cm2. After the VPC install, I had to reduce the duty cycle down to ~47 and when it's at night ~41 to keep the boost down around 1.22kg/cm2.

And, if you still have any boost leaks or problems with BOV venting, the VPC will not fix these but will not be affected by them because it's a speed/density system and is not measuring the intake air. I still recommend fixing all boost leaks, especially the pesky one that's near the EGR valve.

I too am prepping the car to go single, while getting the most from the car while it's at BPU++.

And best of all it's FREE or at least less than the price of a new one to you...so what are you waiting for.
 

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Discussion Starter #5
Spool said:
I noticed quite a bit of difference in power, BOOST levels, and intake sound. Previously, I had my DSBC set to a ratio of ~54 to hit 1.22kg/cm2. After the VPC install, I had to reduce the duty cycle down to ~47 and when it's at night ~41 to keep the boost down around 1.22kg/cm2.

And, if you still have any boost leaks or problems with BOV venting, the VPC will not fix these but will not be affected by them because it's a speed/density system and is not measuring the intake air. I still recommend fixing all boost leaks, especially the pesky one that's near the EGR valve.

I too am prepping the car to go single, while getting the most from the car while it's at BPU++.

And best of all it's FREE or at least less than the price of a new one to you...so what are you waiting for.
Can I use the VPC on its own for the time being or am I forced to install a fuel controller at the same time?

Flavio
 

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Flavio said:


Can I use the VPC on its own for the time being or am I forced to install a fuel controller at the same time?

Flavio
The VPC is stand alone, it just replaces your stock MAF, w/ the speed density system. If you want further tuning ability you can get a GCC or other Fuel Computer.

But you may not want to use it, so you can send it to me. Email me privately for my address, I'll gladly pay shipping. ;)
 

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Flavio:

As Ryan said, it's standalone. I have definitely noticed more power...with just the VPC on!!!! You will too!

I haven't installed the fuel computer yet...it's going on wednesday for tuning.


Ryan:

If Flavio doesn't send his to you, there was a post regarding used VPC recently...hope you find one, it's working very good so far ;) !
 

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Discussion Starter #8
Allright guys, you've convinced me. How easy or difficult is it to install?

Flavio

BTW It has been offered to me but not for free!
 

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Flavio said:
...but not for free!

Didn't think so...but people are beginning to get much kinder these days! Those VPC's are $$$$!

Very easy to install. I like to take my time and get it very neat, so it took me just about 3 hours total.

Go to mkiv.com and read the tech article. One thing that may help...remove the charcoal canister bolts and lay it over onto the engine bay. Then, you can get to the bolts that secure the wireing harness boot that attaches to the fire wall. Remove this boot. Then, I cut into the back of the boot and fed the VPC harness through the boot with soap/watter and then down into the ECU area. This would be *VERY* difficult if you tried to get the harness through the boot without detaching it and clearing space.

After that, just a new pressure sensor and temp probe in the manifold.

Here's a pic of the new pressure sensure attached to the fitting where the PS line attached (the blue hose goes underneath the STB and connects to the pressure sensor that's mounted to the gold bracket. All you can see is the top of the gold bracket). The PS line *T's* into a fitting on the inside of the manifold along with a few others.

Later.
 

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Maury,

I strongly recommend you redo the pressure sensor install.... It's not good to have it T'd into a source that has other components as well, ESPECIALLY the power steering hose.. the power steering vacuum affects the sensor's reading a lot and can cause serious rich/lean conditions based on steering input. AMHIK... Go try to do donuts and your car will stall as if you're out of gas (happened to me)..

Here's how I installed the pressure sensor..

On this first image, ignore the multi-T crap, I undid that.. that's how the shop originally installed my VPC last yer.. but notice the mounting of the pressure sensor..



Now.. since EGR is unnecessary.. unbolt the EGR thingee on the back of the manifold closer to the passenger. After disconnecting it, remove the hose going from the EGR VSV to the manifold.. now you have an unused nipple on the back of the manifold... use it for the pressure sensor:



Don't forget to put the inline filter 2" from the pressure sensor in the sensor hose.

Andi
 

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Andi:

Thanks.

Just want to clarify something.

I have the *new* pressure sensor *ALONE* connected to the manifold fitting where the power steering used to connect to.

I have the *old/stock* pressure sensor *T-d* together with the power steering, a hose that used to come up under the manifold, DSBC hose that goes into the cabin, and one other sensor that's mounted to the manifold (fuel pressure regulator?).

Are you recommending that I redo the *old* pressure sensor connection? Should I connect the power steering line stand alone to where the manifold where the EGR VSV was connected?

Also, is the *old/stock* still used for engine management?

I also connected my BCC into the VPC harness.

Thanks!
 

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Spool said:
Andi:

Thanks.

Just want to clarify something.

I have the *new* pressure sensor *ALONE* connected to the manifold fitting where the power steering used to connect to.

I have the *old/stock* pressure sensor *T-d* together with the power steering, a hose that used to come up under the manifold, DSBC hose that goes into the cabin, and one other sensor that's mounted to the manifold (fuel pressure regulator?).

Are you recommending that I redo the *old* pressure sensor connection? Should I connect the power steering line stand alone to where the manifold where the EGR VSV was connected?

Also, is the *old/stock* still used for engine management?

I also connected my BCC into the VPC harness.

Thanks!


I'm not sure it's a good idea to move power steering to the same line that feeds the fuel pressure regulator and the old/stock turbo pressure sensor (if that's what you're saying you did). Personally I'd put the PS line back where it used to be, by itself, and connect the new pressure sensor to the back of the manifold. Either that or leave the new pressure sensor where it is and install the power steering hose to the back of the manifold if that's easier.

Andi
 

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Andi & others:

Is there a difference in pressure from the back of the manifold from the front? Not sure if the throttle or trac butterflys closing/opening may give different pressure readings that could throw off the VPC....ie. throttle on/off or during WOT shifting with trac on with AUTO trans. Under WOT shifts with trac on, the BOV should releive pressure from the IC and the engine will suck in pressure from the butterfly back in the manifold....so maybe this is not an issue.

The VPC instructions say to attach the *new* VPC pressure sensor to the manifold fitting where the power steering is connected. So, there may be a difference in pressure.

I think it would be easier to re-attach PS to it's stock location and move the *new/VPC* pressure sensor to the rear of the manifold.

So is the power steering actually pressure releiving or does it increase the pressure reading?

Can you verify any of this?

Thanks!
 

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Spool said:
Andi & others:

Is there a difference in pressure from the back of the manifold from the front? Not sure if the throttle or trac butterflys closing/opening may give different pressure readings that could throw off the VPC....ie. throttle on/off or during WOT shifting with trac on with AUTO trans. Under WOT shifts with trac on, the BOV should releive pressure from the IC and the engine will suck in pressure from the butterfly back in the manifold....so maybe this is not an issue.

The VPC instructions say to attach the *new* VPC pressure sensor to the manifold fitting where the power steering is connected. So, there may be a difference in pressure.

I think it would be easier to re-attach PS to it's stock location and move the *new/VPC* pressure sensor to the rear of the manifold.

So is the power steering actually pressure releiving or does it increase the pressure reading?

Can you verify any of this?

Thanks!
Maury,

The top of the intake manifold is a big box and it's all basically got the same pressure, wherever the nipple is. But putting many devices on the same nipple is not recommended because there might not be enough volume of air going through one nipple to give each a good signal.. for example, back when I had that ugly "Multi-T" you see in the picture, and I had my boost gauge on it, the boost gauge would flutter at part throttle vacuum because of this.

The VPC instructions are dumb. The best and easiest way is by taking out the EGR thingee and using the now unused nipple at the back of the manifold exclusively for the VPC's pressure sensor. The VPC pressure sensor is critical, it is the most imoprtant sensor used by the VPC to monitor incoming air and decide how much fuel to put in... you don't want it to share an intake manifold nipple with anything else.

When you have stock twins.. the stock pressure sensor has a few functions.. mainly controlling 1st turbo boost and triggering the 2nd turbo transition, and engaging the 12v mode on the fuel pump when you go from vacuum to boost. Just FYI.. When people go single, some of them remove the stock pressure sensor altogether as it is unnecessary at that point. (Removing it = FFCD).

Andi
 

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Andi,

I gathered that the VPC pressure sensor should be on it's own...and hooked it up that way from the beginning. :) It's obviously *very* important to get a good reading...and even the VPC instructions imply this fact since it actually states to attach the sensor by itself to the stock power steering fitting on the maifold.

However, you've brought up the multi-t potential problem with the other connections...

I will try hooking the VPC pressure sensor to the back of the EGR fitting and put the PS back on it's original fitting.

BTW - what is the vaccum reading on your DSBC display at idle?

Thanks!
 
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