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Discussion Starter #1 (Edited)
TLDR

Cold start issue resolved -
  • Cold start issue started immediately after loading the Custom map, and would not happen on the Original map- never had a problem until the map was loaded
  • On the Custom map, the bike would not fire even after holding the ignition down continuously and I could smell fuel from the exhaust, indicating the fuel injection system was working properly
  • The problem was caused by a corrupted map file - the map itself was good but the file generated by Rexxer (dealer side) was corrupted
  • Rexxer US was responsive through the two week ordeal and we resolved the issue together, having to regenerate the map three times
  • The bike feels incredible w/ the tune, improving throttle response, and giving a meatier mid range from 4-6k - on the stock map, this is a very "dead" zone
Check Engine Light resolved -
  • Disabling the O2 sensors is a common request in custom maps - I had requested this in my Rexxer tune, but the CEL continued to throw after clearing
  • In the Rexxer instructions, they say to disconnect the O2s because if you leave them connected, the ECU sees them and will continue to use them
  • This is not the case with the 2019+ Desert Sleds where the ECU and map is totally different than the base Scrambler family
  • You have to keep the O2s connected, otherwise the ECU detects a drop in resistance in the circuit and will continue to throw a CEL (codes P0130 and P0150); the O2s are disabled in the map itself
  • Thank you to Liam Venter at Fast Bike Gear in NZ (NZ's Rexxer Rep) for this information and @NevM for the intro!
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Hello!

I'm relatively new here, mostly a lurker, but having some issues and could use some guidance/help. I've searched for answers/guidance over the past couple days but have not been able to find conclusive info.

Bike details
  • 2019 Desert Sled
  • Comp Werkes Exhaust
  • MWR PowerUp Kit
  • O2s Disconnected
  • EVAP Canister Removed
  • Rexxer EVO User ECU Map
I've had the Comp Werkes exhaust on the bike for over 8 months or so, no problems. But, I also wanted to install the MWR PowerUp kit with Rexxer map to tune the ECU.

I installed the MWR PUK last weekend, a couple days before the Rexxer arrived and took the bike for a spin - definitely seemed to be running hotter, but did not have any cold start issues. After the MWR install, my throttle cable was slightly misaligned and there was 0 slack in the throttle and roughly a 2mm gap at the throttle body - meaning it was slightly open.

As soon as the Rexxer arrived I sent off the ECU data for tuning and received a map. I uploaded the map reset the TPS, DTC, and Adaptive settings and started the bike / took it for a spin. It had a little bit of a hesitation to start, but I was not starting from a cold engine. Also, the CEL came back on for O2 sensors. I reset the codes and TPS again, took it for a spin, and the CEL did not come back - seemed successful. That being said, this was all on a "hot" engine. I ended up fixing the cable slack issue yesterday and reset the TPS, and last night I took it for a spin - everything seemed fine.

However, from a cold start I seem to be having issues - this morning after sitting for over 12 hours, I tried cranking the engine multiple times and could even smell raw fuel coming out of the exhaust. I even tried turning the ignition on/off multiple times in case the fuel system was not pressurizing. With no luck firing up, I reset the ECU back to the stock map, it fired right up - I let it run for a couple minutes to warm up. I flashed the ECU again w/ the tuned map, and the bike started - I assume because the engine was now hot.

I've been in touch with David from Rexxer, from whom I purchased the unit, but it's unclear what the issue could be. He mentioned the tune does not touch the bottom end/startup process and that after the flash the ECU needs to learn how to fire up, and that I should let it continuously crank until it fires. I'll give it another try in the morning, but certainly do not want to burn out my starter.

Something seems off. So, I'm also going to chase down the fuel and tank vacuum lines again, but I'm stumped because the bike seems to fire w/ the stock map and not the tuned map. Unfortunately, there's no way to diagnose the issue through the Rexxer unit as it doesn't let you capture OBD data.

The only other thing I can think of, is that when I initially flashed the ECU, the TB/throttle cable was not completely at 0, and maybe it learned w/ bad data. So I'm hoping since I reflashed the ECU to/from stock today, that tomorrow morning it will fire up after learning from a new baseline. Fingers crossed.

Has anyone faced this type of problem, any other thoughts?
 

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Discussion Starter #2 (Edited)
Quick update from this morning [here's a video of the Cold Start] -
  • Bike has been sitting for over 16 hours
  • Battery voltage read at 13.18 w/ ignition off
  • Turned ignition on and cranked the engine continuously, repeated many times
  • Could smell a ton of raw fuel and saw a few flames coming from the exhaust
  • Battery drained to about 12.86
  • After about 5 minutes, it finally fired up, sluggishly, but seemed to be running smooth
  • I think this would be considered the first "cold start" since reflashing the ECU to/from stock yesterday
  • I'll have to let it sit again overnight tonight and test in the morning - will provide an update
 

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After it finally started with the new map, did you take it for a ride and load the engine a little through out a moderate rev range? Just a normal every day ride...then shut it off. Maybe that would help, not sure but it couldn't hurt to take it for a ride after it finally kicks over with the new map.
 

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Discussion Starter #4 (Edited)
After it finally started with the new map, did you take it for a ride and load the engine a little through out a moderate rev range? Just a normal every day ride...then shut it off. Maybe that would help, not sure but it couldn't hurt to take it for a ride after it finally kicks over with the new map.
True. Today after it fired up, I let it idle for about 10 minutes, shut it down, and then about 30 minutes later took it out for a spin. The CEL kicked in for the OBD circuit (P0130 and P0150), but I suspect that's because it's still in learning mode. I've reset the CEL. Will try to fire up again in the morning and take it for a spin.
 

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Discussion Starter #5 (Edited)
Cold start issues continue, even worse this morning. Bike sat for 18 or so hours overnight before attempting this AM.

Took over 20 minutes to start the bike this morning. I even held down the starter for 2 minutes continuously cranking on the first attempt to fire up. No dice. Keyed the ignition on/off a few times and tried multiple continuous cranks and it finally fired after trying for 20 minutes. There was even a loud pop and flame at one point from the exhaust.

It also did some weird RPM hunting after firing. I shut it down after a couple minutes since the hunting seems wierd.

Inspected under the fuel tank, fuel and vacuum lines look ok, and don’t see any kinks. Fired back up a few minutes later, it started again w on issues. Took it for a 100 Mille + ride and after 30 minutes the CEL came on. I suspect O2 sensor/circuit codes - I’m still out on the road, will check again when I get home.

All in all this is frustrating and very concerning. I can’t imagine this is normal or expected as part of this tuning process, esp since it’s a typical setup and I’ve only come across a couple threads w ppl having issues w their tune.
 

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Discussion Starter #6 (Edited)
Just got home and confirmed CEL codes are yet again for P0130 and P0150, the OBD circuit. I stopped for about 30-45 minutes to have lunch and posted the message above. After lunch, I got back on the bike and took off, it cut out a couple times like it was suffocating (and the CEL light on was still on).
 

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Discussion Starter #7 (Edited)
I reset the DTC codes again last night and the bike sat for over 12 hours.

Tried to fire it up this morning @8 am - no luck. Held the starter for 20 attempts and tried a 2nd time for another 12-15 cranks.

Going to pull the fuel tank tonight. But I doubt it's the fuel lines, as I have 0 issues once the bike is fired up, including WOT acceleration.

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Update @12pm today -
  • cranked 5-10 times, it tried to start, but didn't fire
  • turned ignition on/off, cranked another 5-10 times, twice and it eventually fired
  • started to get on the throttle to immediately take it out on ride, and it died
  • cranked again 3-5 times and it fired
  • took it out for a ride 10 mile ride and CEL came on again
 

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Discussion Starter #8 (Edited)
Took the tank completely off today and found a kink in the right side fuel line. I'm hoping this was the root-cause of my cold start issues. The fuel line feels like cheap plastic - not sure why Ducati used this instead of a nice rubber/braided fuel line :|

That being said, the CEL for P0130 and P0150 continue to come back on after resetting the DTC. I've even tried setting the map back/forth to stock and custom, with a ride in between. With the stock map loaded, I plugged in the O2s and did not get the CEL. Loaded the custom map, unplugged the O2s, reset DTC/TPS/Adaptive and CEL comes back consistently.
 

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Discussion Starter #9 (Edited)
8:30am
Cranked again this morning and no fire. This is unbelievable.

At this point I can only assume that the device/map/modifications are bad.

10am
Since I reset the CEL last night, I thought I would try and reset the TPS/Adaptive for this next attempt. I did so, and it fired on first crank, albeit it struggled a little bit. But it did fire. It's almost as if the data/map/learnings are getting lost?? Something doesn't make sense.

After it fired up, I let it warm up for a few minutes and then took it for a run. After a few WOT runs, the CEL came back on.
 

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Discussion Starter #11 (Edited)
I really feel for you, must be super frustrating.

Cool that you keep updating this though, may be useful for someone else one day
Thanks for the support man. It's a very frustrating situation.

I'm going to continue debugging by reverting the ECU back to the stock map, plug the O2s back in, and monitor cold starts for the next couple days.

From what I can tell, the problem seems to be ignition timing on the bottom end of the map, maybe not enough fuel being delivered, or something defective w/ the Rexxer. It's unfortunate there's no way to view the data off the ECU from this device.

And yeah, documenting here to help anyone else that might face similar issues, and also so I can have a log to look back on of the actions I'm taking.
 

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Discussion Starter #12 (Edited)
Redline says the problem is my battery and that the Scrambler (my Desert Sled) should always be on a battery tender and that's why it's not firing. Quite literally, in the year and 6k miles that I've owned this bike, I have NEVER had any hesitation in starting the bike, even when starting from cold. It fired w/o issue up until the very day I loaded the Rexxer tune/map.

That being said, I'm in a shared garage in my apartment complex and do not have the luxury of a power outlet. I have pulled the battery and put it on my tender in my apartment (12v, 2amp, STD) for a trickle charge. It's starting from 95% right now. I'll test this w/ the custom Rexxer map/tune in the morning

Will continue to update.

Anyone out there reading this also have a Rexxer tune and leave their bike w/o a tender? Have you faced these issues?
 

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Discussion Starter #14 (Edited)
This might be a stupid suggestion but have you tried plugging the O2 sensors in with the Rexxer map loaded?
Not a stupid question at all. Thanks for ideas.

There's a couple things - I haven't tried to plug-in the O2s w/ the Rexxer for a cold start, and I assume the CEL would go away and stay off w/ them connected. The "testing" problem for the cold start, is that I basically have to wait 24 hours to try new variables :|

This was on my list but lower priority since the O2s shouldn't prevent a cold start. Also, the CEL doesn't come on until I have multiple WOT runs.
 

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Discussion Starter #16 (Edited)
Something is definitely broken w/ the rexxer custom map/data -
  • I pulled the battery and put it on a tender overnight, fully charged at 100% and is a healthy battery according to my tender
  • Attempted to start w/ the custom map, held the ignition for 10 cranks, did not fire
  • Immediately loaded the original map, no other changes, the bike fired on the 2nd crank with no hesitation
 

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Discussion Starter #18 (Edited)
Call rexxer... it’s the map if it fires up normally with the stock map.
Yep, agree thanks man - i've been keeping Rexxer US / David up to date every step of the way and have been asking for them to review the data/map.

I reached out to Rexxer EU as well but have not heard back from EU yet.
 

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I've been very happy with the Rexxer map with MWR PowerUp Kit and Scorpion exhaust on a 2015 Scrambler for almost two years. Map was installed by the local Rexxer agent (Liam - Fast Bike Gear) who posted about challenges with a DS update just a few days ago

I'm sure Liam would be happy to discuss the issues they resolved - can be contacted through FastBikeGear.co.nz

Good luck!
 

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Discussion Starter #20
I've been very happy with the Rexxer map with MWR PowerUp Kit and Scorpion exhaust on a 2015 Scrambler for almost two years. Map was installed by the local Rexxer agent (Liam - Fast Bike Gear) who posted about challenges with a DS update just a few days ago

I'm sure Liam would be happy to discuss the issues they resolved - can be contacted through FastBikeGear.co.nz

Good luck!
Oh shit, this is awesome insight!!

Thank you, I'll forward this onto David @ Rexxer.
 
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