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2012 WR450 with cruising stutter/surge, please help!

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I have a 2012 WR450 with a street legal supermoto set up that is experiencing a low rpm stutter/surging. Like many other later WRs, it occurs while cruising at less than 1/4 throttle.

Info on current set up:
-FMF Q4
-GYTR Competition ECU - base GYTR tune for FMF exhaust
-Air box unrestricted, snorkel removed
-CO set to 7
-TPS adjusted to output voltage of 0.75v

The stuttering/surging has occurred since the day I purchased the bike (used) with 1,000 miles. I understand the dynatek or vortex ignition modules were the solution for later year carbureted bikes to resolve the ignition from jumping between settings below 3000 rpms.

After some research, it sounds like this is not very common on the 2012+ fuel injected bikes as I cannot find any information. Has anyone else with a 2012+ WR450 experienced this also?

Edited by dan161

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Never heard of any such symptoms on any FI version WR's. 

I would change the plug,   inspect the cap/coil, and check all ground points, especially the stator harness and the accessories ground points.

Do you have a stock battery ?

Try running a 10ga wire from the battery to the starter ground...

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1 hour ago, Krannie McKranface said:

Never heard of any such symptoms on any FI version WR's. 

I would change the plug,   inspect the cap/coil, and check all ground points, especially the stator harness and the accessories ground points.

Do you have a stock battery ?

Try running a 10ga wire from the battery to the starter ground...

Yeah I was surprised the first time I rode the bike as it was in excellent condition. My first thought was the TPS so I checked voltage. Going to grab a new plug on my way home tomorrow and check grounds.

The bike has a Shorai Lithium Iron battery.

Edited by dan161

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I'm guessing you already tried playing around with fuel mapping since you have the gytr ecu..?

 

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On 4/30/2017 at 10:59 PM, dspy21 said:

I'm guessing you already tried playing around with fuel mapping since you have the gytr ecu..?

 

Yes, I'm currently running the base tune from GYTR for an FMF exhaust. The tuner only effects fuel and timing above 3000rpms and the issue I am having is cruising at constant speeds in mostly 4th and 5th gear with rpms at or less than 3k or 1/4 throttle.

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On 4/30/2017 at 8:38 PM, Krannie McKranface said:

Never heard of any such symptoms on any FI version WR's. 

I would change the plug,   inspect the cap/coil, and check all ground points, especially the stator harness and the accessories ground points.

Do you have a stock battery ?

Try running a 10ga wire from the battery to the starter ground...

I swapped out the plug tonight and other than some corrosion on the exterior, the plug had a clean burn and no signs of lean or over fueling conditions. The WR appears to have only one main ground, correct me if I'm mistaken, at the back of the starter and splices that web off to various other accessories. The connection at the starter and negative battery terminal were clean. I also pulled the ignition coil and cleaned the contact areas with the frame.

I took it for a ride a few minutes ago and the stuttering/surging continues. Any other suggestions?

Edited by dan161

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1 hour ago, dan161 said:

I swapped out the plug tonight and other than some corrosion on the exterior, the plug had a clean burn and no signs of lean or over fueling conditions. The WR appears to have only one main ground, correct me if I'm mistaken, at the back of the starter and splices that web off to various other accessories. The connection at the starter and negative battery terminal were clean. I also pulled the ignition coil and cleaned the contact areas with the frame.

I took it for a ride a few minutes ago and the stuttering/surging continues. Any other suggestions?

sucks it didn't work, don't ride the bike at <3k rpm's maybe

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10 hours ago, dan161 said:

I swapped out the plug tonight and other than some corrosion on the exterior, the plug had a clean burn and no signs of lean or over fueling conditions. The WR appears to have only one main ground, correct me if I'm mistaken, at the back of the starter and splices that web off to various other accessories. The connection at the starter and negative battery terminal were clean. I also pulled the ignition coil and cleaned the contact areas with the frame.

I took it for a ride a few minutes ago and the stuttering/surging continues. Any other suggestions?

Yes, inspect the stator pick up for debris on the magnet.......pull the fuel pump and clean the filter.... then pull the injector and do a pressure cleaning.

The only thing that can create the stutter is poor atomizing at a specific injector pulse frequency, or a compromised electrical system (ecu, stator pick up etc) 

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