300ZX (Z32) Performance / Technical Discussions related to Turbo charging, Supercharging, Engine, ECU, exhaust, and etc. performance enhancements and Techical related.

Spark plug and boost leak questions

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Old Oct 30, 2007 | 01:06 PM
  #1  
w8lifter21's Avatar
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From: Illinois
Spark plug and boost leak questions

PFR6B-11B
or
PFR7B-11B

and where's the best place to get them? These are the correct length for a twin turbo right?

My mods are:
JWT pop
test pipes
HKS cat back
ECU
larget SMICs by years end, maybe even injectors

The car has a little bit of a rough idle, and slight "miss" through the RPM range. I assume this could be because of tired plugs and or the boots that cover them.

Could a boost/vaccume leak cause the rough idle AND sputter through the RPM range? The car still pulls hard. Breaks the tires loose at full boost in 2nd gear. When I did a pressure test at the rubber T by the MAF, I hear a hiss coming right under/around the "twin turbo" sticker on the manifold. I used a rubber safe HVAC spray that bubbles with an air leak, but I didn't see any. I hooked up the compressor, gave the boost tester a few squirts of air, I could hear the hiss at less than 1psi of pressure, and it would stay hissing for a good 10-15sec. I am using the PVC cap with tire valve stem that's in the FAQ/DIY. Suggestions about the plugs and where the leak could be from?
Old Oct 30, 2007 | 05:43 PM
  #2  
b300z's Avatar
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Joined: Jun 2004
Posts: 2,518
From: Lafayette, IN
youd probably be safe with the 6B-11Cs, but the 7B-11Cs would not hurt. especially if your running higher boost.

do you have a boost/vac gauge? if so, is your vacuum low at idle?
what is this PVC DIY youre talking about? woody's PVC relocate?
Old Oct 30, 2007 | 07:44 PM
  #3  
w8lifter21's Avatar
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From: Illinois
the DIY is a boost leak tester. Home depo 3" pvc pipe plug, the kind with a square in the middle of the round cap. drill a hole in the middle of the square and throw on a rubber tire valve stem. shave down the threads around the cap and stick it in the rubber T where the MAF usually goes. Now you can use the same hose you use to fill your tires to build pressure. word on the street is you don't want to go much more than 3psi of pressure. I had my compressor regulated at 1.5-2psi
Old Oct 30, 2007 | 07:47 PM
  #4  
snwbrderphat540's Avatar
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Joined: Sep 2005
Posts: 9,532
From: lemont, Illinois
i would go with the slightly colder ones, it will help if u do raise the boost, and honestly, your best bet is to order them from a Z store like ultimate Z. local stores will charge you about double the price. i know i found that when i was searching NGK plugs for my Z32
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