X-post: Help with Boost Spikes
 

<img src="http://d.pramanik.home.comcast.net/post/spikes2.gif">
<img src="http://d.pramanik.home.comcast.net/post/spikes3.gif"><ul><li><a href="https://forums.audiworld.com/s4/msgs/1411982.phtml">https://forums.audiworld.com/s4/msgs/1411982.phtml</a</li></ul>

definately do a leak test...

check N75 Duty cycle and Ign Timing

This little gadget....>>
 

<center><img src="http://images2.fotki.com/v20/photos/7/7305/191484/DSC00657-vi.jpg"></center><p>Which you can build for about $50 totally eliminates spiking on my car. Also provides a dial-a-boost arrangement. Smooth too...&gt;&gt; Follow the links to the Autospeed articles for more info..<ul><li><a href="http://public.fotki.com/ttschwing/boost_machine_and/">Boost Machine</a></li></ul>

The S4 engine bay doesn't have enough room for that stuff...
 

So I'm planning on going with a more compact version:
<img src="http://www.joepmbc.com/site_files/xz.jpg">

... installed in this fashion:
<img src="http://www.boostvalve.com/images/1.8T_n75_bv.jpg">

-Dave Pramanik

I tried something similar...>
 

(Dawes Device) Didn't work worth a damned. Ball and spring valves are not the ticket. If that's a bleed it might but I don't think it is. That's the JoeP, right? You can just do the regulator part of my set-up for a whopping $20.....It works.

Good luck.

Yeah, its the JoeP one...
 

A few S4 owners (as well as 1.8T owners, I think) have had some success with it.

I was hoping to install it today, but didn't get that far. I did discover (via pressure testing) that the dealership failed to install a clamp on my MAP sensor when they replaced the torn tbb. :-/ Once I got a clamp on that, I didn't find any other boost leaks. Boost is still spiking though.

Really all I need to do is open the wastegates at a perscribed level (~1.2 bar), since the N75 is failing to do that in a timely fashion. After the initial spike, the N75 is adequate in controlling boost. If the MBC works as advertised, it should do the trick. I'll definitely report back once I've got it install and test it out.

-Dave Pramanik<ul><li><a href="https://forums.audiworld.com/s4/msgs/1389851.phtml">https://forums.audiworld.com/s4/msgs/1389851.phtml</a</li></ul>