92' Polaris RXL Hot Misfire Issues
I have a 92' polaris rxl EFI 650 and I am hoping some RXL veterans can give me a hand with this one, here is the specs. All stock, with a fresh engine rebuild. Excellent compression, all castings machined (stock c.r recut), new crank, seals, ect. Clutches have been rebuilt, alinged and belt deflection adjusted. Fresh NGK BR9EIX's installed with excellent spark. Throttle bodies are sync'd and idle at 2200 rpm. Here is the problem- Cold engine, two pulls and it fires up, high idles great, warms up and idles down, has full power and responsiveness for 15-20 mins of ride time. Then quite consistantly (every ride attempt) the engine will have basically no 0-25% throttle response (will die if under 1/4 throt.) and when throttle is applied +25% the engine surges and back fires with short bursts of power. The sled is able to continue back to shop under its own power but once it cools down it again runs normally. I am getting a crank case temp code on ecm. and i replaced sensor and checked wire (which was on good). If the engine was carb i would have checked stator and cdi. But im am unsure if this is a ignition system problem or a efi lean/rich issue. Before i tear into it id like to get some EFI experts opinions! Thanks! Jeremy.