This is a description about how idle problems were solved on a Polaris Sportsman 500 EFI 2007. I hope this post can be helpful to members of the forum and others.
I bought a used Polaris Sportsman 500 EFI year 2007 in November 2011. It only had 6 hours on the meter an had obviously been sitting a lot. After i had run it for a few hours i started to have problems with the idle. The problems can be divided into three.
1. Sometimes the machine did not want to idle at all. It died when i released the throttle, sometimes this happened immediately or after a few seconds of idle.
2. Sometimes the idle stuck at around 1600 rpm and did not come down to correct level about 1140 rpm.
3. When it did idle the idle wasn't very stabile. It went up and down between 1100 – 1500 rpm.
Problem number 1 was quite easy to fix. The throttle cable tension was to loose causing the contacts in the ETC switch to make contact. This is a safety mechanism that prevents the engine to run if the cable is stuck with the throttle in open position. But this also happens if the cable tension is to loose. I tightened the cable tension and problem number 1 was fixed.
Problem number 2 and 3 were more difficult to solve. I checked all wiring from the IAC, the TPS and the MAP sensor to the ECU. Found that the insulation on one of the cables from the TPS was broken. Ok here we have it i thought. I isolated the wire but the problems remained. Then i tried cleaning the IAC and the MAP sensor and all connectors. It did not help. I bought new (used) IAC and MAP sensor. No luck. Finally i bought the TPS test connector https://polaris.spx.com/Detail.aspx?id=182
. With this tester and a multimeter i could se that there were jumps in the volts on my TPS when i moved the throttle from closed to wide open. I bought a new (used) TPS and problem number 3 was solved. The idle became stabile at around 1180 rpm.
Problem number 2 still remained unsolved and no matter what i did i couldn't fix it. On this forum i got an advice from AKStew that the problem might be mechanical and not electrical. That lead me back to the throttle cable again and i started to check on that. I checked that the throttle cable and housing moved freely and lubricated the cable. Then I opened the throttle case cover. I checked that the throttle wheel moved freely and that it made contact with the stop screw when the throttle lever was released, it did. I lubricated the wheel and then I got an idea. Instead of putting everything back together I only put one of the three screws that hold the throttle case cover back, thinking if I leave it with one screw only I can easily check the position of the throttle wheel when the idle get stuck. I went out driving and after an hour or so it happened, the idle got stuck at 1600 rpm. I forced the neutral in and jumped of the machine and unscrewed the single screw that held the case cover. Inside I could see that the throttle wheel made contact with the stop screw. Everything looked fine but then with a screwdriver I manually pushed the throttle wheel back against the stop screw. I heard the idle decrease just a few rpm, I pushed harder and then whoops the idle sunk to correct level 1180 rpm and stayed there also when I stopped pushing on the wheel. So the stop screw was too high. Now, in Polaris workshop manuals there are plenty of warnings about adjusting the stop screw yourself. According to the manuals the stop screw is set at the factory and should not be adjusted after that. So instead of adjusting it i cleaned the entire throttle body with break cleaner thinking that dirt might prevent the butterfly to close completely. That did not help. So despite the warnings about the stop screw i decided to turn it down one millimeter. And after that the problem disappeared.
Everything took six months of, fixing, thinking and testing before all problems were solved. Its worth to mention that i know of one other identical machine and year (Polaris Sportsman 500 EFI year 2007) that had the same problem with the stop screw, so maybe this is a common problem of that model and year.
Thanks for advices i got in this forum during the process!