Belt blown now limp mode

EtOH said:

Hello,

I've run across a strange problem recently. My belt exploded which I figured would happen at some point so I got a new one and changed it out but now My x3 goes into limp mode if I try and maintain a steady speed. If I'm going slow its fine or if I'm driving it like I stole it is fine but as soon as you try and just drive like your commuting it goes into limp mode and I've gotten a code P2279 along with the P0301 - 3 I know theses are misfire codes but are random and it does not start to miss fire until the P2279 pops up at which point limp mode is active. Any Ideas? Thanks.

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That's very odd. My guess is it's unrelated to the belt and just a coincidence. I would troubleshoot the code for things that cause a misfire. I've never done a belt change in one of these, but it's there any chance you bumped a sensor, pinched a wire, or have something shorted from the belt change?

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It was very odd to me as well, I forgot to mention that if I just restart the engine everything is cleared and wont have the problem again until the same scenario has played out, so I can literally shut it off restart it and go 0-full speed with no issues but as soon as you try to cruse at any kind of constant speed it pops back up.

Could be the engine knock sensor "hearing" excessive noise from the clutches after your belt mishap and throwing the misfire code, thinking the noise is engine related.

When your at low speed, the noise isn't loud enough. When at WOT the clutches are highly loaded and more quiet than at grocery.getting cruise mode when the noise is it's loudest.

Welcome...and since your new here, there are many threads and posts regarding this, so spend some time and Search them out for a better understanding.

I had a similar issue once, it kept throwing misfire codes once the rpms got up there and going into limp mode. After trying lots of things, and clearing codes with my map tuner the belt finally broke and I realized it was the Belt the whole time. Apparently the belt must have partially come apart and some cords got wrapped up in secondary, preventing it from shifting out. Threw a new belt in and all was good. However when I got home and inspected further I noticed a roller broke in half. When I was replacing that roller another one broke in half and fell out! This may not be your problem but others might find this post useful and check belt and rollers first before tearing intercooler out and checking plugs, etc.

EtOH said:

Hello,

I've run across a strange problem recently. My belt exploded which I figured would happen at some point so I got a new one and changed it out but now My x3 goes into limp mode if I try and maintain a steady speed. If I'm going slow its fine or if I'm driving it like I stole it is fine but as soon as you try and just drive like your commuting it goes into limp mode and I've gotten a code P2279 along with the P0301 - 3 I know theses are misfire codes but are random and it does not start to miss fire until the P2279 pops up at which point limp mode is active. Any Ideas? Thanks.

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Do you have a tune ? My car acted exactly like that because at mild cruise, it was so lean that it would misfire. After a bit, the ecm would shut down the cylinder that was missing. The tune has been revised, and is no longer an issue.

Well I must ask whose tune and what stage tune was the culprit.

Belt slipping or issues from what I know can also cause them to throw a misfire code. Take apart and make sure you actually got all the cords and stuff out of the clutches from the belt break.


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90% sure you still have left over belt somewhere in your clutches


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That's what I'm thinking there's some cord wrapped in there somewhere.

Just for a thought have you checked you pre-filter and air filter?

This is exactly what my machine is doing, did you ever solve this at all, I have a different code but I get the p301-303 codes and limp home mode but after I shut it off it’s fine until the same thing again, same exact scenario happens to me.

Anthony, that guy hasn’t been here in 5 years.

Dr. Dirty said:

Anthony, that guy hasn’t been here in 5 years.

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Ehh worth a shot haha. Maybe just maybe he’d respond

Be sure ALL belt debris has been removed from both clutches. Cycle both clutches and blow them out and inspect for left overs. Put on an OEM or WBB belt and try it. You likely are seeing belt slip causing the misfire codes.

some models were sent out with the misfire settings too aggressive
brp has a tune update for some model years
if your car can be tuned, most tunes have the misfire detection turned off
we use to be able to turn it off with the pv3, but dynojet has locked the tuning for consumers

jknapier said:

Be sure ALL belt debris has been removed from both clutches. Cycle both clutches and blow them out and inspect for left overs. Put on an OEM or WBB belt and try it. You likely are seeing belt slip causing the misfire codes.

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I've seen this repeated on this forum, but I don't buy it. It's not like there is a belt slip sensor and if there were, why not throw a code for it instead of the misfire on a specific cylinder. Other than speedometer, what else would compare wheel or final drive rpm and determine belt slipping. Some slipping is expected in normal CVT operation. I've asked about this before but no one has come up with an answer.

the misfire detection is a guess from the ecu based on crank speed and sound
so very fast rpm changes keeps the ecu guessing
so the motor revs fast on slip and then when the belt grabs the rpms fall fast
the ecu see the sudden drop with no pedal change and ecu assumes it is from a misfire

I think its based on a hysteresis on the rpm sensor

I was thinking it could be a knock sensor picking it up.