2014 SR Viper hard starts cold/ won’t idle

[SRXSRULE2]

The stalling issue happens generally while riding and say you’re coming to a road crossing and you let off the throttle it dies like someone hit the kill switch. When I checked the throttle block throttle switch it checks out okay.
If I started the sled today, it would idle okay for maybe 20-30 seconds and then the idle speed drops to 13-1400 rpm. During this time if the throttle isn’t touched it will sit and run all day but the idle is too low and it’s running so rich you’d think it was a 2 stroke. Plugs all look the same dark wet.

Trying it with ether, when getting it to stall it happens so fast it wouldn’t even have time to get in the air box. I have checked the boots on both sides of the throttle bodies and there are no issues there. Tried it with propane to see if they were leaking, nothing. No vacuum leaks that I can find.

Fuel pressure is 46 psi on my gauge, it’s a matco gauge. Yea it’s off by 2.5 psi but likely it’s just my gauge, it’s been dropped a few times over the years. The best part is the manual asks to check the return line for restrictions, yet it is a returnless system?

Map sensor reading, unfourtunately that isn’t displayed on the gauge. I previously disconnected the map sensor, hooked it up to a vacuum pump/gauge and checked it while back probing the sensor and the voltage changes smoothly like it should. I’m not sure if Yamaha has a diagnostic tool that has data display or not.

 

[Allan]

The stalling issue happens generally while riding and say you’re coming to a road crossing and you let off the throttle it dies like someone hit the kill switch. When I checked the throttle block throttle switch it checks out okay.
If I started the sled today, it would idle okay for maybe 20-30 seconds and then the idle speed drops to 13-1400 rpm. During this time if the throttle isn’t touched it will sit and run all day but the idle is too low and it’s running so rich you’d think it was a 2 stroke. Plugs all look the same dark wet.

This sounds just like mine when the valves were out of spec. I had 18000 km then.

 

[SRXSRULE2]

This sounds just like mine when the valves were out of spec. I had 18000 km then.

When the valves were out of spec, what was found? Was the clearance too tight? Too loose? How far out of spec was it?

Reason I’m asking is that valves have been mentioned a lot, but when I checked them they are still within spec but they are on the tight side of the spec.

 

[Allan]

When the valves were out of spec, what was found? Was the clearance too tight? Too loose? How far out of spec was it?

Reason I’m asking is that valves have been mentioned a lot, but when I checked them they are still within spec but they are on the tight side of the spec.

Mine was done under warranty so I not sure what they were. but all my exhaust valves were out of spec on the tight side and I think one was tight and the rest were out of spec.

 

[cannondale27]

And dont forget the 16-17flash was known for a random stall. Not all the time though. You positive its not the clutches sticking or too tight deflection?

 

[SRXSRULE2]

And dont forget the 16-17flash was known for a random stall. Not all the time though. You positive its not the clutches sticking or too tight deflection?

Never heard about the random stall, it will hopefully be going in this week to get the latest flash.

It will do it even with the belt off. It broke a primary spring a couple years ago and even then it never stalled? Clutches were gone through last season though, the track doesn’t creep when it’s running on a stand.

On a side note, I wonder what they have done with this latest flash as the feedback has been good.

 

[cannondale27]

Never heard about the random stall, it will hopefully be going in this week to get the latest flash.

It will do it even with the belt off. It broke a primary spring a couple years ago and even then it never stalled? Clutches were gone through last season though, the track doesn’t creep when it’s running on a stand.

On a side note, I wonder what they have done with this latest flash as the feedback has been good.

Not sure what they did. We may never know. But it's about time they did it!

 

[Bobsledder]

I have the same problem with my 2014 viper. I had it in under warranty to fix this 2 times and they found nothing wrong with it. My IAC reads 60 off idle and is at 120 most of the time at idle. It will sometime hunt back and forth 110-120 when totally warmed up. It will never stall after completely warmed up. The annoying problem was it would never keep running at idle when starting cold. This started happening at about 6000 miles. I always would have to hold the throttle open slightly until the ECT Temp would be greater than 60F and it would then idle on its own. I have verified IAC movement with no blocked IAC passage. I put in new Iridium plugs last year and it did nothing to fix it. I did do one thing that fixed the stalling at cold start. I moved the Idle stop screw that controls the min air around the throttle blades by watching the TPS voltage and moved it from .6 volts to .7. The throttle blades were also cleaned before I adjusted the throttle stop. I think or IT IS Running way TOO RICH after it starts and needs more air than the IAC can give. The start calibration on this sled has always been terrible. I also have pretty much ruled out belt deflection also. I put on a very worn-out belt that is my spare and it will also stall with that belt on. Both clutches also have been totally rebuilt by the dealer when this stalling problem started. Once the sled it is totally warmed up, it runs great and does not stall. I never checked the valve clearance. I have changed the oil religiously and it always comes out looking like that's another $20 bucks wasted. If the valve clearance is off, I came from the factory that way. I also ran the yamaha combustion cleaner fuel system additive that was suggested and that didn't fix it. Another side note is the dealer also told me that some of their rental vipers start much worse than others for no know reason?? They have done a terrible job on the start calibration. Good luck. I would consider an after market flash calibration if one exists that will fix this.

 

[74Nitro]

I have the same problem with my 2014 viper. I had it in under warranty to fix this 2 times and they found nothing wrong with it. My IAC reads 60 off idle and is at 120 most of the time at idle. It will sometime hunt back and forth 110-120 when totally warmed up. It will never stall after completely warmed up. The annoying problem was it would never keep running at idle when starting cold. This started happening at about 6000 miles. I always would have to hold the throttle open slightly until the ECT Temp would be greater than 60F and it would then idle on its own. I have verified IAC movement with no blocked IAC passage. I put in new Iridium plugs last year and it did nothing to fix it. I did do one thing that fixed the stalling at cold start. I moved the Idle stop screw that controls the min air around the throttle blades by watching the TPS voltage and moved it from .6 volts to .7. The throttle blades were also cleaned before I adjusted the throttle stop. I think or IT IS Running way TOO RICH after it starts and needs more air than the IAC can give. The start calibration on this sled has always been terrible. I also have pretty much ruled out belt deflection also. I put on a very worn-out belt that is my spare and it will also stall with that belt on. Both clutches also have been totally rebuilt by the dealer when this stalling problem started. Once the sled it is totally warmed up, it runs great and does not stall. I never checked the valve clearance. I have changed the oil religiously and it always comes out looking like that's another $20 bucks wasted. If the valve clearance is off, I came from the factory that way. I also ran the yamaha combustion cleaner fuel system additive that was suggested and that didn't fix it. Another side note is the dealer also told me that some of their rental vipers start much worse than others for no know reason?? They have done a terrible job on the start calibration. Good luck. I would consider an after market flash calibration if one exists that will fix this.

I assume you have checked the alignment marks on the stub shaft?

Also, why do you say that the valves would have been like this from new, but the problem started happening at 6000 miles.