blakduc1 wrote:Quote: "it's unlikely to be the FIM / Ultimap chip where the fault lies...
the fault is there with the OEM Ducati chip, too... "
Yes... but my point was just that if the problem exists in the Ducati fuel mapping, then I would think that the FIM chip would have solved that problem by designing the best map for that engine..... that they would have been aware of this stumble and remedied it with their product.....
I'm a late-commer to the 907 fraternity. I haven't owned my 907 since new - so I don't know if the stutter / misfire was there all along. I find it difficult to believe that Ducati (or any OEM) would or could sell a bike that ran that bady... although the local Ducati agent rode the bike once and said something to me to the effect " you can't expect a Ducati to run smoothly - it's not Japanese"....maybe so but surely it was designed to run better than that.
Was the misfire there in "as new" machines - or does it develop?
If it was there from new (15 years ago) I would have thought that it would be very hard to sell the bike - a decent test ride and you'd pass it by...
If it gradually develops that would indicate tolerancing problems - as components wear a bit the various tolerances send it out-of-tune...most commonly engines can be tuned back (that's what mechanics do) so I'm kind of bewildered...
Maybe in the quest for engine response the fly wheel is engineered too light, too. I don't suggest that would cause the problem but it might compound it...
back to the chips - I'm sure that Ducati, FIM and others design them for performance - and the testing is mainly done on dyno. I expect that the tests are fairly short and not too much "on road" is done by the chippie - and that when it is on road tested the bike is cained hard - not cruised or trickling through traffic...
I am aware some chips just rich-up the map with fuel to try to eliminate rough running - maybe that's all that can be done with the dinosaur P7 injection system.
again, I don't know - but I'm sure there is a lotta science in developing the fuel map. It must be right most of the time.
If i'm going to add fuel anywhere I'd like to see some HP / torque improvement. If I had the time and money I'd probably consider fitting a Jefferies MyP8 and play with it...but I'm not willing to throw any more $$$$ at the bike unless it's a guaranteed fix silver bullet.
the misfire in mine has been observed on a computor - it took them a few days to see it because it's intermittent...the spark and fuel times go all over the place (that's not the chip doing it - it's the ECU). The only reason the ECU will screw up like this is if the ECU is rooted (highly unlikely) or the inputs are haywire.
the basic "variable" inputs are:
12 V from the battery (steady - so long as the regulator and rectifier are OK)
the TPS resistance / output voltage [two TPS units trialled]
the resistance from the WTS
the resistance from the ATS
the resistances from the MAP sensor
the timing signals from the hall effect sensors (crank and valve gear timing)
we did observe an AC spike from the regulator (on oscilloscope) which we thought might upset the ECU and we put in a new unit - the wiring was also modified a bit to ensure the power supply to the ECU was conditioned through the battery.
we put in fixed resistors to lie to the ECU so the temperatures were set at WTS 80 degrees and ATS 40 degrees...
the hall effect sensors were swapped with proven good ones
the MAP sensor still had fluctuating outputs...
the power supply to the MAP was even rigged up with batteries to produce a steady 5 volts supply...the output resistance was still fluctuating.
The MAP output was steady with engine off (as you would expect).
We swapped the MAP sensor with a proven operational one.
in this whole exercise we did not remove the vacuum from the engine (that I remember, anyway). I don't know why - but I'm sure we didnt.
about 6 months later after this testing I tried the cigarette butt.
I am yet to put it on an oscilloscope but my guess is the MAP signal will be "steady" now (within a reasonable operational tolerance).
I'd like to try to get more people to try the cigarette butt to see if damping gives similar results to what I get.
I don't know how the ECU reads the MAP signal - does it take the top value, bottom or average? Is it switched at all pressure readings (i.e.: does it always have an effect on the ECU) and how often does it sample? every second or minute or every revolution? my guess is it samples instantaneously electronically every revolution and if the signal is fluctuating due to induction pluses that the instantaneous reading may vary by 20% - depending on what time it reads the pulse.
How the ECU copes with this to deliver a smooth running engine is a bit of a mystery...but it obviously depends on how much the MAP signal coefficient modifies the algorithm