Running with unplugged N75

[GetAwayFromMe]

Will i run into any problems running with my N75 unplugged? Here is my issue. If i run just the N75 at WOT i will boost 30+ PSI I hooked up a manual boost controller and boost comes on really hard even at 1/4 throthle and it's anoying. btw: Im running parallel with the N75.

I would like to make a cut off swithch for the N75 and turn it off when im just crusing because with the N75 unplugged it boosts 9psi abd it's so much more smoother. I know that i will probably have a check engine light but that's not an issue since it's already on. If i want to go fast i just flip the switch and off we go.

What's your take on this? BTW im stage 3

[Boris]

Is your boost gauge reading correct? IIRC , w n75 unplugged you should be seeing 6-7 psi.

Regardless, yeah you can drive with the N75 unplugged as much as you want, I don't think it even pops up on the dash with a cel, but I can't remember.

But my opinion is, rather than make the cut off switch, just buy another N75, they are only 175 bucks I think from audi?

Or, just run your MBC standalone, and cap boost at 20 psi or whatever you want, then you're set, no overboosting.

[AudiXS4X01]

I have an extra N75 valve that I can sell u if you'd like, PM me if interested.

[GetAwayFromMe]

Is your boost gauge reading correct? IIRC , w n75 unplugged you should be seeing 6-7 psi.

Regardless, yeah you can drive with the N75 unplugged as much as you want, I don't think it even pops up on the dash with a cel, but I can't remember.

But my opinion is, rather than make the cut off switch, just buy another N75, they are only 175 bucks I think from audi?

Or, just run your MBC standalone, and cap boost at 20 psi or whatever you want, then you're set, no overboosting.

Overboosting is not an issue anymore since i hooked up a manual boost controller and it's set at 20psi. My problem is that my car is very jumpy at take off boost comes on very hard and the car will jump. II i was running with very low boost like 9psi it's som much easier to control the car it's somewhat anoying because i would like to be able to take off smooth. If i want to take off easy i have to be very light on the throthle if i were to tap the pedal it will almost jump as if the pedal was pressed in 1/2 way.

[spinny]

Did you ever fix your crazy vacume issue?

[GetAwayFromMe]

Did you ever fix your crazy vacume issue?

Yes There was an inline checkvalve that was somehow broken.

[spinny]

Yes There was an inline checkvalve that was somehow broken.

Good stuff! isn't it a great feeling when you fix something and actually have your car 'back' ??

My car was suffering some WACKY electrical issues and now it's fixed - so stoked!

[Rajan147]

I run a MBC in standalone with my stage 3.

Personally, I think you are best suited to getting a JHM in car manual boost controller setup which will allow you to crank up the boost when you want more. That way, you cap spikes and "power-up" when you need it.

I remember of some one basically using solenoids and relays to trigger valves that would allow the driver to switch between parallel and manual.

[GetAwayFromMe]

I ended up getting a different N75 valve and it still boosts 30+psi. Looks like gonna have to stick to a MBC from now on :/

[GetAwayFromMe]

Just turn the mbc a couple pounds down man.
Run the n75 as well.
And find the spot to safely run the mbc.

Your boosting 30+ because its turned too many times..

You probably misunderstood. I was running 30+ psi on N75 only. I tried a different N75 because i thought it was bad and causing my overboosting problem but it wasnt. I had to hook up a MBC to lower my boost to about 20psi

BTW: Im rinning it in parallel with the N75

[S4-ORCE]

You shouldnt be boosting 30+ stop trying to band aid the problem with a MBC and fix it right.

[GetAwayFromMe]

You shouldnt be boosting 30+ stop trying to band aid the problem with a MBC and fix it right.

Well what do you think it should be done? I need to log the car and see what requested boost it. I need to purchase a vag com still to do that.

[mitchelltj1]

Every solve your problem? It kind of sounds like mine... Check out this thread...

http://www.audizine.com/forum/showth...ighlight=boost

I'm going to try a new N75 as well...

[rouellettea4]

My car does the same thing. It's the tune, we both run the same one. I am running a MBC in parallel with n75 and its fine. The part throttle builds boost very aggressively but its easy to get used to.

[JDM EJ1 95]

torn wastegate hose

[archimense]

If you are boosting to 30 psi with the N75, then either your tune is asking for too much boost, or your N75 doesn't work. Those are the only two things that explain your problem.

Running the MBC in parallel will not allow you to boost higher than the N75 is requesting.

[csre9]

torn wastegate hose

Ding ding ding

[Boris]

could be a leaking wastegate hose, thats easy to check though, unplug the n75 and see how much boost you make, if its about 7 psi, the lines are fine...

sounds like whatever file you're running is off to me though.

[NOTORIOUS VR]

^^^ If you're not getting boost to the WG, you're going to run whatever the turbo's can give you (which is why you bleed off boost from the WG to run more boost).

to the OP, try looping the boost/vac signal directly to your wastegate lines... If you do that, they should only be boosting ~7psi. If you're still boosting a lot you have an issue with the line going to the WG or the WG themselves.

[NOTORIOUS VR]

In an Audi you send more boost to the WG to run more boost. If no boost is sent to the WG then it is only the WG spring pressure that holds the WG closed.

The S4 engine technical manual explains this.

What you're saying is just plain untrue.

Unplug the wastegate line on your S4 and tell me what happens. I'll be waiting.

[archimense]

What you're saying is just plain untrue.

Unplug the wastegate line on your S4 and tell me what happens. I'll be waiting.

Yup, I'm wrong. I must have been smoking crack. Springs hold the wastegates closed, pressure is applied to the wastegates to open them.

Not sure how I got that backwards. I'm going to check the technical guide again, because I believe it mentions they specifically designed the boost control to fail with minimum boost and not maximum boost.

[archimense]

You should log your requested boost, and your N75 duty cycle. That will give you some more info. N75 duty cyle of 100% is wastegates closed, duty cycle of 0% is wastegates open.

[GetAwayFromMe]

I used a MBC to fix this problem. When i unplugged the N75 iT DIDNT BOOST OVER 7PSI AND I ALSO CHECKED FOR LEAK IN wg LINES AND IT WAS FINE. i THINK MY OVERBOOSTING PROBLEM WAS CAUSED BECAUSE MY EXHAUST. i HAVE 3' ALL AROUND.

[csre9]

I used a MBC to fix this problem. When i unplugged the N75 iT DIDNT BOOST OVER 7PSI AND I ALSO CHECKED FOR LEAK IN wg LINES AND IT WAS FINE. i THINK MY OVERBOOSTING PROBLEM WAS CAUSED BECAUSE MY EXHAUST. i HAVE 3' ALL AROUND.

Dude that wouldn't change anything. LOL

[NOTORIOUS VR]

^^^ It is possible that the tune you're tunning isn't sensitive enough for your setup I guess and it's reacting quickly enough for the boost spike (although unlikely). But if everything is working fine with the MBC just stick with that.

The more likely scenario is that there is an issue with the N75 wiring and/or ECU output holding it all the way open (if you've checked the N75 duty cycle in VAG and that reads normal) regardless of what the ECU is asking for, or the ECU is commanding it to be open all the time for some reason (software issue).

I just find it hard to believe that two N75's are bad, and I VERY highly doubt that this is caused by a 3" exhaust.

[archimense]

You should log your N75 duty cycle and requested boost, otherwise you are really just guessing.