Boost spike - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

RedSuns · 08-27-2002, 02:31 AM

I have a manual controler that has served its purpose for about 2 months now...i have it set for 14psi and under WOT i go to 14psi and no more...in the past few days my boost will spike to 16psi for a split second then go back to 14psi...what culd be causing this......it has just started in the past few days...

babylon02 · 08-27-2002, 06:00 AM

I know I don't have a lot of posts, but since when does that mean you really know anything?  <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt='

'>

Double check all your vacuum lines and make sure the condition of them is all good and that none of them are kinked, especially the one your boost controller is off of.  Is your boost controller and boost guage running off of the same vacuum line?  If so, you might want to isolate them and that might fix the problem too.  I am guessing that you haven't made any other mods to your car recently.  Because that could do it too.

Hope you find the problem.

uiuc240 · 08-27-2002, 08:03 AM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (cIvIcKILLA240style @ Aug. 27 2002,03:31)</td></tr><tr><td id="QUOTE">I have a manual controler that has served its purpose for about 2 months now...i have it set for 14psi and under WOT i go to 14psi and no more...in the past few days my boost will spike to 16psi for a split second then go back to 14psi...what culd be causing this......it has just started in the past few days...</td></tr></table><span id='postcolor'>
Did the temperature recently change?  MBC's are notorious for "adjusting" boost level due to temperature fluctuations.  Maybe a cold front moved through.  Maybe it's done this randomly on other occasions, too, and you just noticed it this time.

Otherwise, yeah, check vacuum lines.

Eric

GamblerZ · 08-27-2002, 01:32 PM

Changes in intake or exhuast will affect your boost pressure.  Meanwhile, here is a good reference link:

<a href="http://www.racetep.com/turbo.html" target='_blank'>http://www.racetep.com/turbo.html</a>

RedSuns · 08-27-2002, 06:13 PM

well i did start to notice it after i put on my N1 dual.....thanks guys....

uuninja · 08-29-2002, 07:58 AM

I would say that it is your exhaust. If you were using the stock exhaust the turbo should be spinning up quite a bit faster now. MBC's are kind of like a blunt instriment, there is no way to get them perfect. If you are really concerned consider lowering the boost or gettign an electronic boost controler.

08-27-2002, 02:31 AM	#1
RedSuns Nissanaholic! Join Date: Jan 2002 Location: Northern VA Age: 43 Posts: 1,865 Trader Rating: (1) Feedback Score: 1 reviews	I have a manual controler that has served its purpose for about 2 months now...i have it set for 14psi and under WOT i go to 14psi and no more...in the past few days my boost will spike to 16psi for a split second then go back to 14psi...what culd be causing this......it has just started in the past few days... __________________ Johnathan 2005 Titan 1996 240SX 1991 240SX 1974 260Z 1996 Honda CBR 600 F3

08-27-2002, 06:00 AM	#2
babylon02 Join Date: Aug 2002 Posts: 7 Trader Rating: (0) Feedback Score: 0 reviews	I know I don't have a lot of posts, but since when does that mean you really know anything?  <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=''> Double check all your vacuum lines and make sure the condition of them is all good and that none of them are kinked, especially the one your boost controller is off of.  Is your boost controller and boost guage running off of the same vacuum line?  If so, you might want to isolate them and that might fix the problem too.  I am guessing that you haven't made any other mods to your car recently.  Because that could do it too. Hope you find the problem.

08-27-2002, 08:03 AM	#3
uiuc240 Nissanaholic! Join Date: Apr 2002 Location: Naperville, IL Age: 46 Posts: 2,093 Trader Rating: (0) Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (cIvIcKILLA240style @ Aug. 27 2002,03:31)</td></tr><tr><td id="QUOTE">I have a manual controler that has served its purpose for about 2 months now...i have it set for 14psi and under WOT i go to 14psi and no more...in the past few days my boost will spike to 16psi for a split second then go back to 14psi...what culd be causing this......it has just started in the past few days...</td></tr></table><span id='postcolor'> Did the temperature recently change?  MBC's are notorious for "adjusting" boost level due to temperature fluctuations.  Maybe a cold front moved through.  Maybe it's done this randomly on other occasions, too, and you just noticed it this time. Otherwise, yeah, check vacuum lines. Eric __________________ 2002 Mazda Protege5 1989 S13 w/SR20DET (sold)

08-27-2002, 01:32 PM	#4
GamblerZ Zilvia Junkie Join Date: Aug 2002 Location: West Texas Posts: 414 Trader Rating: (1) Feedback Score: 1 reviews	Changes in intake or exhuast will affect your boost pressure.  Meanwhile, here is a good reference link: <a href="http://www.racetep.com/turbo.html" target='_blank'>http://www.racetep.com/turbo.html</a> __________________ Visit WTI - WestTexasImports.net

08-27-2002, 06:13 PM	#5
RedSuns Nissanaholic! Join Date: Jan 2002 Location: Northern VA Age: 43 Posts: 1,865 Trader Rating: (1) Feedback Score: 1 reviews	well i did start to notice it after i put on my N1 dual.....thanks guys.... __________________ Johnathan 2005 Titan 1996 240SX 1991 240SX 1974 260Z 1996 Honda CBR 600 F3

08-29-2002, 07:58 AM	#6
uuninja Zilvia Addict Join Date: Dec 2001 Location: Reston, VA Age: 47 Posts: 812 Trader Rating: (0) Feedback Score: 0 reviews	I would say that it is your exhaust. If you were using the stock exhaust the turbo should be spinning up quite a bit faster now. MBC's are kind of like a blunt instriment, there is no way to get them perfect. If you are really concerned consider lowering the boost or gettign an electronic boost controler. __________________ Lurker Supreme! www.midatlantic240sx.com 91 Coupe 97 KA24DE+T SOLD