In Reply to: Sounds like engine knock!, Larry West [Profile/Gallery] , Fri, 14 Aug 2009 06:34:24

...and I have heard actual engine knock wherein APC quickly retards boost and it goes away. The only conditions where I've seen actual knock and APC subsequently pull back the boost is when it has been very hot and the mini-intercooler is sufficiently heat soaked, and it goes for a quick dip just into the red.

Knock sensor passes screwdriver test as well. I actually swapped the APC solenoid and vacuum advance capsule from my '88 which runs great but has a horrible body... that car ran and boosted like a champion with no issues before I started pulling parts for the '85. The injectors and ECU came from the '88 as well, figured those should probably go together...

This is a higher pitched clattering noise than what I recognize as knock... reminds me of when my E34 M5 had an issue with oil draining out of the filter and taking some time after firing to build pressure in the top end. That car had solid lifters, but I'd hear this terrible clatter if I applied any throttle within the first 30-45 seconds of running... perhaps I'm experiencing oil starvation in the top end but only under load, as the engine sounds great at idle and under low load conditions. I never see the oil pressure light except when in the "on" position before starting, in which case it goes away a reasonable amount of time after running (will count when I go cold start it in 10 minutes).

140,000 miles, btw.

Thanks...
--jeff



posted by 70.79.19...

• Rattle under engine load - T16, Jeff Cullen, Thu, 13 Aug 2009 18:59:12
  • throttle switch?, Hans, Sat, 15 Aug 2009 21:45:32
    • Great ideas, will check when exh. man. stud fixed! thnx, Jeff Cullen, Sun, 16 Aug 2009 15:15:21
  • Re: Knock sensor faulty??, Saabnutt, Fri, 14 Aug 2009 12:28:40
  • Sounds like engine knock!, Larry West , Fri, 14 Aug 2009 06:34:24
    • 94 octane as mentioned..., Jeff Cullen, Fri, 14 Aug 2009 10:46:35 <-- Viewing This Message
      • Ok...., Larry West , Fri, 14 Aug 2009 13:15:49
        • Thanks, Jeff Cullen, Fri, 14 Aug 2009 15:42:45
      • Plus..., Jeff Cullen, Fri, 14 Aug 2009 10:52:57
    • Re: Larry I Plugged in the UNIVAC, Frank Myers, Fri, 14 Aug 2009 06:40:12
  • Re: Rattle under engine load - T16, Frank Myers, Thu, 13 Aug 2009 19:03:16
    • Re: Rattle under engine load - T16, Frank Myers, Thu, 13 Aug 2009 19:04:37
      • I second the timing..., Saab Junkie, Thu, 13 Aug 2009 19:08:10
        • 94 octane, knock sensor OK, vac adv cap OK. hoses OK., Jeff Cullen, Thu, 13 Aug 2009 19:11:31
          • Happens under load with APC disco'd at base boost..., Jeff Cullen, Thu, 13 Aug 2009 19:15:19

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