850 TPS

[Teth-Air]

Has anyone dove in and looked closely at the new TPS? I find my 850 is fat on the bottom end and from dyno testing I have seen it was confirmed that leaning out this motor has increased HP.

I am not ready to chance my motor yet but if the throttle bodies do have an adjustment screw to set them compared to the TPS I wonder if a guy could adjust to the lean end of the spec. in order to make these motors run better?

Maybe the butterflies are fixed compared to the TPS?

Other ways of leaning out the motor? Sensor manipulation? temperature or air pressure?

Anyone do this on other motors with success? that would relate to this motor?

 

[m1kflyingtiger]

Has anyone dove in and looked closely at the new TPS? I find my 850 is fat on the bottom end and from dyno testing I have seen it was confirmed that leaning out this motor has increased HP.

I am not ready to chance my motor yet but if the throttle bodies do have an adjustment screw to set them compared to the TPS I wonder if a guy could adjust to the lean end of the spec. in order to make these motors run better?

Maybe the butterflies are fixed compared to the TPS?

Other ways of leaning out the motor? Sensor manipulation? temperature or air pressure?

Anyone do this on other motors with success? that would relate to this motor?

I know the older m-series cats you could put an adjustable fuel pressure regulator on them and trim the whole map up a bit by just turning that down. Was almost a nessecity as their fuel pressure was all over the board from the factory.

 

[Teth-Air]

The 850 has a fuel pressure sensor so would likely blow a code by turning the pressure down.

 

[m1kflyingtiger]

Where is the sensor located?

 

[TRS]

The 850 has a fuel pressure sensor so would likely blow a code by turning the pressure down.

Yep

 

[Teth-Air]

Where is the sensor located?

Not sure yet, only read about it.

 

[tdbaugha]

Altering the fuel pressure circuit won't work. If you "increase" fuel pressure to lean it out, the max fuel it will pull is 1.5% and alternatively if "decrease" pressure below 43psi it will throw a code.

 

[Teth-Air]

Altering the fuel pressure circuit won't work. If you "increase" fuel pressure to lean it out, the max fuel it will pull is 1.5% and alternatively if "decrease" pressure below 43psi it will throw a code.

So you know a bit about this new motor it seems. Any idea on how much influence the exhaust temperature sensors have on the map? Wondering if I could manipulate them a bit. I assume they are just resistive sensors?

 

[tdbaugha]

Sorry, I don’t know anything about the two temp sensors. I’m assuming they built the code similarly to the fuel pressure I mentioned. They don’t want the ECU easily tricked so that people can run aftermarket parts without them knowing it.

 

[m1kflyingtiger]

Altering the fuel pressure circuit won't work. If you "increase" fuel pressure to lean it out, the max fuel it will pull is 1.5% and alternatively if "decrease" pressure below 43psi it will throw a code.

What pressure does it normally run at? If normal is 46 and it doesn’t throw a code till 43 we could lean it to 43.3 and have a little gain. I know those old m sleds 1 or 1 psi was a big difference.

 

[Teth-Air]

Anybody have a shop manual yet?

 

[Teth-Air]

So I just installed a primary spring with start rate of 145lbs. Stock is 120. I was hoping to clutch just above the fat crap but I don't think I will like it as it has made the sled feel jerky on engagement. Any other safe ideas to start with?

 

[kanedog]

So I just installed a primary spring with start rate of 145lbs. Stock is 120. I was hoping to clutch just above the fat crap but I don't think I will like it as it has made the sled feel jerky on engagement. Any other safe ideas to start with?

Try a lighter spring and lighter weights.
Example stock-66gram, 120/310
Try 62gram, 100/267 polaris gold, 7041148. The ratio is about 1g=100rpm.
This may free up the motor down low as there won't be as much clutch weight to swing around.
Same effect, same belt clamp force.

Sent from my SM-G920W8 using Tapatalk

 

[Teth-Air]

Try a lighter spring and lighter weights.
Example stock-66gram, 120/310
Try 62gram, 100/267 polaris gold, 7041148. The ratio is about 1g=100rpm.
This may free up the motor down low as there won't be as much clutch weight to swing around.
Same effect, same belt clamp force.

Sent from my SM-G920W8 using Tapatalk

Makes perfect sense as my 800's never felt jerky with lighter weights. And clutch lasts much longer. I was trying to go cheap with just spring change. Now need to buy weights.

 

[tdbaugha]

What pressure does it normally run at? If normal is 46 and it doesn’t throw a code till 43 we could lean it to 43.3 and have a little gain. I know those old m sleds 1 or 1 psi was a big difference.

You can’t lean it out by dropping the actual pressure. The sensor reads it and adjusts fuel accordingly. If you modify the sensor signal to make it think there’s less pressure, you’ll be increasing fueling and making it more rich.

 

[m1kflyingtiger]

You can’t lean it out by dropping the actual pressure. The sensor reads it and adjusts fuel accordingly. If you modify the sensor signal to make it think there’s less pressure, you’ll be increasing fueling and making it more rich.

Makes sense