No vacuum and boost creep
 

Just installed my defi blue racer gauge on my 87 t2. Install wasn't to bad. Started the car up and there was no vacuum? I went around the block and the car boosted to 6.5psi until about 4000rpm it shoots up to 10psi!?!?!? I have rb full exhaust, rb fuel cut controller, ported wastegate. The wastegate obviously can't be ported if im creeping? When I bought the car I was told it was ported. Its scares me, good thing I installed the boost gauge or I wouldn't of known.

It would be great if someone could clairfy boost creep for me. The way I think of it, a free flowing exhaust with a ported wastegate would require intake. I've been told not to do intake. But technically if more air is escaping out the exhaust, you need more air to keep up?

My idle is fairly rough. When I start it, it idles at 1.5k like normal but rises to a rest at 2k rpm. Should be down to 750. Could a vacuum leak make my gauge not read any vacuum? The idle lowers itself after some driving, I sometimes see it come down to 750.

I forgot to mention the 4000rpm rise to 10psi, has a very loud high pitch sound. In between 3800-4100rpm.

check for leaks all over the place.

Where did you install it again? You didn't put it on one of the nipples on the back of the UIM that does not receive vacuum, did you?

I thought you told me to put it on that nipple in another thread? Where should I go then, T into the already existing T coming from the pressure sensor to the intake mani?

http://i154.photobucket.com/albums/s...manifold-s.jpg

use the front nipples.......on the front of the uim. Boost creep is prolly due to a aftermarket exhaust and d/p. Better yet buy a vacuum distribution box.

Yea I have the rb d/p. What should I do about it?

it should be on the very bottom nipple if you use the back of the UIM. the rest do not receive vacuum.

Plug it in the same vaccum hose that goes from the Intake manifold to the MAP sensor. the one on the passengers side shock tower.

about the boost creep dont worry until you conect the gage on the right place you just probably have a shitty reading because of where you conected the Gauge. after you fix the gauge then go ahead and see if your boost is still creeping. good luck

If I remember correctly there was something already on the bottom nipple. I put the hose on the top nipple, because there was nothing on it. So, take the hose off of the bottom nipple and move it to the top and put the boost gauge on the bottom? Then I will read vacuum?

By the way thanks alot for following up on this gauge install arghx. The install was easy because of your information provided. The only thing I did differently from what you told me was routed the red 12v wire directly to the battery. I found the white wire on the ignition harness had power but couldn't figure out how to get the clip of wires off of the ignition cylinder. The white wire was awkward to get at. In the near future, or even if you know how to get the clip of wires off then i'll move to the white wire instead of running a huge ass wire through the engine bay.

you will read vacuum but i doubt it will change your boost reading. 10 psi sounds about right from what i can remember when i had the same setup. Make sure you have a fcd and fuel upgrades(fuel pump, etc) .

Thats the problem, I only have the rb full exhaust and fcd. Sounds like fuel is next. I was hoping I could keep the fuel stock. I prefer to stay at 6.5psi. Its weird how it boosts at 6.5psi up to 4k rpm and then jumps to 10psi though? That's boost creep correct? So should I port the wastegate more, or get intake or what?

Always keep fuel system in mind, remember you don't get a second chance when you lean out a rotary.

So with my setup, what would you recommend? Walbro pump and what for injectors?

So what is the hose on the bottom nipple? Is it necessary for that hose to receive vacuum?

Tough to say if your not 100% sure how big the wastegate is ported. 4.4k when the boost goes up could be the twin scroll working????:Wconfused

I have to mods and still run factory boost. Which is a good idea if you want your car to last. Here are some more mods I've done on my TII in addition to yours.

S5 wastegate and manifold (boost creep gone for sure!)
Replace fuel rail
Add new ground wires to engine
upgrade oil press regulator (kinda overkill)
TID mod
remove ALL emmissions
Koyo rad


Also make sure it has a full tune up and that all heatsheilds are in place.

Cool thanks. I want to keep factory boost, and in the future upgrade fuel so I can up boost to 10psi. So for the s5 wastegate and manifold was it all direct bolt on and all accessorys attach the same as s4? Did you port the s5 wastegate?

I used your method, and you get brownie points. I now read vacuum. When the car feels like being nice at 750rpm im getting 10-12 vacuum. When the idle is being a deusch as usual i'll get 20 vacuum.

I actually used my s4 turbo and only used the hotside of the s5 turbo and s5 manifold. I also ported the s5 wastegate as well. Try and find a blown s5 turbo and use half of your s4 turbo. The s5 turbo manifold is a much better design. IT is a direct bolt on. I run 5.5lbs in all gears with the above mentioned mods and I have no boost creep!

By manifold are you talking exhaust or intake? So, if I bought a blown s5 turbo wouldn't there be a chance the hot side is blown?

I nearly forgot, do I need just the upper mani or the lower as well?

So I now have the boost line T'd into the pressure sensor. There it doesn't seem to show boost creep. Steady 5.5psi and onwards. Which spot is more true, the pressure sensor or the top nipple on the UIM that showed 6.5psi up to 4k rpm then jumped to 10psi??? I hope the pressure sensor is a true boost reading because that means I dont have boost creep. :)Since my idle is fucked vacuum is at 20.

why would mazda put the pressure sensor in that nipple? Im guessing it is the most accurate one thats why. thats the one Ive always used and never had a problem with it.

Thanks bud. The nipple your talking about isn't one of the 3 on the uim is it? Your talking about the nipple that the pressure sensor sits on?

yup, the one for the pressure sensor.