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P0301 Engine Misfire

38K views 15 replies 7 participants last post by  brnschr 
#1 ·
Hi everyone, I am having an issue that is getting really annoying and I am unable to locate the problem. I am really hoping someone in this community can help!! I have a 2015 Can Am Commander 1000 XTP. It currently has little over 16000KM of pretty much flawless miles and I love the machine. A little while ago upon starting my machine and idling to warm up, I heard a change in note and the engine was obviously running rough and on one cylinder. It went into limp mode and provided a engine misfire code P0301 indicating it was cylinder number 1. I initially just turned it off and upon restarting it worked fine and code was gone. Thought it was a one off... a week later same issue which was again resolved by just shutting off and restarting and the rest of the day was fine. It continued to do this and became a little worse over time doing it every cold startup and disappearing when engine was warm. I was preparing machine for a long trip and had dealer complete a few maintenance items including changing the spark plugs believing one may have been fouled a little causing the issue. The plugs with 15000km on them were in great shape and probably didn't need to be changed. The issue didn't happen at first at the dealer but before I took it they did finally see the issue and while hooked up to computer verified it was misfiring. They felt it might be a dirty injector and suggested I try some cleaner in my fuel. So I was beginning a 1200km 7 day trip and during same I used the best fuel I could find and did use a injector treatment (seafoam). The issue seemed a little better at first however it was still present. By the end of the trip however even with engine warm when I let it idle it would go into a misfire and limp mode. Re-starting still resets it and if I get on the gas I can still go all day!

So I decided its time to fix this for good... I tore everything down and first took out both injectors and the cylinder #1 injector did look a little dirty so I thought bingo... To be sure I cleaned them and swapped them so if issue was the injector it should now be cylinder 2. Nope still have problem and its still number 1. So Injectors crossed off list. Next thinking coil. I swapped out coil from identical commander (friends) and still no change. Swapped out coil wire to #1 still no change so not coil or wires. Had a fuel pump pressure gauge and checked pressure. Seems perfect with the pressure holding strong even when the engine dying down with misfire and not to mention issue never changed to any other cylinder except #1 so I am confident that fuel pump is ok. Next I am going to have a look at the air intake with throttle body etc as I did notice it was a little more dirty then I would like when I removed the injectors and could see behind towards the air filter. Thought about valve issues maybe but there is no sound and with the plugs being in great shape think they are ok?? After I try everything else I can I will get dealer to look valves over if necessary.

So question......... anyone out there have anything similar or any suggestions for me. Very annoying problem that needs to be resolved.

Thanks
Bruce
 
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#4 ·
I would think a misfire code would be an insufficient spark being delivered to cyl #1 .
How the computer determines this is beyond me but maybe excessive resistance ?
Not sure .
I would ( as stated above ) be pulling my plug wires , unscrewing the caps from the wires and nipping a bit off the ends .
Put a little dielectric grease on the freshly trimmed end and reinstall the boot and mini-zip ties .
 
#5 ·
Thanks for chiming in fellas, however as I explained in my long winded explanation I even swapped out known good plug wires caps and all to eliminate that issues. So it is not the coil spark plug wires fuel injectors or fuel pressure!

Any one out there with a suggestion?
 
#6 ·
I would check running compression... plus rpm drop of each cylinder as you remove a plug wire to see if their equal... you could have one broken ring, bad valve or a carbon build up in #1 cylinder or a slight vacuum leak at intake gasket(check intake gasket with a spray can of carb cleaner or ether ) at #1 cylinder ,as you mentioned its unlikely a spark issue,you changed all that and fuel pressure is good so it must be fuel air ratio at idle , you say once you get on it its fine...throw a vacuum gauge on it and be sure its steady, not jumpy...If its only at idle clean your Iac also...That's how I would approach it when its being a bi#ch...
 
#8 ·
When you say IAC you mean Idle Air Control? The commander doesn't have on it has iTC Intelligent Throttle Control which is basically Throttle accelerator(TAS) Electronic throttle actuator (ETA) and throttle position sensor (TPS) of which I am in the process of cleaning up inspecting.


Just removed the air intake manifold last night and the seal appeared ok with maybe a little dirt or leak on number 1 so fingers crossed that might be it. Will hopefully get it back together tonight for a test. I can see the valves with manifold removed and they definitely look a little scorched but that's with over 16000km so maybe normal wear?
 
#12 ·
So while I had the bike that far disassembled I continued and removed valve covers and adjusted them as well as took out the entire air manifold system and gave it a thorough cleaning. With closer inspection the air intake manifold at cylinder 1 did have a small leak as there was carbon and dirt built up on the cylinder intake and that side of manifold etc. It even got the fuel injector a little dirty as it was near the leak. (Wondered why that injector was dirty when I removed it earlier to test) Got most of it reassembled and will be firing it up tonight to see if my problem is resolved.

If it is I will let everyone know as it is a pain to go through so many potential issues to resolve this one! Thanks Hardly I believe you were on the right track when thinking about the vacuum leak and how it was at better at warmer temps etc... Next time as mentioned if someone wanted to check easily just have engine running and spray some carb cleaner around areas that may be leaking to see if engine ingests some!
 
#13 ·
Verdict is in!! It was a small annoying leak at the air manifold where it joins cylinder 1. The gasket looked ok and I didn't have a new one yet so I cleaned it thoroughly and then added a little gasket maker high temp stuff to ensure a good seal. I am ordering a new seal just in case but I suspect the fix will probably last a long time! Purrs like a kitten again.. 16000km and counting!

Thanks to anyone who chimed in and hopefully this will help someone else in the future to quickly diagnosis this issue.
 
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