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Discussion Starter · #1 ·
Hello im going to start off by saying that i own a 2007 sdi. The sled has got a recent rebuild with only 1000 miles on it. My problem is that after it gets warmed up it likes to back fire. It does this pretty often after a hard run or letting off the throttle. Its very easily seen at night with the blue flame shooting out of the exhaust. I called the dealer and they said thats what all sdis do but i have a hard time believing that anyone would by a sled that backfires at every stop sign.
 

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my sled does it often... what happens with 2 strokes is guys like you and I are running them hard, then you shut the machine off or come to a stop. what happens is the unburnt fuel being dumped into the exhaust is ignited by the cherry red expansion pipe thus creating a backfire.
 

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SDI have few sensors that can cause some issues. Exhaust sensor i had issues with a couple times and the knock sensor and air pressure sensor once.

Best way to see get the machine hooked up to the shop computer for a BUDS diagnose.

In the meanwhile I would go through and check all the ground and wiring connections and connectors.

Grab the 06 manual here you will want to review the SDI ECM section:

http://www.snowmobilefanatics.com/forums/13-performance-tuning-shop/100092-snowmobile-manuals-lots-them.html
 

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When riding at night stop to open the side panel to see the colour of the muffler.
 

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I have had 3 600 ho sdi's and not one has backfired. I have an 07 right now with 6400 miles and it still runs like a top and don't backfire. I'd say the dealer you spoke with is waiting for yours to blow up so he can rebuild or sell you a new one. Don't believe for a sec that their suspose to do that. The best thing to do might be to take it to the dealer and have them hook it up to the computer.
 

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I have had 3 600 ho sdi's and not one has backfired. I have an 07 right now with 6400 miles and it still runs like a top and don't backfire. I'd say the dealer you spoke with is waiting for yours to blow up so he can rebuild or sell you a new one. Don't believe for a sec that their suppose to do that. The best thing to do might be to take it to the dealer and have them hook it up to the computer.
The dealer that the OP spoke to is not crazy, I can assure you of this. An SDI backfiring is a well established problem, and yes it can be corrected. The first thing one needs to do is ensure the complete fuel system is in order, including the injectors, and the tps is set correctly. The system voltage on an SDI also needs to be top notch. 14.0 Vdc is not a well running SDI, any SDI engine. The Crank Positioning Sensor and Ignition Coils also needs to be working correctly, as well as the rave valves. If the problem persists then the owner has the choice to upgrade the software to eliminate the problem. Personally I prefer to stick with the older maps which have some problems, but when running right they are very impressive. Think 2010.5 ETEC 800 vs 2011-2014 ETEC 800s. I don't have studs for a good launch, but once I get going you will have a difficult time to keep up regardless of the engine under the hood.
 

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Im riding tonite so ill check. Daag your pretty knowledgeable about these sdi's what do you think?
The first thing that comes to mind is the folks who contributed to this topic are very knowledgeable and I count on their experience for a good solid benchmark. I have only run the 2004 fuel/ignition map, so my understanding is limited to my experience and what I know of the SDI. I did what I could in post #9 to show what I know and hopefully it will help. I started a topic on preseason maintenance for the 2004 600 SDI hoping it would help show the many things that can be done by the owners. What you can do yourself is mind blowing with the only limitation is your perception. Having said this, the 2007 ignition/fuel map should have no problems with backfiring. This problem and others have been corrected by Ski-Doo with the MY2006 calibration file 420 665 199. The other members were correct, you should not be experiencing backfires. This is actually very good news. In other words, unless your sled was fitted with an older ECM, you should have no trouble correcting the problem. But it will need the right tools to do this at home which happens to be to your advantage. Hope that made sense.
 

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Discussion Starter · #11 ·
How is it at idle? My thought is bad intake gaskets/boots. Machine will dump gas when this happens causing backfire.
Idles perfect and starts within the second pull, sometimes dies when cold but starts right up afterwards. Throttle response is perfect and there is no irregular idling at stop signs.
 
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