When you first reset the ECU the IAM is set to 8 (unless it's been remapped and the Initial IAM is set higher).
This gives you half the advance timing map.
The ECU has a base timing map and an advance timing map.
The base timing map is the least amount of timing the car will run for example at full boost 4500rpm timing may be 20 Degrees.
On top of this is the advance timing map which will give ou for example an additional 8 degree's.
With an IAM of 8, you will only get 4 of the possible 8 degree's therefore giving you 24 Degree's of timing.
you still with me.........
With an IAM of 16, you will get 8 of the possible 8 degree's therefore giving you the maximum possible 28 Degree's of timing.
With an IAM of 2 you will get only 2 degree's so 22 in total. 'BUT' with the IAM this low the ECU will also limit the boost to about half and put it into a kinda limp/safe mode.
The learning procedure above is kinda OK but the 2001> ECU tend to learn fairly quickly and a couple of spirited full throttle 3rd gear pulls and a couple of 1/2 throttle pulls will increase the IAM from 8.
But if the IAM was higher then 8 before the reset all you will do is retard the timing then advance it back to where it was.
Also, if for whatever reason i.e poor fuel, a problem or anything that can cause a slight bit of det, the ECU will just pull the timing again.
Unless you have put the wrong fuel in, the ECU will sort itself out.
i.e it can pull timing, but can also put it back in again.
This is what makes the difference when you put V-power or Tesco 99 RON in the car.
If the IAM has reduced to say 12 on 97RON, you are not running the maximum available mapped timing.
If you then put V-power or 99RON in the timing may advance back to an IAM of 16, therefore giving you a tad more power.
However if the IAM is already 16, then adding V-power/99RON will not cause any timing adjustment and therefore you may not feel any difference.
|