No spark on cylinders 2 and 3

[Lawton21]

Join Date Sep 2017 Location Peterborough NH Posts 27 No spark on cylinders 2 and 3

I have a 2003 Yamaha vmax hpdi that would not get over 2000 rpm. I brought it to my local mechanic who is not yamaha certified ( the closest Yamaha tech is pretty far away) and he diagnosed the issue as bad injectors on cylinders 2 and 3. Replaced those and that fixed the injector problem but now it doesn't have spark over 2000 rpm on those cylinders. He said it was probably a bad sensor that would have caused the injectors to go bad and it needs to be plugged in to diagnose the sensor. All six coils are good as he switched them around and they all had spark. He also tested throttle position sensor and that was good to. I'm going to take it to the Yamaha tech this week, but does anyone know what this may be, or what I should expect? Fuel system and compression are all good as well.

[99yam40]

HPDI motors do not run some cylinders while idling in neutral.
if you raise the throttle while in neutral the ECU shuts off other cylinders trying to keep the RPM down.
even if you put it into gear but the ECU thinks it is still in neutral it will try it's best to stop the RPM from rising

[Lawton21]

I knew hpdi motors shut down cylinders while idling in neutral. It sounds like the ECU still thinks I'm in neutral when I'm in gear. What sensor would cause that.

[boscoe99]

Not a sensor. It is the shift position switch.

[Lawton21]

Changed out the shift position switch and now it has spark and runs well. This was the first time out since I got it back from the and now while idling in neutral it occasionally cuts out for a second and then comes right back. It actually shut off at one point but idles fine in gear. Could this be a tps adjustment or something else?