Have been working on this for awhile! No change in any repairs. Engine will start and idle good, but as you increase throttle to 1/4 or more, engine cuts out and revs up and down but doesn't die. If you hold throttle wide open, it will cut out several times and then smooth out, but doesn't seem to be running wide open. Please bear with me as I explain what I've done
Had tps code, replaced it and set with special tool, no change. Found tps plug and short wiring harness has been changed and old one was in glove box. Put old plug back on and soldered connections, no change. Checked fuel psi and found it to be jumping around when engine cuts out. Replaced pump, no change. Replaced psi regulator, no change. During all of this I noticed when I remove ground wire from battery to reset codes, they never reset. Same codes are always there! Now have codes 22, 41, 42
I took machine to another guy who is supposed to be good at diagnosing electrical issues. He told me that the timing is jumping around that's why engine is surging and that several computers could be bad. That doesn't seem right to me, but I'm no expert, especially with efi
Any help will be appreciated

 

Code 22 is air temp sensor. You might pull it from the air box duct clean and reinstall. Item#14. Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse Also what a lot of people over look is the rubber grommet under the map sensor on the intake manifold. Item#9.Dirt Cheap Yamaha, Polaris, Suzuki & Kawasaki OEM Parts & Accessories – Cycle Parts Warehouse If it's split it can suck air and idle will be erratic,will backfire,etc. Plus the main area that the 500s had wasn't in the tps sensor or wiring but the map sensor harness and connector. If cleaning the air temp sensor and inspecting/replacing the grommet doesn't help,I'd still guess that the map sensor harness and connector is the problem even though it may not throw a code 45 or 46. Polaris repair kits are junk,period! I've had to replace these over and over with the same thin wiring and cheap connectors. Wiring can melt internally,pins can pull back from the connectors. If you narrow it down to that you can get a better map sensor repair kit here. Listed under "pressure sensor".Only The Best

 

I was hoping you would be the one to reply!
So your saying I need to focus on the map sensor and harness?
What is your thoughts on the timing. I thought the utv only had 1 ecu, located under the drivers seat
Thanks again

 

Timing is controlled by the ecu and it's usually not a problem.Plus this model has a regulator and not a pdm module that can cause problems. You can check if cam timing is off though by just pulling the flywheel nut and checking if the flywheel key has sheared and if the flywheel has moved on the crank shaft. The 500 was really the only major one to do this. If the flywheel key is ok,not sheared,then I'd say check out the grommet and other things I mentioned.