858 help needed

[CB.8]

I got my 858 mc out for the first time this weekend. Put on 33 miles and now have 3.5 hours. The problem is it won’t rev above 6500 still. It did go to 8k 3 times for about 2 seconds each time. Changed plugs with no change. On the diagnostic screen I have 1mv on the tps and 3 mv on the exhaust servo voltage and they never change with throttle position.

Is there a chance someone with a MC could post a picture of the diagnostic screen while it is idling.

Thanks in advance.
Cb8.58

 

[Chad_Brochill]

I got my 858 mc out for the first time this weekend. Put on 33 miles and now have 3.5 hours. The problem is it won’t rev above 6500 still. It did go to 8k 3 times for about 2 seconds each time. Changed plugs with no change. On the diagnostic screen I have 1mv on the tps and 3 mv on the exhaust servo voltage and they never change with throttle position.

Is there a chance someone with a MC could post a picture of the diagnostic screen while it is idling.

Thanks in advance.
Cb8.58

Only thing I have seen floating around that might be an issue is the power valve cable is in a bind. People have had to bend the bracket that hold the cable to align it better. I am assuming you are asking because a Cat dealer is far from you?

There is also a service bulletin out there for the 858's below a certain VIN number that need updated ECU flashing. Chewy22 has a thread about it.

 

[CB.8]

Servo cable checks out. Mine is a late build and the I believe it falls into already flashed column.

I am in contact with the dealer, he is three hours away.

 

[Chad_Brochill]

Servo cable checks out. Mine is a late build and the I believe it falls into already flashed column.

I am in contact with the dealer, he is three hours away.

Man that stinks, hopefully its a simple fix on your end and you don't have to take it to the dealer. Kinda sounds like a power valve issue but these motors are so new its hard to know.

 

[tenacious84]

Is the exhaust valve servo cycling upon start-up?

 

[CB.8]

Is the exhaust valve servo cycling upon start-up?

It goes to the up position.

 

[tenacious84]

It goes to the up position.

A little more information would be helpful. Are you saying the servo is in the down position when the sled is off, start the sled and it goes to the up position and says there while the sled is running without returning to the down position while idling?

 

[CB.8]

It starts all the way down, goes to the up position, anthem goes down 1/4 inchish and stays there.

 

[zl5600]

I got my 858 mc out for the first time this weekend. Put on 33 miles and now have 3.5 hours. The problem is it won’t rev above 6500 still. It did go to 8k 3 times for about 2 seconds each time. Changed plugs with no change. On the diagnostic screen I have 1mv on the tps and 3 mv on the exhaust servo voltage and they never change with throttle position.

Is there a chance someone with a MC could post a picture of the diagnostic screen while it is idling.

Thanks in advance.
Cb8.58

Elevation? Are you clutched correctly?

 

[tenacious84]

It starts all the way down, goes to the up position, anthem goes down 1/4 inchish and stays there.

I was thinking of it from the perspective of my previous sleds and the servo used on the old 800 (up and down in reference to the actual valve instead of the servo). However, after taking a look at mine and seeing your comment it is easier to understand what you mean by up and down. The "up" position on the servo is actually the valve close position and the "down" position on the servo is the valve open position. So upon startup, it does appear to be operating properly. Mine does similar, but I didn't notice a 1/4 inchish down movement after the initial up.

 

[CB.8]

Elevation? Are you clutched correctly?

Stock clutching. Rode at 5500. Same response at home 2000 feet hung by tractor.

 

[CB.8]

I was thinking of it from the perspective of my previous sleds and the servo used on the old 800 (up and down in reference to the actual valve instead of the servo). However, after taking a look at mine and seeing your comment it is easier to understand what you mean by up and down. The "up" position on the servo is actually the valve close position and the "down" position on the servo is the valve open position. So upon startup, it does appear to be operating properly. Mine does similar, but I didn't notice a 1/4 inchish down movement after the initial up.

Usually goes down when you give initial throttle.

 

[tenacious84]

Stock clutching. Rode at 5500. Same response at home 2000 feet hung by tractor.

Usually goes down when you give initial throttle.

when hung by the tractor, does the servo ever go to the full down position or is the small down movement all the further it goes?

 

[CB.8]

when hung by the tractor, does the servo ever go to the full down position or is the small down movement all the further it goes?

Never goes down to full down position while powered. Fall when shut off. It appears according to the diagnostic screen that I have no voltage at the tps or exhaust servo.

 

[Old & slow]

Check all the electrical connections starting from the magneto. It's like an electrical plug isn't fully engaged.

 

[CB.8]

Update. Apparently the diagnostic screen is not report the correct information. It end Up being out of sync and out of spec power valves. Big thanks goes to Dustin and Outlaw Motorsports for getting me fixed up in one trip.

 

[tlunny]

CB.8,
Who did you buy the 858 from?
Was that calibration not part of pre-delivery? Just curious why it was out of calibration. Good on Outlaw for the find & fix, as your not a neighborhood kind of guy...

 

[CB.8]

I bought it from Outlaw. It is not part of the setup checklist from Cat. It seems to be a common issue across the board.

 

[tlunny]

Lovely. Lot's of moving parts requiring lots of details.
Glad they got a handle on it.
From an old timer, seems like things are in a funk whether it's a marketed sled or pre-order only. Reliability and calibration are the luck of the draw.
And for the current cost that's a travesty to me. And they wonder why I haven't updated. I be a dinosaur. Hope to be injector oil some day. At least I'll get some ride time! Hope the 858 runs like the wind Rob! Here's to a good snow year!