08 Sportsman 500 EFI backfires and no trouble codes showing
 

I have a 2008 polaris sportsman 500 EFI. It has around 350 miles on it and when you first start it up and back it out of the shed and put it in high to go forward it dies. Even in neutral reving it up it has poor throttle response and it "pops" back through the intake. I have had it to the dealer twice. They hooked to their computer and found everything to be with its ranges. It backfires even when sitting in my 70 degree shop. I put better fuel in it and it seemed to help, I think the gas in my farm barrel is getting crappy. I have called two other dealerships and they dont have a clue. My dealer did fix a broken wire an, changed the resistor and spark plug and it helped alot but it isnt that great. I can jump on a fuel injected honda at 0 degrees it takes right off. My dealer does not know what to do as the machine is not throwing a code. I think the timing is off or a sensor is lying to the computer. Please help!! I am at my wits end. Otherwise I am more than happy with the machine. Thanks for any help.

is there water in the gas? i'm assuming he cheched to make sure the etc is set right as well on the throttle. how did the plug look that came out of the bike? welcome to the forum.

I am not sure of all the computer told him. He said the TPS was needing adjustment and he did that. The fuel in it is brand new 91 octane which helped a little. What is your Polaris EFI machine like? Can you start it up cold wait a few seconds and then open it up all the way. I rode a brand new honda when it was zero out and it did not miss a beat. I am so frustrated. The dealer said that the only thing he could do was to start replacing sensors and other parts. The machine is out of warranty and I emailed polaris but I doubt they will stand behind it. What do mean about the ETC? I know what it stands for but was wondering technically what it does and how much to replace it? What are other polaris EFI machines like? It had about 1 gallon of old gas when I added the new gas. Whould some sea foam help? lucas injector cleaner? Someone told me that it sounds like the machine is running to lean but it has plenty of power to pull stuff. The spark plug was black so they replaced it. I am guessing after a few times of backfiring in my shop it will be black again.Please expand on the ETC and how it can be screwing up the machine, and as always PLEASE HELP!!!! Lol. Thanks for all the help.

my efi is fine in cold weather as far as running not too bad. once you start it, it might take a minute to warm up to go and take right off. the ETC = eletronic throttle control is adjusted right at the handle bar in the throttle housing. basicly it has to have about 1/8" slack in the throttle cable before you actually feel the throttle being pushed and this is to prevent the bike from having a frozen throttle and it will go into a override mode and not letting the bike run. when you put the gas in, did you check to make sure there wan't any water int he tank by actually looking for the bubbles? sea form wouldn't hurt and to help clean the tank out. back firing does sometimes mean a lean condtion, but the spark plug would be a white color. check the intake boot for cracks or other air leaks to explain the lean condtion if it has one. stupid s it sounds, it might be something simple but hard to find.:huh:

Can the fuel injection be adjusted richer to compensate the lean condition? Do you think that the dealer is right about starting to replace components and sensors. Do you think it could be the ETC? What else can I look for? Could the ETC be malfunctioning, telling the bike to cut out but then coming back on? Thanks for the help

The most problems we have are not the sensors,but the connectors and harness problems,especially on spitting back,erratic idle and such. If the dealer readjusted the tps correctly,the etc slack is ok,I would suspect the the tps or t-bap(map) sensor short in harness or in the connector itself. They usually wont show up on the codes,sometimes they will show up on our computer digital wrench,but not often. You can visually check the small wires from the sensors for rubbing and chafing,but not always visible. Tps and map sensor kits are available. One other area to check is the crank sensor harness where it rubs against the back of the starter,have had a couple problems in this area also. OPT

good advise and areas to check ^^^.

Old polaris tech- Can you be more specific of the locations of sensors and plugs I should check?

Map sensor located just behind the fuel injector on the throttle body,the tps sensor on the side of the throttle body,and the crank sensor harness and connector by the back of the starter motor,wires come from recoil housing area.