Spark Plugs - pre ignition issue

[rocco16v at netzero.net (L F)]

You may be experiencing detonation rather than preignition.  The fact that dialing your ignition advance back helps would make me think detonation is the problem (and it usually is).  You can:
leave the ignition back at 4-6deg BTDC
lower your compression ratio
use higher octane fuel
utilize water injection
don't go above 1/2 throttle
keep the revs above 6000 at all times

Some of these are more acceptable than others...

Changing the heat range on the plugs will not help detonation (it MAY help with preignition, depending on what is causing the )

Larry
  ----- Original Message ----- 
  From: Benjamin Harder 
  To: scirocco-l@scirocco.org 
  Sent: Wednesday, July 23, 2003 8:36 PM
  Subject: Spark Plugs - pre ignition issue


  I've been having an issue lately with pre-ignition (pinging) on my mk1's
  2.0 16v engine.  Engine is freshly rebuilt with approximately 11:1 compression,
  running CIS-E, stock ignition, always on 93 octane, etc.

  If I set the ignition timing to stock settings (6-8 degrees) the engine
  will ping (my knock sensor is obviously not functioning).  I will then retard
  the timing to around 4-6 degrees and everything seems fine... just the fact
  that I'm losing some performance.  :(

  So, I checked my spark plugs to see that I was running the stock 3 electrode
  Bosch plugs for the 2.0 16v, which have a heat rating of 6.
  Due to my higher compression, I sourced a different Bosch plug with heat rating
  of 5 (colder plug).  Thinking that this would dissipate heat faster
  and help solve my pre ignition issue... nope.
  The new plugs don't seem to have helped.

  Anyone have experience in the high-compression world with this pinging
  issue.  Sure I could run octance booster or race gas, but I know that
  there must be a way to run 93 pump gas... right?  :/

  If I go to a colder plug (like a 4 rating), would this possibly help?

  TIA!


  =====
  Benjamin Harder
  86 Scirocco 16v
  80 Scirocco 16v
  93 Passat GLX

  http://www.geocities.com/vwtype53/

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