I'm having an issue that started when the new style coolant pump went on my 2014 Limited. The new style pump constantly circulates coolant through the heads and radiators, unlike the old style that would close the heads off from the radiators into two separate circuits using a thermostat at lower temperatures. This isn't an issue on the M8 engines because from what I understand, the pump can cycle on and off as needed. On the Rushmore Twin Cams, the bike only uses two of the four pump electrical connections and runs any time the engine is running.
I asked something along these lines during the summer but mostly got off topic replies. At the time I was having trouble getting the engine to heat up enough to get a good autotune session on the FP3. The good folks at V&H helped me through that issue by lowering the session starting temperature.

Now that the weather is cooler I'm running into a new problem. When it's cold out (seems like below 18°F or so) the engine stays in high idle and won't come down to idle speeds regardless of how long I sit at a light. I pull out of the garage (about 68° ambient) and start the bike, if I were to sit long enough it will idle down after a few minutes because the block is somewhat warm, but as soon as I take off the engine cools below whatever threshold temp the ECM deems necessary to idle back up.

I tried covering part of the honeycomb covers on the lowers to reduce airflow to the radiators during the summer with little success. Not wanting to risk damaging anything I stopped at reducing 50% of the cooled area with duct tape.

I'm considering trying to work the stock bypass thermostat into the new pump's tubing or trying to temporarily block more of the cooled surface on the radiators.
Does anyone here have any experience with this issue? High idle isn't the end of the world, but it does make the ride less enjoyable for me and I would rather the engine be able to hold a better working temperature for longevity.

 

As I understand it the newer M8 cooling system (and the upgraded pumps) the pump runs continuously and the fans cycle on and off depending on what the ECM sees from the head temperature. might want to see if your cooling fans may be running and not shut off, could be a bad temp sensor or maybe not.

I am sure someone who knows more will be along to help.

 

There is a table in the FP3 that allows adjustments to the idle speed at various engine temperatures. Get ahold of V&H, tell the what you’re telling us and have them adjust your map.

 

The fans only come on when the heads reach the max temp (I 'think' its 335°) Coolant temp sensor and head temp sensor have been replaced with no changes.

 

Thank you for the response.
I'm really looking to raise the actual running temperature of the engine, I could make the engine idle at a lower temp but that's not really fixing the issue. V&H's response to the low temp issue during the summer was that the engine needs to attain certain temperatures to work properly. I think the reason is for all the parts to expand and fit together as designed as the engine is running, as well as for the lubricants to be the correct viscosity to do what they do.

 

When you changed to the newer pump did you have HD update the ECM for it? I have the newer pump on my 2014 and I do not have the issue your having.

 

I’m not aware of any ECM update for the water pump upgrade. I just called the dealer and they aren’t either. Also reread the instructions and no mention of one there.

 

I've never had those issues with the new style pump and FP3 on my '15 Ltd.

Your engine will run fine with no coolant flowing. Many riders have posted here (myself included) about riding with a failed pump with no issue. I think you could obstruct the airflow through the rads, disconnect the fans, or do both while you sort through your issue.

 

One other thought: I expect you bled the system of air per the instructions, it might be worthwhile to check the reservoir for the amount of coolant and lines for air. Do not know if that would make any difference in operating temp though.

 

Thanks for the input! The cooling system has been checked and is properly bled, working properly. The fans don’t come on unless it’s close to 100° ambient and the heads reach somewhere around 330°. For the heads to reach those temps I have to let the bike idle for an extended time after running it hard.
I covered the grills for now but it’s warmed up a bit (60’s today) so I’ll test more when it gets colder again.