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E-VES cable causing low RPM in Axys chassis (at any mileage)

Murph

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There have been many threads on RPM fade/ low rpm on the Axys chassis both here and on other sites/ forums.

This cause/ effect was eluded to by SheetmetalFab in another thread but I wanted to start another thread in the hopes that it could help someone who was searching to find a solution sooner and easier.

The E-VES system has multiple components which translates to multiple possible points of failure. These components include:

ECU
PWM converter
E-VES Actuator
Relays
E-VES cable
wire harness
wire harness connections

Having a problem in any of these components can adversely affect performance-- typically manifested in peak rpm not being achieved. The service manual will lead you to believe that a code will be thrown for any E-VES malfunction offering quick diagnosis and solution. This is not the case.

A customer brought in a 2016 Turbo SKS with 2000 miles, complaining that the sled would only reach 7600 rpm. He mentioned that it had thrown a code (position not achieved) but that the code was not currently active. I elevated the rear of the sled and, after warming it up, opened the throttle to see what we could achieve rpm wise and whether or not it would throw a code. With no load, we could spin the motor up to 7600, no code thrown, and could watch the E-VES actuator move through the three positions.

When I removed the cable from the actuator, to do the service manual "push-pull" test for resistance and travel distance, the cable came out-- it was broken. This made me think about the E-VES system.

The system is set up where the ECU compares commanded position versus achieved position by comparing the hall effect sensor in the actuator versus voltage values at a given position. The problem with this system is that they are upstream of the actual exhaust valves and also the cable. Without a limiter switch on the actual exhaust valve or the tie-bar, there is no real way for the ECU to know if the intended valve position has been achieved.

There is a cable travel specification--full-in to full-out-- of 16-18mm.

If the cable has stretched, the exhaust valve may not fully open--leaving the exhaust port shrouded-- reducing peak rpm.

What can make this difficult to diagnose is that the ECU may not throw a code if the actuator hall effect sensor reaches it's intended position and the voltages correspond because they are upstream of the actual valves. This customer SKS did not throw a code and yet the cable was broken meaning the valves weren't opening at all.

How many Axys motors with low rpm issues have had the cable travel distance inspected? Are dealers doing this or are they simply using Digital Wrench to perform an E-VES re-learn without physically checking the travel distance?

I may add the cable to the list of components that I swap out at a specified interval (like motor rubber isolators) versus suffering cable stretch/ break performance issues.
 

mountainhorse

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Murph,

A couple of q's if you have the time...

Do you have the part number(s) for those cables?

What kind of cost each?

Can they be lubed?

How much of a PITA is it to change the cable?


Might be good for some people to have an extra in the trailer.
 

Murph

Polaris Moderator/ Polaris Ambassador/ Klim Amb.
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Lifetime Membership
Murph,

A couple of q's if you have the time...

Do you have the part number(s) for those cables?

What kind of cost each?

Can they be lubed?

How much of a PITA is it to change the cable?


Might be good for some people to have an extra in the trailer.

CABLE, EV VALVE, PUSH/PULL
7081870 $37 (Babbit's)

The cable could be lubed by removing the one end from the actuator arm.

To change cable, you need to remove E-VES assembly from cylinder. The problem lies in the fact that the service manual calls for a Digitial Wrench relearn after replacing the cable. When I receive the cable, for the previously mentioned customer SKS, I am going to see if it is possible to measure and replicate the cable attachment on the tie bar and see if it can be replaced without the relearn procedure.

Unfortunately, I have not found a way to manually enter a relearn code through a series of control inputs-- similar to how you can manually prime the oil pump without Digital Wrench.

My question is whether or not a BullyDog GT would have the capability to perform the E-VES re-learn?
 
C
Nov 26, 2007
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So is this cable like a throttle cable, bike shifter cable, etc? I haven't really looked at mine yet. When the EV get gummed up, is it too much resistance for the cable so it stretches? Can you prestrech the cables like on a bicycle? Would cleaning EV more often, help prevent this?
 

richracer1

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I got some pictures of my spare exhaust valves.

This the underside of the valves


The nut to the right is what you loosen to remove the outer housing - there is no adjustment to this, loosen enough to remove the housing and tighten snug when putting it back together. The nut inside the housing is fixed.


This is the nut that must be removed to R&R the cable. After looking a little closer to the shaft this nut screws onto, it doesn't look like there's any kind of adjustment. The back side looks to be another fixed nut, so you would just tighten this nut down snug.




The actuator end. The nut to the left is not adjustable, the nut to the right just holds the cable to the actuator bracket.
 
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richracer1

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FWIW, I installed a completely new exhaust valve setup when I did the BMP 860 mod last summer. As peace of mind, I had the dealer do the relearn, everything was within spec. Everything but the outer housing comes assembled from Polaris when you buy the kit.
 

Murph

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FWIW, I installed a completely new exhaust valve setup when I did the BMP 860 mod last summer. As peace of mind, I had the dealer do the relearn, everything was within spec. Everything but the outer housing comes assembled from Polaris when you buy the kit.

Rich,

I'm curious what you mean by the bold statement, when you perform a E-VES relearn in Digital Wrench it goes through the procedure of opening and closing valves while turning the MFD on and off-- it never states any values or otherwise notifies the operator of any changes. It basically just says when it is finished.

You have a BullyDog GT on your BMP 860, correct? Does the BullyDog give you the ability to observe E-VES funtions or perform the re-learn?

Thanks,
Murph
 

richracer1

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Rich,

I'm curious what you mean by the bold statement, when you perform a E-VES relearn in Digital Wrench it goes through the procedure of opening and closing valves while turning the MFD on and off-- it never states any values or otherwise notifies the operator of any changes. It basically just says when it is finished.

You have a BullyDog GT on your BMP 860, correct? Does the BullyDog give you the ability to observe E-VES funtions or perform the re-learn?

Thanks,
Murph

No the Bully Dog does not do that. The technician's exact words were, "everything is in spec, were you having running issue?". Sled has been pull & go all season.
 
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Wheel House Motorsports

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Because of how the motor and system does its function check you could litterally unhook the cable and it would never fail the relearn or throw a code, just run like trash. Im curious for the guys having low RPM issues a guy could easily unhook a cable, ziptie it so it was held fully open and run. Obviously bottom end would suck. If RPM was restored it would seem the cable and proper travel are the culprit. Or one of many. lol
 
O
Dec 9, 2014
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Because of how the motor and system does its function check you could litterally unhook the cable and it would never fail the relearn or throw a code, just run like trash. Im curious for the guys having low RPM issues a guy could easily unhook a cable, ziptie it so it was held fully open and run. Obviously bottom end would suck. If RPM was restored it would seem the cable and proper travel are the culprit. Or one of many. lol

I have the exact same thought, why doesnt Polaris do this test as one of the first things to look at? Just to locate the problem and at the very least be able to eliminate other things.
 

HECKS

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So to be clear, to check the cable I can just remove the eyelet from the actuator and do a pull test and measure it's distance of travel ?
 

Murph

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So to be clear, to check the cable I can just remove the eyelet from the actuator and do a pull test and measure it's distance of travel ?

Correct.

Although you first need to push cable in (the rest position is the middle position for easier starting)

Pull out slightly (8-9mm) you will feel middle position

Pull out rest of way (8-9mm) and you will feel full up position

Action should be pretty smooth

It was during this test that I had a cable come all the way out that was broken.
 
W
Mar 16, 2011
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broken bolt on tiebar- TWICE

FWIW, after chasing RPM fade for 2 months last year... belt, clutching, motor mounts, SLP torque arm... I learned (another) valuable lesson in overlooking the obvious. I took her out for the pre-season and to install all the new stuff ^^ mentioned. Still taching 76-7800. Pissed. Exhaust valves FELT good by manually moving the actuator. In desperation, I pulled them for a cleaning even though I suspected they wouldn't need it- and they didn't. However, removing the housing that covers the tie bar/valve assembly revealed that the bolt holding the PTO side valve to the tie bar had sheared. I heated it damn hot in the vise and was able to extract it. bam. Ran like a raped ape, until today. Sheared another bolt. And no, I did not over torque the replacement. same bolt, same side, same symptoms. I sure chased down every other problem in the world- and spent a bucket of cash- because I didn't check the obvious first. My .02:face-icon-small-coo
 
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