No Boost

oh and i forgot to ask, are you throwing codes? it seems you should be throwing codes if
1. you are losing power
2. you are losing air (rich codes)

if you are NOT throwing codes, i would have to assume that the problem is a mechanical one with the throttle cable or body, and the car thinks its working fine, it just isnt getting all the input data you are trying to send it. if thats the case, its probably a very easy fix and you are pulling your SC kit apart for nothing! i think most install problems would give you codes back

those codes will be super useful in diagnosing this over the internet good luck again

I think this is looking for a zebra in a herd of horses. Go get the damn intercooler leak tested!

Originally Posted by docwyte

I think this is looking for a zebra in a herd of horses. Go get the damn intercooler leak tested!

You aren't understanding what hes saying.

He wanted to test for boost before the bypass valve, and before the manifold, so he connected the pvc pipe with a point drilled and tapped for his boost gauge to connect to.

With the pipe in place but the boost gauge installed the same as with the intercooler in place, the gauge registered zero boost.

The problem appears to be between the intake ports and the intercooler, likely the throttle body, incorrect plumbing on the bypass valve (if there is any plumbing on it), or a leaky manifold (not real likely).

I thought when he put that pipe in place of the intercooler, he showed 8psi of boost. To me, that means the intercooler is leaking.

Originally Posted by docwyte

I thought when he put that pipe in place of the intercooler, he showed 8psi of boost. To me, that means the intercooler is leaking.

No I did not remove the intercooler because I thought it was leaking. I removed it to tape my boost gauge into that area.

Ok, I connected the DME to a GT1 to check the throttle body percentage of opening. I got 83% and it does not respond as soon as I press on the gas pedal. I went to adjust the cable and I got 82% which was really weird because I practically turn it all the way down. I am not sure what the threshold should be, but logically shouldn't I get 100% at WOT?

Before I supercharged the car I had a problem where the car felt sluggish I had to press the gas closer to the floor just to start building speed like the throttle wasn't responding, The after changing electrical parts here and there, and resetting the adaptation, I would get the power back and didn't have to push the gas pedal down so far to get good power.


I think my Throttle Body is suspect here. I just ordered one from Ebay for $50 +10 shipping. I will swap it out out and see what happens.

Ok. Try and follow me here. With the intercooler in place, you have no boost. You remove the intercooler and replace it with a straight pipe and you have boost.

The throttle bodies don't not show 100%. It goes against logic, but there it is. It was the same thing with the Audi's.

Go get the intercooler pressure tested!!!! You're totally chasing your tail here and not following logic.

you are not hooking up the boost gauge to the right place. hook it up somewhere PAST the TB......

SC should show you FULL boost immediatly after PROPER install. there is NO break in period.

Originally Posted by docwyte

Ok. Try and follow me here. With the intercooler in place, you have no boost. You remove the intercooler and replace it with a straight pipe and you have boost.

The throttle bodies don't not show 100%. It goes against logic, but there it is. It was the same thing with the Audi's.

Go get the intercooler pressure tested!!!! You're totally chasing your tail here and not following logic.

With all due respect, please read what he is saying very carefully.

With the boost gauge location unchanged, with the pipe in, no boost, with the intercooler in, no boost.

Changing the location that he connected the gauge to, aka relocating it from being tapped into the intake manifold to being tapped into where the intercooler is, he got a boost reading.

Because the result with the pipe in place of the intercooler was identical given the same tap location (as he has said a couple times now, and I posted before), he doesn't need to pressure test the intercooler. He didn't want to drill a hole in the intercooler to make the test, so he used pvc.

I hope that makes sense.

Originally Posted by SC98MaximaSE

you are not hooking up the boost gauge to the right place. hook it up somewhere PAST the TB......

SC should show you FULL boost immediatly after PROPER install. there is NO break in period.

If the car doesn't see full throttle (for tuning reasons) and the throttle body isn't allowed to open all the way because of that, then he isn't going to get boost because the bypass valve will vent it.

I don't know that you're on the right track, but based on what you have posted it makes a lot of sense to me, good luck, I think it very well could be something with the TB blocking flow and thus stopping boost from making it to the manifold and letting it get bled back at the bypass.

You're assuming he had the boost gauge hooked up properly to the intake manifold.

I think this throttle body idea is a hare brained idea. Even at part throttle he should be registering boost. I've *never* heard of a throttle body going bad.

It's something mechanical, related to the plumbing or the way he has something hooked up.

Originally Posted by BimmerDude18

If the car doesn't see full throttle (for tuning reasons) and the throttle body isn't allowed to open all the way because of that, then he isn't going to get boost because the bypass valve will vent it.

i didnt read the entire thread but why wouldnt the TB fully open? if thats the case, he cant get the speeds up all that high anyway and regardless of the TB, he should be able to register a few lbs on the gauge.

also just a LEAK alone wouldnt hold you back from seeing boost, all the boost has to be lost inorder for it to stay at 0. even at idle, the SC blows a great amount of air, let alone at higher RPM's. If there is this amount of "leakage" it can EASILY be felt in the bay... trace it with a paper...

BimmerDude18, I see you understand where I am coming from. Superchargers are pretty simple it's all air being pushed into an intake manifold and extra pressure is being released through the bypass valve almost like a wastegate on a turbo chargered car so you don't over boost.

If there was a leak in plumbing, I would feel the air coming out, like I did when the TB coupler wasn't on correctly, I could feel the boost escaping from under the TB. I corrected this.

I need to know if I should be recieving 100% AT WOT rather than 83%.

When driving the car I can feel power the charger is boosting, but the intake manifold just won't read that boost Probably because the throttle won't open up and the pressure is going back to the Bypass valve and letting it out via the Air filter. Well $50 for a Throttle Body isn't bad, so I will be replacing it as soon as it gets here. Thank goodness BMWs are easy to work on.

Originally Posted by BimmerDude18

With all due respect, please read what he is saying very carefully.

If the car doesn't see full throttle (for tuning reasons) and the throttle body isn't allowed to open all the way because of that, then he isn't going to get boost because the bypass valve will vent it.

I don't know that you're on the right track, but based on what you have posted it makes a lot of sense to me, good luck, I think it very well could be something with the TB blocking flow and thus stopping boost from making it to the manifold and letting it get bled back at the bypass.

Originally Posted by lrogers80

When driving the car I can feel power the charger is boosting, but the intake manifold just won't read that boost Probably because the throttle won't open up and the pressure is going back to the Bypass valve and letting it out via the Air filter. Well $50 for a Throttle Body isn't bad, so I will be replacing it as soon as it gets here. Thank goodness BMWs are easy to work on.

Metered air does not go back to atmosphere

There was a technical paper explaining how sprint booster works and one of the chapters was regarding throttle opening at WOT. It was not 100% as many would assume but around 80%. Search here for "sprint booster white paper" and you will see what I mean.

You won't feel air coming out of a leak.

Last time, as I'm done with this thread. GET THE INTERCOOLER PRESSURE TESTED!

Docwyte,

I removed the intercooler and installed a new PVC pipe with no holes in it. Took the car on the highway and still no boost. I can see that gauge is getting close to the 1psi, but not quite. Same thing happens with the intercooler in place. The intercooler is fine. Sorry for being so confusing.

Originally Posted by docwyte

You won't feel air coming out of a leak.

Last time, as I'm done with this thread. GET THE INTERCOOLER PRESSURE TESTED!

what does the butt dyno tell you? do you feel a pull ?

my money is still on a defective gauge or bad connection. route a dedicated vacuum line past the TB for the guage.

as for receiving 100% or 83% at WOT, that depends on many things. most importantly your belt must be properly tensioned otherwise its going to slip, second, you must have a big enough filter to allow the SC to suck in enough air for you to register full boost. im sure the filter provided is capable of enough flow. what kind of fuel delivery is in place ? also i hope you know that if you granny drive it to redline in any single gear, you WONT see boost. you must go WOT.....


can you elaborate on the said TB not opening properly ? if its NOT opening fully, you will hear a lot of compressor surge, do you hear any ? thats the easiest way to get to the bottom of this TB problem.

I have not Dyno'd the car yet. I figured I would see the boost. I have the boost gauge connected to the rear of the intake manifold. There are two ports back there I tried both, also I had it connected to the bypass valve vacuum source which originally came from the purge valve vacuum port.

The car feels strong. Even in lower gears if I step on the gas, I can see the boost gauge going up just pass the 0 to almost touch 1, but no more.

I changed just about everything that could have caused the car to loose power before except for the throttle body. If it works great if not, then I am only out $50 and will have peace of mind on that note.

If not, then off to a tuner shop. Battle Ground or Balance Performance. I'll let them take this on.

Everytime I start the car from overnight I get a Peake code 08: Air Mass Sensor and F5 & F6 Secondary Air Pump... CEL stays on until I clear it. It doesn't come back on until I leave the car park over night and start it when it's cold. Still drives fine and Idles fine.

Originally Posted by lrogers80

Everytime I start the car from overnight I get a Peake code 08: Air Mass Sensor and F5 & F6 Secondary Air Pump... CEL stays on until I clear it. It doesn't come back on until I leave the car park over night and start it when it's cold. Still drives fine and Idles fine.

Ok I found out why I was getting the F5 and F6 code. When I found that vacuum leak in the rear of the intake manifold that open port in the rear that was open, belonged to the vacuum source to the secondary pump. Some how it must have blown off. I Just put it back. and Tapped into the one available port in the rear of the manifold for the boost gauge. Now maybe code 8 air meter is realated to this disconnected vacuum line. I will see in the morning. Be back soon.

Thanks again everyone for keeping me going.

Originally Posted by redronin

if you have vac at idle and no boost at WOT you (partially) blew the main boost line off the bottom of the charger (if its centrifugal)

i gaurantee it.

if the compressor was bad you would hear it.

lol redronins words are ringing in my ear..good luck..

I guess the best way to figure this out is on a Dyno. If that hose blew out then I would feel the air when the car goes into boost.

I'll let you know as soon as I get it done.