Originally Posted by The Vigg
So what values are these ECU tunners modifying then to get increase in airflow/boost, without the CEL being engaged? A combination of all values from IAT, MAF, MAP? I doubt that they are going so far as to change all the parameters you are indicating. With most ECU tunning SW you can pull the Hexidecimal values directly in to a 3d map, and simply pull the points in the rev range you want for boost, fuel and ignition maps. It's definately not rocket science, and with a wide band, and a dyno, in maybe 3 hours max you would have a 99% workable , safe map set. So the costs of these ECU's is clearly not warranted on the most part. I just have never heard of and ECU being so troublesome as this. No other car I know is this difficult to tune. I have built cars running stand alone ECU's that seem to be an easier job then this thing!
We are talking about two different things here
1.reprogramming the ECU
2.fooling the ECU
The first should not be that hard if you have the right tools. Just increase the wanted airmass/combustion to the wanted values and you are about done.
Since the system is expecting a increased airmass/C flow now why would it light the CEL?
What I wrote above is true when fooling the ECU, these things need to be looked after if you want to be sucessful in what you are doing. Search around in different saab boards and see how many piggyback systems will work with T7 that will work with many other car manufacturers. T5 can be fooled no question about it and it only has three maps to begin with. T7 on the other hand carries about 1000maps.
Why is the T7 so hard to fool? It is too smart compared to many other similar products in use by other car manufactures. For instance knock control, you wont find a similar ionization measurement in any ohter car. This feature alone will get you in trouble if you dont know what you are dealing with. T7 is constantly running on the "edge" when thinking from the view of knock. this is because the engine will perform the best when it is one the limit of knock.
I you want study around about the T7 there are many places to look.
Get WIS for starters and if that does not satisfy you, look here