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ECUs cannot be upgraded as the level of integration bewtween the ECU and other things like the radio, varies from year to year. In 1996 OBD-II was introduced and pre and post would not interchange.
I think that there is also a difference between 5spd and auto box ECUs, perhaps some others can elaborate on that.
The T5 is a speed density system, that uses RPM's, absolute pressure, temperature to determine the air mass flow and maps fuel accordingly. The volumetric efficiency is accomodated within the O2 sensor adaption loop. The fuel mapping will trim to changes in humidity etc via the same method. This level of adaption accomodates variabilty in sensors and will also take changes to intake and exhaust in stride. So this is the ideal system for making mods.
The T7 has a air mass sensor to drive the mapping and the system will adapt to exhaust and intake changes as well. However, it does not control boost to a specific boost pressure, but boosts to deliver target air mass flows to try to boost to certain amounts of torque. This can be good in controling boost in lower gears to avoild completely overpowering the tire traction. But the factory targets for lower gears might be too conservative... don't know for sure. There still is a map sensor for an arbitrary pressure limit. The effective boost is also controlled by the motorized throttle. So if you install a MBC, the throttle will fight against that and limit booost. So the MBC is not effective for getting more boost. The MBC will also lead to a CEL if set to high and the ECU decides that it does not like what it is having to do. A MBC can be installed in series with the BPC to get faster turbo spool up which gets rid of the bleeder valve type boost lag that the BPC creates.
Like all mass air sensor based systems, if a boost dump valve is installed, the air dumped to the atmosphere will cause the idle to stumble as the ECU will also map fuel for the air that is vented. The mixture will be rich and the CEL will throw a CEL for O2 levels or for misfiring. So a recirc bypass valve must be used.
posted by 65.68.10...
, Sat, 14 Sep 2002 15:08:44, Sat, 14 Sep 2002 21:02:01
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