When you run your car a long while on 89 octane the trionic will set
all its parameters on using 89 octane fuel... and when it gets hot the
intercooler is less efficient... so there is a higher risk of knocking and
the ECU reduces the boost to avoid that.

Now even if you shift to 94 octane you will get no difference at all unless you reset the trionic. (This can be done by removing the battery
for a few minutes, I would however recommend that you only do that at your SAAB dealership should there be a problem afterwards)

For a primitive non turbo engine using lower grade fuel in hot weather will not make a difference, but for a turbo it will. Higher octane reduces knocking in hot weather when the intercooler does a less good job.

Let me explain this:

Intake sucks in air, turbo compresses it and heats it up by
doing so, intercooler cools it down somewhat, then next into
the cylinder where fuel gets added. If the compressed air going into the
cylinder is hoter then normal it raises the risk of knocking
during compression. Thus your turbo engine will benefit from
higher octane, if you use it all the time.

For a regular engine, hot air reduces the knocking risk as it
is less dense, thus regular engines will be able to run
fine on low octane fuel on a hot day. Cause at the start the
hot ambient air reduces knocking risks. Its less dense.

The hotter the ambient air, the more of an advantage it is to
use higher octane fuel for a turbo engine as the intercooler
loses efficiency and as the compressed air gets hoter.

The other fix is to put in a larger intercooler which will
improve the cooling of the compressed air.

So fill up 2 loads with 94, then reset trionic. It should improve!

Regards,
Coolknight

• '01 2.3lpt 9-5 5 speed sluggish in hot weather. Think octane?, John C. Womer, Wed, 25 Jul 2001 15:30:11
  • Results of 3 visits to tech, AV, Thu, 26 Jul 2001 11:28:34
  • Do the following, Coolknight, Thu, 26 Jul 2001 04:47:48 <-- Viewing This Message
    • Re: Do the following, mlc , Thu, 26 Jul 2001 22:45:11
      • Trionic, Coolknight, Fri, 27 Jul 2001 05:42:36
    • Re: Do the following, Doug, Thu, 26 Jul 2001 13:15:14
      • You wana get the Abbott or Hirsch Intercooler..., Coolknight, Fri, 27 Jul 2001 05:45:53
  • Re: '01 2.3lpt 9-5 5 speed sluggish in hot weather. Think octane?, Slug , Wed, 25 Jul 2001 23:28:49
  • Use the ACC Econ button, GaryG, Wed, 25 Jul 2001 22:47:06
  • Re: '01 2.3lpt 9-5 5 speed sluggish in hot weather. Think octane?, Gary Gordon, Wed, 25 Jul 2001 18:20:22
  • Same problem, Jeff Newton, Wed, 25 Jul 2001 15:37:57
    • Re: Same problem, Canuck Saaber, Wed, 25 Jul 2001 17:47:37
      • Re: Canuck Saaber, Michael , Fri, 27 Jul 2001 15:27:37
        • Re: Canuck Saaber --- ATT: Michael, Canuck Saaber, Mon, 30 Jul 2001 21:18:57

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