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Just bought this sled. Sled starts hard(need to open the throttle wide when cold) but it idles good just gets terrible mileage on the trails. I am running 93 Octane no ethanol fuel, and valvoline low smoke snowmobile oil. It smokes a lot at startup and what seems to be more than normal at operating temp. Was told that it might be a bad TPS(Throttle Position Sensor), old fuel, crappy oil, plugged exhaust, or bad injectors. Could someone help me out if youve had this happen or know what the problem is?
 

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First place your running fuel that should be in a 160 plus pound compression engine. Your sled is designed to run on 87 octane. With 93 your pistons are running way to cool along with your pipe. The domes of your pistons are probley shinny as brand new. Your way over octane. Drop down to 87 and see how it runs then. If your worried about the ethanol, make sure the ethanol wire is the way it is sopost to be, UNPLUGGED, Ron.
 

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<div class='quotetop'>QUOTE (omercityman @ Dec 23 2009, 03:23 AM) <{POST_SNAPBACK}></div>
If your worried about the ethanol, make sure the ethanol wire is the way it is sopost to be, UNPLUGGED, Ron.[/b]
X2
 

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Now that I think about it, you are right about it not having a plug... Your computer should change for it if I have heard right. But I could be wrong.
 

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In 96 they had made separate EPROM chips for ethanol, and the chip needs to match the injectors, like the regular, non-ethanol chips.

What kind of fuel consumption are you getting? These sleds are hard on fuel at the best of times, so if you can get 80 miles to a tank then you're doing well. If your plugs and piston wash are showing a rich condition then you should check the fuel pressure in the fuel rail and you may be able to get an adjustable regulator to lower the fuel pressure, which will have the effect of leaning out the fuel delivery. You can tune with that until you get good piston wash and plug colour and that will be the best fuel consumption and power output the thing will make.
 

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I have been through this start at the throttle safety there is a pinned article about that for newbie’s
then check the tps
unplug the connector at the tps with key off
use a ohmmeter test red and black wires at tps should be 4250-6750 ohms
with throttle at idle black and white should test 722.5-977.5 open the throttle
slowly and watch the reading to see that it dose not drop or spike
the reading should be smooth and clime to 4250-6750 ohms at wide open throttle
if this checks ok then the air temp sensor and coolant temp can cause hard start and rich or lean conditions
Have you done a compression test?
mechanical condition should always checked first
 

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fuel pressure should be 36.2 psi
return line can be pinced chauseing high presure reading

check codes the ecm flashes codes with a led on the side of the ecm
 

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Discussion Starter #9
thanks guys, the top end was rebuilt before i got it, and compression is good, pistons werent shiny and clean but had good color, checked tps it is good, and the fuel consumption issue has yet to be checked again because the damn rain that we got the 23rd and 24th of december closed the trails and destroyed the ice on the lake, i will let you guys know how she does when the trails reopen, never thought of an adjustable regulator, and have heard from a couple of people that these things suck fuel bad
 

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i get about 90ish miles on a tank of fuel with my 96 580efi. my 440 getts better milage then my 580
 

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Discussion Starter #11
the guy i got it from had to have had the tps off at some point because it wasnt lined up with the factory "glue" marks, turned it back to where it was and it runs amazing starts easy and just plain out runs better cant wait to get er on the trails, now on to fixing my 1980 El Tigre with a 500cc Free Air that just plain out feels fast.
 

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You are correct in thinking the TPS was out of adjustment. It is the main input for EFI calibration. It measures throttle valve angle (the amount of air entering the engine) and engine load. Now that it has been moved you must be very, very careful that you are not too lean. You can adjust the mixture all over the place with this sensor.

Now drive it easy and check the plug colour and piston wash after running at different speeds and do a plug chop. To adjust it correctly, you need a good DVM and measure the voltage between the center and low end of the sensor with it plugged in and the key on, but the engine not running. You read the voltage at wide open throttle (around 4.25 volts) the higher the voltage, the richer. You run it, check the plugs and then using your meter you adjust richer or leaner. Only adjust about 0.05 volts at a time. The adjustment is very sensitive. By doing this, you can get this sled running good and clean and easy on fuel. They are very rich from the factory. The 700 EFI's can be done the same way. Don't be surprised if you end up at 3.90 volts at WOT.

BP
 

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You are correct in thinking the TPS was out of adjustment. It is the main input for EFI calibration. It measures throttle valve angle (the amount of air entering the engine) and engine load. Now that it has been moved you must be very, very careful that you are not too lean. You can adjust the mixture all over the place with this sensor.

Now drive it easy and check the plug colour and piston wash after running at different speeds and do a plug chop. To adjust it correctly, you need a good DVM and measure the voltage between the center and low end of the sensor with it plugged in and the key on, but the engine not running. You read the voltage at wide open throttle (around 4.25 volts) the higher the voltage, the richer. You run it, check the plugs and then using your meter you adjust richer or leaner. Only adjust about 0.05 volts at a time. The adjustment is very sensitive. By doing this, you can get this sled running good and clean and easy on fuel. They are very rich from the factory. The 700 EFI's can be done the same way. Don't be surprised if you end up at 3.90 volts at WOT.

BP
 

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Discussion Starter #14
Thanks again guys for all your help, and pointers about these adjustments. This is my first experience with an efi sled and compared to my first(1975 Rupp Nitro 440 Fan Cooled) and second(1980 Arctic Cat El Tigre 6000 with the 500 Free Air engine swapped in)sleds working on it is almost impossible without your guy's help.Thanks Again, RJ.
 

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Any way to make proper adjustments to the TPS without the added tools etc.?

I have a 93 EXT EFI, and the harness has no hook up for any test equipment.

Seems my sled is dumping a lot of fuel into the cylinders, which to turn to lean it out a bit?
 

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Yes too much fuel could lean it out.
 

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my 98 is still plugged together, and i run 87 with ethanol should it be unplugged? my sled guzzles gas and i guess about 4 maybe 5 mpg. im going riding today so please let me know asap. my number is 763 772 4844 if you wanna text me your answer or call me. leave aa message. please, thanks!!!
 
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