Possible kickback solution?

[cannondale27]

11,9 and 12,1 volts when turn the key. Red=voltage. White=RPM
View attachment 123840
View attachment 123844

Without extra battery to ECU. This time it drops to only 8,4 volts.
View attachment 123845

Looks pretty clear to me that this is one big part of the problem! Well done!

 

[grizztracks]

Just a thought but after studying the wiring schematic for the Viper and comparing it to the Nytro's there is a difference in how the two handle power distribution. The Viper powers the ECU, coils, injectors, oxygen sensor and ISC motor all through a single relay (ISC relay). The Nytro powers all these direct without the use of a relay. The ISC relay powers all these systems through it's contacts from the same power feed that powers it's own control coil so if the voltage drop on this power feed is significant enough it might be dropping below the voltage required to hold the relay contacts closed. This could cause the contacts to chatter and may provide an erratic power feed to the critical components. I'm wondering if eliminating that relay and powering the ISC circuit off the key switch like the Nytro does might correct some of these problems.

If anyone wants to research or try understanding this more here is a simplified schematic of the ISC relay power distribution:
(I'll also post this schematic in the FAQ section for reference)

 

[Janne339]

Great!

 

[Janne339]

How is the quality of that Cat ISC relay? Another options? It seems important that it works 100%?

 

[grizztracks]

I'm not positive but I'm assuming they're all mechanical relays which doesn't give me a lot of confidence.

 

[Mike P]

Just a thought but after studying the wiring schematic for the Viper and comparing it to the Nytro's there is a difference in how the two handle power distribution. The Viper powers the ECU, coils, injectors, oxygen sensor and ISC motor all through a single relay (ISC relay). The Nytro powers all these direct without the use of a relay. The ISC relay powers all these systems through it's contacts from the same power feed that powers it's own control coil so if the voltage drop on this power feed is significant enough it might be dropping below the voltage required to hold the relay contacts closed. This could cause the contacts to chatter and may provide an erratic power feed to the critical components. I'm wondering if eliminating that relay and powering the ISC circuit off the key switch like the Nytro does might correct some of these problems.

If anyone wants to research or try understanding this more here is a simplified schematic of the ISC relay power distribution:
(I'll also post this schematic in the FAQ section for reference)

View attachment 124424

Do you have the Nytro drawings? Do you have a part number for the ISC relay? The manufacture should have the minimum/maximum working voltage listed in there specs. I would agree that chatter is definitely possible or could cut out completely while cranking at low voltages.

 

[Janne339]

Pic of relays

 

[Janne339]

ISC relay

 

[Janne339]

https://files.acrobat.com/a/preview/8cdb3db5-4ef8-4ea7-a409-0c3acc7f093c

 

[cannondale27]

Awesome job guys glad you haven't given up! This spec underlined is what bothers me. Still electricity goes path of least resistance and draw. How do we ensure power to ecu when we are competing with the draw of starter? Will a separate circuit be enough?Yamaha obviously was way more concerned about this then others since they even regulated Handwarmers to ensure that I believe.

 

[johan]

I gonna install a secondary battery with a relay that disconnect the orginal battery when I start the sled with a relay that gonna trigger from the start relay. gonna post pics and so when I install it. after that the ecu stay at 12v no power loss.

 

[cannondale27]

I gonna install a secondary battery with a relay that disconnect the orginal battery when I start the sled with a relay that gonna trigger from the start relay. gonna post pics and so when I install it. after that the ecu stay at 12v no power loss.

That will work just be sure to use Solid State relay and ensure that it is not powered up with key off. All solid state relays do have a draw when off unless in series with a actual switch like key. We ran into that with a relay in Cannondales. Was mechanical and failed fairly often so found direct replacement Solid State worked great but it drew enough power that ECU never went into Hibernate mode so dead batteries were result. Just concerned over another circuit that adds more complication and potential for failure to a already complicated system but if it can be made robust enough. Why not? Great job. Keep track of sources,cost etc. Anything is better than the flash it seems!

 

[johan]

The relay doesn't take any power at all it will be trigged when I have the key in start position only. gonna setup some fuses between the battery's as well

 

[Janne339]

What Bosch relay instead of the Cat ISC relay?

http://rb-aa.bosch.com/boaarocs/ind...C30EA1C1F8F28AC970741ED7F.sundoro2?ccat_id=22

 

[grizztracks]

Nytro Schematic.