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      Old spark plugs and weak ignition coils may cause you to experience misfires as we increase the power output of your Saab. We can monitor misfire events using the data logging feature on your new handheld tuning system to quickly identify which cylinders are experiencing misfires.

      Why might your engine misfire after tuning it? —> The electrodes on your spark plugs erode over time, increasing the width of the gap that the spark must jump for each combustion event. This requires more energy to fire the spark, and an old/weak ignition coil may not have enough energy stored for appropriate ignition – resulting in misfires.

      As we raise the power output we also increase the charge density in the cylinder, which also increases the energy required to fire the spark. Resetting the gap on the spark plug withing factory tolerances (~0.95 mm) can reduce the tendency of misfires – reducing it sightly further can compensate for a marginal ignition coil, so we recommend setting the gaps to ~0.80 – 0.85 mm when changing your spark plugs. If we still observe misfires on any cylinders then we recommend replacing the ignition coil on those cylinders.

      With our VTuner handheld tuning system or the HP Tuners VCM Suite it is possible to monitor each individual cylinder for misfires to quickly identify which coils are defective and we only need to replace the individual coils that continue to show misfires after checking / adjusting the spark plug gap.

      The cylinders are numbered as folllows:

      1 3 5
      2 4 6

      The back cylinders (1,3,5) are a bit more work to get to, but the front 3 are very easy.
      If you want to order the coil and replace it yourself I have attached instructions as well as the part number and pricing.


      The coil part number is 1269037 – you can order them from numerous sites for under $50 each. Rock auto (http://www.rockauto.com) usually has them for ~$40 each and SaabParts.net has them for $30/each. I personally have been using the SMP Blue Streak coils that are listed under the heavy duty option on RockAuto.com: STANDARD MOTOR PRODUCTS UF375  Blue Streak

      • This topic was modified 8 years, 11 months ago by VTuner.
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      • This topic was modified 3 years, 1 month ago by VTuner.
      • This topic was modified 3 years, 1 month ago by VTuner.
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