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You need to remember that the Viggen is a T7 car and works on a very different principle than the older 9000's do.
Firstly the T7 system works on airmass principle, which means that it does not boost to a target pressure value, but to a target airmass.
T7 measures the airmass via MAF (actual airmass) but also with MAP and manifold temp (calculated). The MAF signal is used to calculate the needed fuel in most circumtances, but it is also adjusted by the calculated airmass.

When driving on the road (normally) the driver gives the signal to ECU via the gas pedal. This is called a request for airmass. T7 will then check all the limitations, for instance torque limit, auto tranny gearbox limit and so on to choose the maximum allowed airmass for this perticular driving situation. This value is then translated to a volt reading for the throttle plate. If the value can't be achieved with throttle control turbo control steps in and adjust boost pressure in a way that it will correlate with the requested value.

To my knowledge this is perfectly normal for steves viggen to boost less with a better IC. This is due to more dense air in the manifold. So we actually need less boost to achieve the same airmasss flow into the cylinders. As a rule of thumb you can say the following. If intake temp is lowered by 20deg C or so, you can cut boost by 0.1bar and still have the same airmass.

The T7 needs some time to adjust to the new setting, so if just change out the IC your mixtures will be off for a while. Under time the ECU will adjust and everything should be ok again.

T7 will similarly compensate for cold weather (less boost), high altitude (more boost), higher humidity (less boost). All these changes aim at keeping the target airmass.

posted by 195.237.1...

• Installed spearco IC on Viggen today, Steve88SiS, Sat, 28 Feb 2004 21:41:29
  • Total cost?, Jeff in ATL, Sun, 29 Feb 2004 08:30:35
    • Re: Total cost?, JohnInAtl, Sun, 29 Feb 2004 12:14:30
    • Re: Total cost?, Steve88SiS, Sun, 29 Feb 2004 08:48:04
      • Re: Total cost?, Dean, Sun, 29 Feb 2004 09:21:43
  • Don't understand this...., zeke, Sun, 29 Feb 2004 06:06:52
    • yep, you're right, Steve88SiS, Sun, 29 Feb 2004 08:33:53
    • Re: Don't understand this...., Vigge, Sun, 29 Feb 2004 06:56:46 <-- Viewing This Message
      • I reset ecu, results, pics, Steve88SiS, Sun, 29 Feb 2004 11:15:35
        • Re: I reset ecu, results, pics, Vigge, Sun, 29 Feb 2004 13:18:27
      • Re: Don't understand this...., Dean, Sun, 29 Feb 2004 09:30:09
      • about a/f ratio, Steve88SiS, Sun, 29 Feb 2004 08:31:38
        • Re: about a/f ratio, Vigge, Sun, 29 Feb 2004 09:12:55
          • Re: about a/f ratio, sully, Mon, 1 Mar 2004 06:04:49

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