Monday, 22 September 2014

Back at it again

So after a few months of not being able to work on the bike at all I am back at it again.

I haven't done any more physical work on the bike since, just tuning and refining the control side of the injection.

Below is a quick video of one of some of the first rides running with injection.

I was relatively sure I had populated the fuel table to be safely rich to begin with but I did a slow run up through the revs at first, attempting to hold relatively steady throttle and revs at various points in order to build up a log of the fueling. After that, I stopped and checked the log for any lean areas or overly rich areas. and adjusted the fueling in that part of the table to compensate. There were a few areas that needed attention. The rev range log and adjust was repeated a good few times that aren't shown in the video until I was absolutely sure I wasn't getting any lean areas.

I then attempted a few runs that contained a mix of coasting, gradual and hard acceleration to see how the engine reacted under normal riding conditions. It doesn't like very quick throttle openings but that is to be expected as I have acceleration enrichment disabled for the initial tuning process. Acceleration enrichment adds additional fuel during acceleration depending on the rate of throttle opening. The lack of this is most evident while trying to blip the downshifts.

Circa 6-7,000rpm at small throttle openings sounds quite rough (0:30-0:45 in the video). It has improved since that clip in the video but hasn't disappeared so that will need further work.

Also the Koso dash does not seem to like the high revs and drops signal anywhere between 10-14,000rpm as you can see in the video. It looks like it misinterprets and loses sync with the signal coming from the ECU and then catches it again. The point which the loss happens seems to vary as well as the time before it picks up again. I have had no chance to investigate this yet but first on the cards is to fit an inline resistor as this cleared up my VR signal issues going to the ECU last year. I have also discovered a setting in Tunerstudio that allows TACHOUT to output half speed signals. There is a chance the Koso will like these slower signals better and it can then do its own internal multiplying to get back to the correct RPM reading.

Over the last few days I have been logging full cold starts (engine stopped for more than 12 hours) and summarising various initial conditions such as cranking PW, idle VE, coolant temp and time to engine start. I am defining engine start as the point at which engine speed rises above 1,000 RPM. The summary results will hopefully build up a good database on which to base changes to the cranking PW curve to get the quickest possible starts. So far I have not had any real cold starts. The last 3 starts ranged from 15degC up to 22degC. Each achieved engine start within 0.95-1.52 seconds. Starts were achieved with zero throttle and no choke.

I have noticed also that my logs are recording INJ2 timing of 0deg constant during engine running although the semi sequential injection should make it 180deg offset from INJ1 timing. The INJ1 timing shows correctly as per table so it may either be a glitch in the software or elsewhere to say that INJ2 appears not to be timed. If this is the case it may explain the slightly rougher than expected running.

More to come as refinement progresses.

1 comment:

  1. I don't suppose some shielding is out of the question? I'd wager the dash is dropping the ECU signal because it's too noisy for it to handle at high RPM. Years ago another group from Australia fuel injected a Suzuki GR650 ( and they also had trouble with electrical interference; their solution was a diode bridge, which I'm sure would also work. I'm sure shielded cable isn't too hard to come by though, and it would give you a very clean signal without having to condition it too much (see page 8,

    Keep up the good work - your project is progressing amazingly well! It's great to see it coming together!