Quote Originally Posted by Stefan
Thanks for your reply, Mark. Very interesting stuff about the different maps stored in the chip. It brings up a few new questions:

1. Both the instrument cluster and the coding plug has been changed by a former owner. Any way to make sure the new coding plug is selecting the right map, or will any error reveal itself by a poorly running engine?
I think you would need a dealer tp read the coding plug and check what map it is selecting.

2. What happens if the map the coding plug selects is not available?
There is always a map available, as it is selecting between 3 or 4 maps that are in every chip of that vintage. All that would happen is that lets say the plug is selecting map 2 and the tuner adjusted map 3, there will be no difference in performance detected.

3. If tuning chips are made with only a single map, then how (and where?) can I get a matching chip? Has one even been made for my specific engine type? Most sellers only look at the DME number and doesn't care about the chip itself.
I'd be willing to send you a chip to evaluate, and if it does not make a difference I'll adjust another map.

4. I wonder why my fuel tank filler opening is the small one, used for unleaded gas, if my car is supposed to run on leaded? Or is it just older cars using the same DME, like the 635i, that requires leaded?

Stefan
Possibly your car is made to run on unleaded but I am not familiar with any map for unleaded and no cat. I can send you a chip to try now or I can adjust the other maps and then send a chip but it would take some time before I can do that.

Mark