The quad seems to run better each time out, though just on the neighborhood streets. It starts okay, and idles better, but still a little erratically. Will put some miles on it in the Santa Rita Mountains south of Tucson next week.

Maybe this thing really did have only 20 hours on it since 2008 and it was gummed up. Replacing the oils made a huge difference in the drive train-now it's smooth and quiet. The secondary clutch cracks may be only superficial, but I'll post if it flies apart.

Regarding the fault codes: 42, 41, 22, 55 (eng temp, air temp, tps, MIL) - I can't make them go away. Thought I was on to something (my previous post) but the continuity was good from the sensors to the common ECU pin. Should I care about the codes if it runs okay? Will probably take it in to the dealer for an opinion.

Edit: Could one of the 3 sensors be bad and cause the other codes to trip, since they share pin 46 on the ECU?

 

Only thing you can do at home is unplug the battery and leave it disconnected over night. If it still retains the codes, then having it hooked up to Digital Wrench is about the only way to remove them or find out what may be doing this. A lot of tail chasing if you don't. Worth the 1 hour labor charge(in most cases) to trace down a persistent problem.

 

Last outing in the mountains the bike ran okay, but still had the erratic idle and would stall when coming to a quick stop. Finally took it to the dealer--they had it for two weeks. They said the TPS needed to be replaced. Then they said they were having trouble starting it and advised the starter solenoid needed to be replaced.

I picked it up yesterday and all the codes are gone. Yay. The idle is still a little erratic, but better. Took it out to see if I could make it stall with the quick stops and it never stalled once, so that's a good sign.

Side note: I aligned the front wheels yesterday because it was pulling left. I noticed the right handlebar was about an inch lower than the left. Another clue that the bike may have been rolled (along with cracked dump bed). This may have something to do with the engine performance.

Next: Replace the spark plug and adjust the valves. Anyone know if I should replace the fuel filter? It's got 62 hours and 680 milles on it (40 and 500 since I bought this off Craigslist in September this year). So it mostly sat for the past 5 years if the instrument cluster is the original.

 

Glad it's running better and the codes have been removed. If the erratic idle becomes worse or starts popping back,don't forget the stronger tbap and tps harness repair kits that are available.Only The Best

 

So, let me update this thread and describe my continuing issue as "erratic engine operation at lower RPMs." Though the gauge doesn't show the variation, I can hear the RPM fluctuate between almost stalling and about 1600 RPM. I can rev the engine and it will return to idle, but when riding when I apply the brake to come to a complete stop it will often stall. That is the problem.

I put a thin shim between the throttle cable guide/pulley and the stop screw (on the throttle body) to increase the RPM to about 1600, and the engine still operated erratically at that higher RPM. Paperwork says the valves were adjusted at 20 hours in 2008 (It showed 26 hours when I bought it in Sept. 2013 and it's got 77 hrs on it now). I decided to do a compression check and got only 55 psi. This is below the service manual spec of 60-90. Could this indicate a problem that may cause the symptoms I've described?

What should be my next move? Thanks in advance for any suggestions.

 

Replace the map sensor harness kit from OTB!! This was the most consistent problem we had on efi machines as far as idle. Erratic idle from almost dieing to surging,back firing,etc.Almost never a sensor problem just the thin wiring breaking internally or bare spots. Don't tamper with the throttle slack or setting to compensate for a poor/erratic idle.The map sensor wiring or connector itself is the problem.Very seldom a map sensor or tps sensor itself was the cause.We replaced too many Polaris harness repair kits that didn't hold up caused they used the same thin wiring. # OTB 500-05-12. Only The Best Compression reading is normal. Between 55 to 90 psi on average. Some a little less,some a little more.

 

So, my next step was to check the valves, and guess what? I'd never done valves before but it wasn't that big of a deal. Just takes time to prep, do it, then put it back together: about 4 hours.

The shop paperwork from the original owner stated the valves were adjusted after initial break in, which is recommended maintenance. Since the quad was such a low hour machine, it took me a while to finally decide to check them.

The intake valves were way loose, and the exhaust valves were tight. I'd guess they were adjusted without the piston at top dead center.

After I adjusted them and fired it back up, it purrs like a kitten. No stalls. No erratic idle. It's all good.

 

Glad you finally found the problem and found a dealer NOT to take it back to for service if they're the ones that had it for two weeks and are the ones that adjusted the valves which in all probability didn't need it. Most 500 valves are actually set a little loose from the factory. Closer to .007 than than .006 required on the intake and exhaust. I've checked machines a couple years old or older and 90 percent of the time the valves were still spot on.Some of these so called mechanics need to be assembling bicycles at Walmart and leave any thing more technical to real mechanics.. Had to vent on this one...