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Mine does the same thing, 3ri tune full exh and KWI clutching, I think it's in the clutch, trying to shift up or down at that speed, go a little faster and it shifts.. slow down and it doesn't do it.
 

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Having similar issues and belt change only helps a little. Does it on both stock and Dynajet mild tune. It did not do this a few hundred miles ago.
 

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Is it only in sport mode? I’m thinking it might be when the throttle is more sensitive in sport mode. Like is it better in eco mode?

I’m wondering if your foot is bouncing on the gas pedal in the more sensitive sport mode….
 

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Mine was doing the same thing. Ended up being a bent rear axle. Thought it was a tuning issue as well because it would only do it at cruising speed. At full throttle it wouldn't do it at all. Which you would think would be worse with more stress on it. Hope this helps good luck
 

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Is it only in sport mode? I’m thinking it might be when the throttle is more sensitive in sport mode. Like is it better in eco mode?

I’m wondering if your foot is bouncing on the gas pedal in the more sensitive sport mode….

I thought about that. Happens in both mode's.
 

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Having similar issues and belt change only helps a little. Does it on both stock and Dynajet mild tune. It did not do this a few hundred miles ago.
Check for bent axle or driveshaft, takes very little of a bend to be able to feel it. Next i would inspect clutches very well.

Sent from my SM-G981W using Tapatalk
 

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Mostly I don't know what's going on with the engine controller and clutches. Plus I didn't understand what was meant by smoother shifting as advertised by KWI. That said, after having the full KWI job done (maintenance, machining sheaves and floating secondary) at first I felt like I lost some power. This is because at full throttle my speed increases smoothly all the to top speed. I don't think it's slower after all but just smoother. In other words I seem to have lost those hot spots (stronger acceleration) during the speed ramp. I'm thinking this might be what they meant by smoother shifting. The clutch dynamics remain a mystery to me but I'm thinking your surging might be related to the clutches. Might. be worth a conversation with Airdam or KWI. Good luck!
 

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Might check the bushings in the secondary, It was explained to me when I was having some similar symptoms that the bushing on the sliding sheave in the secondary may be getting worn, and as it is loaded it may be binding instead of sliding until a decrease or increase in torque which would allow it to unbind.

After having the bushing replaced my car performed much better.

this could be completely unrelated, and or my understanding is just batshit crazy.
 

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Not saying some of you guys may not have mechanical issue's but there is another thing that causes surges to in the stock and aftermarket ecm calibrations. So it's possible some of you guys may be chasing an unfixable problem. The condition I describe below is most noticed in steady state cruise conditions at light load 20-50 mph roughly. These machines use load based timing, when the actual engine load surpasses commanded it retards the timing, afr's go way rich to combat the increase exhaust egts from the retarded timing to protect that cat and turbo. When the desired load is above the actual engine load the timing goes back to normal, cycle repeats. This could be the surge some may be refereing to, I've data logged 100's of hrs trying to figure this out. The turbo is on the small side for great throttle respone and driveabiltity. There are some down sides to this: the turbo is making a decent amount of boost at part throttle conditions so it causes a runaway condition that's were the retarded timing comes in to decrease engine load. Next time you cruise down a long stretch off road at a steady state 30-45mph stop and get out to look at the turbo it will likely be glowing from the reatrded timing.Then go do some wot passes up/down the road or track and get out and look there should be no turbo glow. The ecm will be using more efficient spark timing values putting the heat back into the engine/cooling system vs the exhaust at high load conditions.
 

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I often wonder why I even waist my breath here. Every X3 does this, some can feel it and others well yeah I will keep my comments to mself.
Red line is left/blue is right: 1. The verticle line shows were it starts, on the bottom you will see the actual load surpass the load target, 2. top chart you will see the timing take a steep dive (retarded), 3 middle chart AFR`s go way rich. Now I don`t know about you guys but I can feel this and it pisses me off. I hated it so bad I tuned it out and deal with the over boost runaway problem at part throttle.
270430
 

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Here is another view showing were the calculated EGT surpasses 1670 F and it richens the AFR's. Hopefully this helps some of you, honestly I'm just here trying to help some to be aware of this. A guy can spend a lot of money chasing a issue he can't fix. Open the images in a new tab for better view if needed.
270433
270434
 

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Not saying your wrong and I do appreciate your input however If this was true in my case then why out of the blue did start. Before then there was no issue with the way it ran.
 

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It's only noticeable in very particular riding conditions, I don't notice it in any conditions were there is a lot of throttle management. Such as the dunes, winedy trails ect. I notice it the most riding long trails/roads with steady speeds 25-45mph were it requires small throttle changes to maintain speed. Also notice it on small inclines/declines at steady speeds. Another thing that seems to make it worse is in the summer were temps are 85-100+. Driving conditions that the pedal is used like a light switch I never notice it.
 

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Just to clarify what mine is doing. It's not a large surge as it is more like a change in engine pitch between 19 and 26 MPH. Past that it starts to diminish and increases in pitch rate until you get into the throttle. It feels like the X3 is running on a bad belt except its a new one. How did you tune it out?
 

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I eliminated most of the retarded timing when the actual load passes the desired load. The ECM uses it to decrease engine load so you will still need it in some places such as the idle areas. It also causes a spot in the throttle at light load were backing out of the throttle gets to a point were it doesn't really decrease load until you let off the pedal all the way. From what I can see in the logs the throttle actuator gets to a point were it does not keep closing for a linear throttle actuation, it has a low stop point. It does finaly close all the way when the throttle is released, this is the runaway condition I mentioned and so far the only fix I've found for it is a compromize of bringing a little timing retard back in on those areas. So at part throttle the turbo is building boost stuffing air past that partialy open throttle body. It can cause a light switch feel and can being annoying, I would take this over the normal cruise surge especially for the big gain in mileage in cruising areas to. It no longer cruising down the long strechtes of road at 10.5 AFR and 10-12 degrees of timing. Get a dynojet display if you don't have one and watch the timing and requested AFR you will be like WTF? If you decide to mess with any of it definately get the wideband setup to.
 

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My Dynojet always tells me the requested AFR is 14.7. I am using their canned tune currently. I would have to load the stock tune to make any programming tune changes.
 

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My Dynojet always tells me the requested AFR is 14.7. I am using their canned tune currently. I would have to load the stock tune to make any programming tune changes.
If it's always, it's just reading the wrong value then, 14.7 is stoich and around what idle AFR is. You'll drop into the 10/11s under high load. The X3 runs way rich, but it helps w piston cooling and fuel economy isn't really a thing most care about in this application.

I don't have the surging on my rig, but most off the shelf tunes gain most of their 'power' by making the throttle touchier, so things come on faster and earlier in the peddle %. Ultimately this just makes the peddle less usable and makes it harder to modulate the throttle, and makes it feel surgier. Sure they add some power under the curve also, but that's not most of what you're feeling.

@rcr1978
Calculated EGT sensors aren't overly accurate either, they use the O2 sensor to guess how much fuel was burnt and what the temp might be. If you remove your cat, this number is completely bogus. If you are actually hitting the component protect (1670F) and it's doing things you're feeling/annoyed with, you might have your cat delete to blame. You might as well bump that limit. Removing intake and exhaust restrictions will also cause you to overshoot your load (😂), same with having the wastegate crack pressure too high.

It's somewhat insane how modern day ECUs can protect us from ourselves and keep the car running properly in light of so many changes/problems. 25 years ago we'd all be blowing turboed motors left and right making flow changes.
 

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The pics of the datalog I posted up was a stock tune, it even did it with the cat in place. The dynojet tunes bump there's up to 1905F roughly and it will still hit it easily when the load overshoots the desired load=cruising. It helps bumping the EGT threshold up but that's not the fix all. Getting rid of the rediciulous timing retard fixes the high calcuated egt's.
 
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