Cold start information

[74Nitro]

I start every season with a new and fully charged battery. I will pull my battery at the end of the season and install it in one of my other sleds with a battery much older. I have not been having any issues with cold starts. Canada last year -20f for three days in a row and no issues.
Any time some one in the group I happen to be with has an issue with any sled, Viper, Apex, or Nytro the first thing someone does is get out the jumper cables and most of the time the sleds fire up.
Our problems are not confined to one symptom or explained with the routine by which the problem is solved at the moment. What works for one may or may not work for another. One issue may have been solved but the underlying problem has not been fixed however the clue is in the solution.
I know if my crank speed is too low my sled will not start. I will stop cranking and get it jumped. Is it the battery or the inability to vaporize properly at low temps or crank speeds, or something else.

"It started, thank god"

I had an 08 Nytro for many years and I was amazed how it would still fire up on a very weak battery. I'd be cranking it thinking to myself there is no way it's going to fire, and then all of a sudden it is running.
I do agree however that trying to start a machine that is not cranking over fast enough is not usually a good idea. Boosting it is the right thing to do like you suggested.

 

[jjmoneysauce]

This is a huge sore spot with me and irritates me to noEven though that shouldn't have to happen.

Have you installed the updated 8MS relays?

 

[stomper]

I never installed them. It’s a 2017 btx that I bought brand new last January from the dealer so if there were new updates I doubt it has them. Maybe I’ll contact them to see if there are any available.

 

[jjmoneysauce]

Oh yeah definitely give them a shot. They're like 20 bucks each. Came out in November 2019. I think there is a new ECU flash available as well that you might not have.

 

[2015ViperMTX]

Or get them from mouser for a few bucks a piece

 

[stomper]

Well I had the opportunity today to try a cold start on my BTX. Air intake sensor was reading -30C(-22F), volts were reading 11.4V. I hooked up the booster pack, cycled the fuel pump once and it started on the second try, and a lot easier than I was expecting. Once it started I held the key on for about 5 seconds just to make sure it didn’t stall. If I hadn’t held it on I think it would have stalled. I will say that even with it being a bit of a pain having to hook up the booster pack I am super happy that I can get it going in -30C weather

 

[Vmax]

Or get them from mouser for a few bucks a piece

Yep, I ordered them for like 5 bucks each

 

[stomper]

Did another cold start test today. Intake temperature was -16F (-27C) hooked up the booster pack and it started quite easily first try. It was -33C earlier this morning but I just crawled out of bed and just couldn’t bring myself to go out and try. Clearly the cold start issue a battery voltage problem. At least It’s looking that way with my sled. No way would it have started before either temperatures.
Now I’m kicking myself for not trying it at -33C this morning

 

[TD Max]

So it was -21°f this morning local temp. Weatherbug said -19°f. Viper outside and not started for 3 days now. Decided I wanted to do a test start just because I'm goofy that way. Rolled the key immediately to crank and started spinning. Definitely labored and did not inpsire confidence, but I stuck with it and eventually it started to pup a little then started clean. one crank of probably 10 seconds. The Doo was inside the trailer. It too started about the same. Maybe a bit less crank, but started fine. Doo battery was new last season. Viper is the original. I do have an EVO 2.5 flash on my ECM. Not sure but I think it is 2015 based. Previously I did have a no crank incident last season but was able to swap relays to get it to crank. I now have the sealed relays in place for the fuel pump and ISC.

Both machines run Mobil Delvac 1 5w40 oil. Viper has about 2k on the clock and Doo low teens. Both 91 non ethanol. Viper is mostly fresh this year, Doo is leftovers full tank storage from last season.

 

[stomper]

Well that’s good news.

 

[stomper]

Did another cold start text today. Intake air temp was -27F (-33C). Volts 11.4. Coolant temp -27F. Hooked up the booster pack and it started first try. Only cranked over for about 5-10 seconds and fired right up.

 

[Vmax]

Good to hear, glad I invested in a booster pack

 

[stomper]

Another thing that I also do is hold the key on for a few seconds to make sure it stays running because if it stall it doesn’t start quite as easy. It does this enemy if it’s warm.