[Main 9000 Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos Mind the Gap Like This Post: - Subscribe to Daily Digest for this Bulletin Board Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Mon, 13 Jul 2009 10:29:15 In Reply to: Car Rocking at Altitude/Mtns- Long, Cary, Mon, 13 Jul 2009 09:33:00 Alert me when someone posts in this thread: Members do not see ads below this line. - Help Keep This Site Online - Signup

Engine miss under boost is a classic sign of too-wide spark plug gap. This can be due to an overly-large gap in the plug itself, or where the plug connects to the DI.

Pull the DI. Step 1 - look at the top of each spark plug. Do you see any burned marks on the tops? If so, that's a sign that the spring that connects the spark plug to the DI coil itself is weak.

Pull the plugs and inspect. Make sure (1) they are the proper NGKs, and (2) the gap is correct. Re-gap them to a hair under the nominal spec - plug gap increases with time. If they aren't the right NGKs, get them - No substitutions!

Step 2 - flip the DI over (coils facing up), and remove the plastic cover (about 6- 8 torx screws.) Look at the metal face of the four coils. Do you see any burn marks where the springs touch? If you saw burn marks on the top of any plug or the face of any coil, carefully stretch the corresponding spring a little so it makes better contact. While you're in there, hold the DI up to the light, and look through the coils as best you can. They should be about 90% full of liquid. If any one is low or otherwise obviously leaking, the DI has an issue.

Of course, a good tune-up is always a good idea. And invest in a nice tank of higher-octane fuel.





posted by 192.249.47...

• Car Rocking at Altitude/Mtns- Long, Cary, Mon, 13 Jul 2009 09:33:00
  • Re: Fuel pump at high altitude, BobS, Tue, 14 Jul 2009 10:14:50
  • Maybe similar symptoms, Montana Tom , Mon, 13 Jul 2009 12:24:31
  • Mind the Gap, Ari , Mon, 13 Jul 2009 10:29:15 <-- Viewing This Message
  • You need a new DI cassette, swedespeed7, Mon, 13 Jul 2009 09:42:30
    • Re: You need a new DI cassette, Simon S, Mon, 13 Jul 2009 09:52:46
      • Clean the BPC for fun..., AeroAndy, Mon, 13 Jul 2009 10:37:07
        • Thanks, All...., Cary, Tue, 14 Jul 2009 10:28:49

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