If you were one of the owners of a 2011 Arctic Cat sled equipped with the 800 H.O. engine and burned 91 octane fuel, you might have been surprised to occasionally experience “Limp Mode” (indicated with the “OCTN” code on the speedo, a 7700-rpm ceiling and extra-rich fuel/air mixture).
The situation confused more than a few riders (including me), who were certain to have used the required 91 octane fuel.
The problem wasn’t octane. It was ethanol.
When Arctic Cat calibrated the EFI system for 2011, engineers couldn’t factor some of the high concentrations of ethanol that exist in certain regions of the country. At partial throttle positions at elevations between 0 – 3,000 feet AND where there was very little load on the engine, the addition of lean fuel (because of high ethanol content) caused knock/detonation.
When the system detected detonation, it automatically retarded the engine timing. If this didn’t stop the detonation, it activated the Limp Mode, which limited rpm to 7700 and increased the amount of fuel to the mixture to prevent damage to the engine.
The engine stayed in limp mode until it was reset (whenever the engine is restarted).
The problem was, in some areas of the snowbelt, poorly-blended 91 octane fuel was the norm, and thus riders dealt with Limp Mode more frequently than what was desirable. When Arctic Cat became aware of the situation, members of the engineering team went to work on a fix.
The Fix Is In
Arctic Cat recently notified registered owners of these sleds that authorized Arctic Cat dealers can reprogram their engine ECU at no charge, to eliminate the poorly-blended/ethanol fuel-induced detonation.
Three recalibration strategies were involved to eliminate the glitch:
1. Change the fuel injection timing strategy: Not the amount of fuel, but when the injector is fired based on crank angle.
2. Recalibration (the amount of fuel and ignition timing) in partial throttle areas when the APV exhaust valve is in the down or middle-position. FYI: There are three APV valve positions.
3. A new control strategy for the Knock Sensor system.
While the prior two strategies are integral to the change, it’s this third one that does much of the heavy-lifting.
Instead of only adjusting ignition timing (one stage) like on the original calibration, the new system involves three stages: The first stage upon knock detection is to adjust ignition timing.
If this doesn’t stop detonation/knock, it moves into the second stage employing a combination of ignition timing and increased fuel (as a percentage of fuel/air mixture).
If this doesn’t prevent knock, it triggers a third stage which further retards ignition timing and adds an even greater percentage of fuel.
If this third stage doesn’t prevent detonation/knock, then it goes into Limp Mode (7770 rpm limit and even more fuel).
I’m told by Ryan Hayes, Arctic Cat Engine Development/Calibration Engineer, that engines burning ethanol-blended, 91-octane fuel will likely operate in the first two stages. He also says owners won’t be able to detect any of these automatic processes, or the minor performance differences between stage one and three.
That’s only some of the good news.
Just as important, this new calibration strategy has been incorporated into all 2012 Arctic Cat 800 models.
I have been asked what the reflash was all about multiple times but never had been given any background on it, until now. Thanks for posting this useful info John.
All the more reason to use the nonoxygenated premium if you can get it.
Hey, I remember seeing that picture being taken out on a ride last season. Yep, witnessed the “OCTN” flashing first hand…. Marathon gas station here in New Prague supposedly has non-oxy premium…. John, have you picked up your new ride, yet?
Interesting. I had a 2010 F8 HO that I put 5000 miles on and never observed the “OCTN” flashing. A couple times I had to throw in some 87 octane just to get me to the next stop and did not see it. Being in southeastern MN was running ethanol gas also.
We will have to see how my 2012 800 runs ……
Chance of getting nonoxygenated fuel in MN: zero, zip, nada. We have two former Koch Refinery(now Flint Hills Resources) employees in our employ now. They don’t rinse out the truck before they deliver that supposed ‘non-oxy’ to the pump, you’re getting a mix of whatever was in there, crud and all.
Rick: The 2010 800 had an entirely different calibration, and there was no similar issue with them.
Hugh: That’s interesting, but not surprising.
The BP station in Albertville, MN has Non-Oxygenated gas. And they support sledders by buying a map ad from the local club!
Pennington Main and Pennington Square in Thief River Falls (home of Cat) as well as Eagle Square in Red Lake Falls have the nonoxygenated premium gas. I always try to fill up the machines before I trailer them anywhere. We even use it in all the lawn equipment at the farm. Might not be so easy to find when riding in the boonies though. Thanks for the info. I’ll keep it in mind if I run into any problems on my new 800.
Had my reflash done a couple weeks back. Despite using Kwik-Trip 91 octane that clearly states on the pump “Ethanol Free”, I was getting the “OCTN” message on the speedo. I’ll be curious to see what happens this winter. Maybe Kwik-Trips 91 octane really isn’t “Ethanol Free” as they say???
David,
I had a small-engine instructor give me one of these way back in 1989, a Briggs & Stratton brand but the same principle. When I feel like testing I buy 2 gallons, shake it and add to the tester. Kwik-Trip has their own transports so they may come up a little cleaner but they are still at the mercy of the previous load they had in there.
http://www.ebay.com/itm/ETHANOL-TESTER-ALCOHOL-TEST-E10-E15-E85-FUEL-GAS-GASOLINE-MALLORY-MARINE-9-79816-/150675416938?pt=Boat_Parts_Accessories_Gear&vxp=mtr&hash=item2314f4676a
http://www.smallenginesuppliers.com/shop/html/pages/products/Briggs_Stratton_Small_Engine_Tools35122.html
Hugh: Thanks for the links. Upon closer inspection of the Kwik-trip 91 octane pump, it states “No Ethanol Added”. Kind of leaves them open to the posibility of some ethanol being present.
Don’t get me started on ethanol…I’m glad I live in Wis. where premium w/o ethanol is widely available, and here in Oshkosh there are two independent stations that sell all grades of fuel ethanol-free.
The marine industry (and I suspect all powersports industry) has been fighting the move to E15. Here’s some recently testimony from a Mercury Marine engineer. Merc ran an E15 study for the EPA this summer: http://www.tradeonlytoday.com/home/517019-mercury-marine-engineer-testifies-about-e15-damage
whoever is claiming the 2010’s dont have the same problem couldnt be more wrong. we have nothing but poor quality ethanol fuel where i ride in maine, and my 2010 has had octane warning issues since day one.
I have a 2011 F8 EXT and I got the message until I started running Star Tron in my sled. Now, I am not saying that Star Tron was the fix, but I since I started running it I never had the message again. Also, I am not saying to not get the ECU fix, I just had mine re-flashed this past weekend. I will try it without Star Tron and see what happens, but if I start seeing messages I will start using it again. I think that stuff really works.
I´ve also had issues with the OCTN Warning on my 2010 M8.
I have also experienced the same problem on my 2010 Crossfire 8since day one… It is surely a pain in the ass!!! Is the flashing available for the 2010’s to??
Those guys at the factory sure know what they are doing, especially that Ryan Hayes guy !!
John, Why would the 2011 F800 be calibrated differently than the 2010 F8?
that was awsome. ive never heard such a good explanation on the web. ive got a problem 2010 m8 w can i willget 50 to 500feet then it dies like its outta fuel where should i start? please help
HI GUYS I HAVE A 2011 F-8 SNO PRO LEFT CYLINDER PISTON MELTED HOLE 700 MILES ON ODOMETER THEN CAT FIXED 760 MILES 2ND MELT DOWN NOW 2ND SEASON REFLASH DONE FIRST RIDE MAINE THIS WEEKEND OCTANE LIGHT CAME ON A LOT,RAN TANK DOWN LOW GOING TO TRY FUEL FROM SOUTHERN NH ,BUT WHAT GOOD IS THAT WHEN YOU RIDE NORTHERN MAINE YOU CANT ALWAYS FIND PREMIUM. ETHANOL SUCKS.
We have Non oxy gas in N.MN also…. my question would be since i have the flash done, and its supposedly changes timing and amounts of fuel/air mixtures, whats it gonna do when I put good gas like non oxy in? Is it gonna be a slugg from being richend out to far and timing retarded way down?stock
I had the re-flash done right when I got her. I bought it in october 2012 as a left over. So far I have not seen OCTN light. This weekend I was riding ODO only reads 380 miles and I saw OCTN flash. I shut it down and restarted it. No problems but how do I know for sure it is okay??/
I have a 2011 Arctic Cat M8 Sno Pro with the H.O. motor. I’ve been having some problems with it bogging out, I don’t know if it is fuel or what? Sometimes it runs fine then sometimes it boggs out. Does anybody know what the problem would be?
Thanks
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How do I know if mine has been reflashed. I’m having the octane light come on more often than not in northern MI where ethanol is supposedly a 10% blend and it sucks thanks for any info
Have a 2012 f8 octane code all the time .tried all different grades,brands ethanol free cam ll no change. Had the re flash done no better. Anyone have ideas because cat doesn’t wants me to measure squish band. I would think the squish if anything would be too big instead of undersized. Had the knock sensor re torqued and replaced. All temps and snow conditions. What is left?
Today 3/16/2015 I’ve had 19 Cats in my life time. This 2011 F 800 Sno Pro is the worst thing. Just came off a ZR 800 2003 and was scared to change to NEW stuff and my thoughts were & are correct yet. Dimond drive killed the next few yrs, & I didn’t want those. Now This thing has 1500 mi and after my second week on this used sled I can’t ride without seeing OCTN all the time. Timing has been put at 13 deg and no fix. Arctic Cat has lost it. Can’t buy product that works & don’t know what to do with this thing ?
Will try RE-flash if it wasen’t done. Was hopping after 3yrs the 4th yrs would have been fixed but 12’s / 13’s were a mess again. I only have a limited time for riding now to about 3 weekends now and this makes it hard to smile at / enjoy.
Hi everone! 2011 F800 SnoPro, Runs about 25% OF THE TIME IN OCTN ????? Timing retarded 2 Deg.FROM STOCK. And was reflashed Early that season. Brought to dealer THIS WEEK & was told ,didn’t know if Arctic Cat would Flash to correct problem! MY HANDS ARE TIED can’t jet up either! Hope to get it back this week for a last ride. Now I know why it had low miles when i bought it last spring 1,350 now 1,630.
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I have a 2011sp 800HO, been running great but now won’t start, anybody have problems with there not starting?
I have a 2011 cfr 800. in the shop as we speak getting 2 pistons because ‘the pistons have look like they have been running lean”
new pistons are in now and they tell me it seems to be randomly missing
Secondly I have one of the sleds that the low oil light is on because of the sensors malfunctioning. it only indicates low oil right ? it doesn’t put it in limp mode ?