I don't want to get into a long protracted discussion on this except if someone has some insight on technical discussion about the ecu control, but I tested some 9mm 850ccm nozzles, but I had issues with being able to control fuel injected after drivers wish is removed, ie the engine rpm stayed above 4000 rpm for up to a couple of seconds after a power run with no throttle. The rpm then droped. I did also have a bit of run on where I believed I may have blown the engine and turned the engine of with the key and the rpm took a couple of seconds before it dropped, but the engine was fine. Understandably I only tested this once by accident.
This was beyond my knowledge of how to fix, so I returned the nozzles to the manufacturer who is currently doing some further tests.
As I understand a modification has been made to the injectors such that the key off run on no longer occurrs. There still remains the issue of the run on under ecu control which the manufacturer is working with his tuner and has made some progress.
Whilst testing the nozzles I did not manage to get an imporvement in power using the same comparitive boost as with standard nozzles, BUT, I am not sure if this was being impacted by what was causing the key off run on issue which may now be resolved, or beacuse we need significantly different soi timing than with the standard duration/SOI combinations used. I have a hunch that the timing wants retarding.
The short comparitive tests I ran showed the extra fuel being injected as between 35% and 50% extra. I am not sure how that relates to Bosio R783 in extra fuel flow.
I plan to get another set back, but i am testing something else at the moment which has an impact on my decision of which version would be best, but hopefully that will be finalised in a week or so.
The technical bit:
I don't have as much understanding as some others on all the ecu maps. The big bore nozzles will inject more during the pre-injection stroke. What is not clear to me is how the duration maps on the ecu relate to the solenoid activation to commence the whole injection cycle as there are negative duration values for small quantities particularly at high rpm. My understanding of this is that the duration maps therefore exclude the extra bit added on to start the whole injection cycle. There is also a map which controls how fast the injection quantities are allowed to change, which have some peculiar values at high rpm, it may be they are designed like that to prevent the rpm form dropping too quickly during gearshifts etc.
I don't think it takes much fuel to keep the motor spinning at 4000rpm if there is no load, and it could be the pre-injection quantity is of this order and the maps need adjusting to deal with it.
Regards
