Possible kickback solution?

[Janne339]

Mike P
I check some of my old files in the mcx-logger and you have a good point! Battery voltage drops when I turn the key and turn the starter on! This time down to only 9,3 Volt.

Red is battery voltage and white is RPM. But I gonna log some new files and see if it happens every time?

 

[Janne339]

And AFR (green) went crazy when engine fire up???

 

[Mike P]

Decomp
Valve clearance
Wiring
Battery
Weak gear and starter
Fuel tune
Ignition tune
Prime start method
No prime start method
Hold key after running
Let go of key early
Throttlebody sync
Map sensor hose routing
Different throttlebodies
Different Ecu

All these and more I am sure are rarely or never discussed in Nytro forum and anyone of them can help or hurt the issue. It's not simple for sure.

The battery on a Nytro is very close to the starter. The cables between the battery and starter are more than likely the same size or larger AWG. The cables on a viper under most conditions are obviously fine to turn the engine over.
Voltage drop across a conductor is very easy to see with the proper meter and also easy to fix in theory.
The ability to diagnose the direct cause or causes of voltage lost in a circuit is not as easy as one might think. Voltage and current are dependent on each other in an electrical circuit and one is dependent on the other to be present in a circuit.
If a device requires a certain voltage to operate properly the wattage or power is predictable with respect to the load connected. If the voltage is changed the device (starter,Ecu,ect) will still try to function properly however if the voltage is to hi or to low the result will not be acceptable.
All electric devices have what is known as a threshold voltage. When the threshold voltage, hi or low is reached the reliability of the device or devices will be compromised. The threshold voltage of the ECU will be very different than a starter and that threshold voltage will be very different than the solenoid. The working voltage (required voltage) of each component should be the same although the low voltage threshold condition will different for each.
As the current rises in a circuit, for example the starter engagement the voltage common to each component will be under increased demand. In a Direct Current circuit the power demand will affect the Voltage available unless the supply is sufficient to overcome the demand. The same applies to Alternating Current circuits however the affects would not be as noticeable and would have a larger range in the threshold between hi/low.

The battery might just be in the wrong spot, to far from the load and the cables are to small to compensate for the length.
Just my $.02

 

[grizztracks]

I don't believe it's a voltage drop issue that's related to the battery being located in the rear. I installed an engine, wire harness and ECU from a Nytro in the viper chassis with the battery still located in the rear and it fires up flawlessly like the Nytro's always have. My belief is that the Arctic Cat ECU is flawed and it may be beyond a simple flash to correct it. I recently replaced my ECU on a 2014 Harley Street Glide with an aftermarket ECU. The Harley ECU is not flawed but there is only so much you can do with flashing it. We know what works but I'd be surprised if Yamaha ever goes back and properly corrects the sleds already out there.

 

[grizztracks]

The Voltage drops due to the battery location in comparison to the Nytro can easily be calculated. Although I don't believe that to be the issue, I guess the Cat ECU may be more sensitive to the slight voltage drop. If the voltage drops below a given threshold the ECU may not have the capability to properly process signals. Again, that would be an ECU issue that probably can't be corrected by a flash.

 

[4StrokeAddict]

Been following this for a while now considering I'm on my third starter. I believe the problem to be a compound problem. Though voltage drop is possible, 9 volts should be within tolerance especially since these levels can be seen on cold days from chemistry voltage drop. One of my more severe kickbacks happened just after I unplugged it from the battery tender on a fairly warm day...

I have always believed it is a 2+ fold problem since not all vipers have this problem with the same flash. If it was the ECU/Flash alone, than all vipers should have issues. The more likely cause is a combination of air/fuel mixture via mechanical settings coupled with the ECU/Flash. The ECU could have a flaw or it could simply be the mechanical settings are outside the flash's threshold to correct. No matter what it is, I don't think it is a simple or singular problem.

 

[tnc110]

I would say this has been proposed before, but why can't they copy the nytro run file to the Viper ecu?

 

[RTX]

I don't believe it's a voltage drop issue that's related to the battery being located in the rear. I installed an engine, wire harness and ECU from a Nytro in the viper chassis with the battery still located in the rear and it fires up flawlessly like the Nytro's always have. My belief is that the Arctic Cat ECU is flawed and it may be beyond a simple flash to correct it. I recently replaced my ECU on a 2014 Harley Street Glide with an aftermarket ECU. The Harley ECU is not flawed but there is only so much you can do with flashing it. We know what works but I'd be surprised if Yamaha ever goes back and properly corrects the sleds already out there.

I would agree with this 100%
I believe the battery cables, location, and condition of the battery to be a contributing factor to this kickback issue. but I do not believe they are the solution.
Evo reflashes have shown to improve the cold starting and starter failure issues.. to my knowledge there have been no reported starter/gear failures with the evo reflashes.
Yamaha/ cat have issued a specific reflash to address this kickback issue.
the new sidewinder comes with a Mitsubishi ecu.
these 3 factors lead me to believe that the error is with the cat ecu programming, and other things help contribute to causing kickback . just my opinion

 

[NOS-PRO]

Kick-back..........engine cranks about 2 revolutions, then it just stops turning the engine over with a thud or pop, (imagine throwing an adjustable wrench in the engine where it gets pinned between the crank and rods while cranking) then continues to turn over until the engine starts or the engine doesn't start and the code comes up.

 

[tnc110]

Kick-back..........engine cranks about 2 revolutions, then it just stops turning the engine over with a thud or pop, (imagine throwing an adjustable wrench in the engine where it gets pinned between the crank and rods while cranking) then continues to turn over until the engine starts or the engine doesn't start and the code comes up.

Ok. Thanks for clearing it up. That sounds like that might be a combination of too much fuel...so much that it is hydro-locking, and/or poor timing???

 

[Srxspec]

If the battery voltage drops below 10 volts on this Yamacat system it shuts off the fuel injection & does some goofy thing to the ignition timing. Not saying it's the kick back issue, but it surely doesn't help it.

 

[NOS-PRO]

Ok. Thanks for clearing it up. That sounds like that might be a combination of too much fuel...so much that it is hydro-locking, and/or poor timing???

Actually from my sled which is a 2014 that I had the previous flash (2015). I had to add fuel in the low rpms (starting and idling) of my fuel controller to get it to start decent and idle smoother. But this was my sled

 

[Mike P]

I would say this has been proposed before, but why can't they copy the nytro run file to the Viper ecu?

I'm not sure that would ultimately fix the "kickback" issue. If the ECU file or map were to blame then my Viper would run as bad as the next guy. It does not. A battery coming off of a charger is not relevant to the Kickback issue in the fact that the voltage to the ECU was not known at the time on the Kickback.
The ECU controls fuel management, firing order and a host of other items. If the ECU failed to execute at the right time I think most people could agree that it would cause a miss fire of some type. There could be in that situation some additional reason the voltage is compromised. One very notable problem is that when the engine is cranking, warm or cold the voltage will drop dramatically. 9.5v DC is very low for a device that is designed to run on 12v DC.
In fact the voltage reading of 9.5 may not actually be the low point in the reading. Many times a meter will read a voltage and be unable to display it before it is rebounding. The voltage could be much lower for a split second. Long enough to cause equipment to fail much like the ECU. Most cars will not turn over and start at 11v DC. At 10v DC you might hear a click. I'm not sure at what voltage the ECU will shut down on a snowmobile or worse stay on but becomes undependable.

 

[cannondale27]

Low voltage also will effect fuel pressure. Rule in auto world is 11v under load minimum. Mine is real close. But it's more than one thing that can cause it. Don't chance any if possible.

 

[cannondale27]

Valve clearance / decomp clearance and throttlebody sync are the variables I believe are the clincher. Only because very few check either.