2015 Yamaha SVHO - Power loss

[rstier]

Very possible your gauge is off. Do you have another gauge to try?
Highly doubtful it's your injectors themselves, but check the wires going to each injectors and coil. There have been issues with the wires breaking at the pins inside the connectors.

I'll check the wires, thanks for the tip. I don't have another gauge but the one I have isn't the best quality and it's possible I didn't seat it tight enough in each cylinder. It was tough to get it tight down there and I didn't want to force it and damage the cylinder heads.

[britpete]

I'm watching this thread closely. I have a 2018 with 175 hours, I checked J hose for boost leakage, checked the intake ribbon for out of position, my loss of power was instant, same max 5-5.5k. When i disconnect each fuel injector and ign coil when running there is a noticeable change in the engine tone. I just bit the bullet and replaced the s/c clutch but it did not fix the issue. I had just changed spark plugs 45 minutes earlier - coincidence?, next step for me is checking fuel injector resistance (spec is 11.5 to 12.5 Ohms), and then swapping coils with a friends 2017. After that cranking compression check. It runs just like its in learner mode, although i have yet to do a recent comparison. My air filter is dry, drivelibe pump all good. Not sure if a faulty reverse switch can cause the ECM to limit max rpm like this?

[K447]

… I had just changed spark plugs 45 minutes earlier …

Install another set of new spark plugs, purchased from a different supplier.

Sometimes a new spark plug can simply go bad.
Sometimes a box of new spark plugs may be counterfeit.

It is not expensive to try another set of spark plugs.

[seabrook]

have you guys tried riding it with the seat off?

[rstier]

I haven’t. What’s the thought there?

have you guys tried riding it with the seat off?

[britpete]

I just checked all fuel injectors. 12.6 ohms each. All wires and connectors look good. Will grab some new spark plugs next. I did not that plug Groups was corroded on top whilst others were clean and dry. After riding this new Groups remains clean and dry

[britpete]

Plug#4 corroded that is...

[seabrook]

I haven’t. What’s the thought there?

if you have an exhaust leak it will limit your rpms with the seat on

[rstier]

Ok, I’ll give that a shot too. Thanks!

if you have an exhaust leak it will limit your rpms with the seat on

[seabrook]

Ok, I’ll give that a shot too. Thanks!

you are welcome man! Also thanks to you for replying back on everyones comments!!!!!!!!!!!!!!! it helps someone later trying to fix a problem

[britpete]

small update on my diagnosis. With all fuel injector wire connectors disconnected, all spark plugs out, 120 psi-ish across all when cranking from cold which i believe is just fine, shop manual states when warm > 70 psi. My knock sensor resistance is under spec @ 430 kOhms, spec is 504 to 616 kOhms, not sure if that is cause for concern. I just replaced all spark plugs, will water test in a couple of days, there's only one dealer here that can water test and they are 2 weeks out from starting on it.

[britpete]

New plugs. Same. Seat off. Same. Learner mode max rpm is lower at 4750. Revs to 8000 out of water with no load. Coils?

[rstier]

New plugs. Same. Seat off. Same. Learner mode max rpm is lower at 4750. Revs to 8000 out of water with no load. Coils?

Same deal with mine on plugs, seat, learner mode (RPMs a little less) and it is able to red line out of water with no load. Did we rule out cleaning the fuel injectors? I haven't tried that yet.

[seabrook]

at this point id take my jtube off, start it and blip the throttle to check if you are actually getting boost (I don't think you are) also the tube is 8 years old and could be cracked leaking boost. if yes then the next step id take is make sure the vent to the fuel tank is drained- but usually a fuel starvation will cause surges in your rpm

[britpete]

I will say that after a short idle then switch off I cannot hear any 'intertia after run' in the supercharger drive, I just listened to my freinds FZR and when that switches off there is some running noise from the supercharger for a couple seconds, mine use to do the same.......