Hole in Air box on the Engine side of Airbox. Check yours

[Glenn Yingst]

I have been dealing with a Random missfire on my 2016 Stelvio NTX for over a year. It started at around 12000km and went un-diagnose until 27000km. Poor idle, surging and hunting . I finally left it at the dealership with instruction that I didn't want it back until it was 100%. They thought It might be the idle Stepper motor and finally got approval from Piaggio to replace it. Upon disassembly to install the Stepper motor they discover a 1 1/2" hole in the airbox under one of the rubber tubes connecting the TB to the airbox with excessive dirt and sand in the airbox. So the Tech checked a 2016 Stelvio sitting on the show room floor and guess what, same hole same location. They checked another customers 2016 Stelvio in for service and it did not have the hole so its not a consistent defect.
(Now I had noticed excess sand and dirt in the airbox when I serviced the Air filter at 15000km. and let the dealer know, I was told I likley didn't get the airbox sealed when I last check the filter. So I replaced the Airfilter and made sure the airbox was sealed correctly.)

Anyway there had been so much dirt passed through the throttle bodies that they where worn out and would not seal when closed. This would explain the hunting and surging as the stepper motor was trying to compensate for the extra air present on the TB side of the filter.
Once the Throttle Bodies had been replaced and the hole patched Stelvio runs and idles as it should. I have requested extended warranty from Piaggio and they are dragging their heals. 11 emails so far back and forth and still nothing yet.
Common sense would dictate that if there was enough dirt passed through the TB that they wore out .... That dirt also went through the motor!

I still think the Stelvio is a Great Motorcycle and Love it but I have to say I'm not impressed with PIAGGIO!

will post and update when I hear back

 

[Raven]

If the dirt was on the outside of the filter in the air box then the engine may not have ingested any. A goodwill warranty extension would be nice considering yours is not the only one with this issue.

 

[Glenn Yingst]

If the dirt was on the outside of the filter in the air box then the engine may not have ingested any. A goodwill warranty extension would be nice considering yours is not the only one with this issue.

I should have described it better. the Hole is on the Motor side of the Filter. So un filtered air and dirt was going through the throttle bodies and into the motor.

 

[GuzziMoto]

That is bizarre. Did the hole look like it was made to be there? Was it perfectly round with smooth edges?
That just seems very odd. Is there some version of that airbox where there is a fitting there for a hose or tube?

 

[Glenn Yingst]

The hole is a mold or casting defect, Not symmetrical. And the weird thing it isn't on all Stelvio's . I was thinking the air box comes from a out side supplier , they should have caught that on assembly.
Still waiting to hear back from Piaggio!!

 

[steveoh]

I just found the hole on my 2016 Stelvio as I’m trying to track down a terrible idle problem. I am furious as this bike is long out of warranty.

 

[lemans850i]

Did you make or get any pictures of it???

 

[steveoh]

Yup.

 

[tris]

Sounds like the goods inwards inspection at the factory isn't up to scratch.
To follow the theme, I found that 2 out of 2 Breva 1100 clocks I looked at had one of the vents in the back blocked with plastic in the wrong place.
Good news was that carefuly sticking a drill through it removed the misting problem I had.
Sadly the same can't be said for this issue

 

[steveoh]

I was eagerly looking forward to see the new Stelvios but I seriously have doubts. This is basic QA, nickel and dime parts, and inspection could prevent major damage.

 

[lemans850i]

Well, at least I can show my wife a reason why i sit in front of the motorcycle and look at it....
Quality control....

 

[GTM®]

I just found the hole on my 2016 Stelvio as I’m trying to track down a terrible idle problem. I am furious as this bike is long out of warranty.

Thanks for reviving this thread and the photos. I’ll be more vigilant in checking all we see in my shop. This is certainly a VERY frustrating situation, sorry to see and hear. We have also seen a handful of newer NTX that have excessive freeplay in the throttle (butterfly) shafts. Now I wonder the correlation between both this and those. If you grab the linkage arm/shaft where it goes into the throttle body on either side, do you have any visible side to side movement when wiggled?
Excessively worn shafts will exhibit idle issues and sneezing at idle. Most think it’s the stepper motor.

 

[steveoh]

I have no extra play in linkage arm.

I suspect the carbon canister. Disconnecting the TB hoses at TB and linking hose between them shortly.

 

[GTM®]

Ok, not in the arm, but in the shaft itself that goes through the throttle body.

 

[Vagrant]

Throttle shafts are a much higher wear item then people imagine. Any slop at all and it's a major air leak destroying fuel air mixtures. Very common in small engines.

 

[ZClark73]

Hey all! I didn’t find this exact problem, but I did recently find the bottom drain tube had broken off, the side drain tube was not connected and the airbox was splitting at the weld seam! Sheesh. Make sure the check this seam if you’re pulling the airbox!

Included pictures are the seam failure, then the hose on the bottom that completely broke off, then the side port. Final picture is what the bottom drain line looked like from the side of the bike with nothing disassembled.