Good questions. Let me digress for a moment. The way that i realized that the Oilhead would run much better with a few percent more fuel was when I noticed how much better my bike ran while a little cold and just before the bike had warmed-up. It ran much stronger while there was some post-start or warm-up enrichment of the mixture.vwdoctor wrote:Has anybody (looking in your direction Roger) attempted to play with the oil temperature sensor readings. If you fool the ME into thinking that the engine is cold (or colder) it should provide additional enrichment as well. I understand that I will probably not go into closed loop but the effect should be permanent. I don't think they were too concerned with "engine not reaching operating temperature" as they are now. I might experiment a little. It would be the equivalent of booster plug except if engine never goes into closed loop it should never adapt itself out. Amount of additional fuel could be controlled with the value of the resistance.
It would be "oil temperature shifting"
The simple answer is that I have measured the oil temperature versus enrichment curve for the Motronic. It adds 3-15% enrichment post-start based on temperature and is coupled with a post-start time factor as well.
At first this seems like a good possibility, but there are some gotchas.
1) Even if you try to fool the Motronic into thinking it hasn't warmed up, you still want the temperature display in the RID to read correctly. This means cutting the common wire that goes to both the Motronic and the RID.
2) you can't hold the Oil Temp sensor at a constant value since you want good starting at very cold temperatures. So the function needed is allow the signal going to the Motronic to be real while very cold but stop warming up, And the RID must always read true.
3) To accomplish 1) and 2) above you need to cut into the oil temp sensor wire and insert a circuit that drives the oil temp with a limited signal but the rid with an unlimited one. This means splitting the common wire, I have a design for this circuit in my desk but never built it.
4) The Motronic monitors all sensors for plausibility. Although I haven't confirmed it, it is likely that the oil temp sensor, if limited, would throw a fault.
5) Since the harness would have to be cut, it cannot be plug 'n play.
6) If one overcame all the above problems, you still would lose closed loop operation.
Considering 1-6, I decided to go the lambda-shift route. Although it's difficult to understand lambda-shifting and its implications, once that work is done during the product design phase it is simple for the rider to implement. All you do is unplug the oxygen sensor and plug the lambda shifter in series with it.
RB