Koop wrote:
Per my owner's manual, I always start my engine at low idle speed ~500rpm. After oil pressure is established - a few seconds at most - I use the idle speed control rocker switch to raise the idle in 25rpm increments to ~700rpm. Then I use the smart wheel cruise control to hit 1,000 rpm to build air pressure and warm the engine as quickly as possible. My Allison manual recommends 700 rpm input shaft speed, so once I've established that as my base idle, it remains there. On shut down I use the rocker to reduce to low idle again for the next start up.
Thanks for posting this. I had no idea that Allison even had a recommended rpm for input shaft speed. I'll look it up and set my base idle RPM accordingly.
I spoke to the cummins factory rep at Newmar today and he said that 1000 RPM for high idle is fine. So I think I'll leave the high idle there. Also, since the engine ramps up to 1000 RPM if I hit the high idle right away, I'm thinking that the computer probably checks oil pressure before ramping up. But I'll check that as well.
ON EDIT: I just looked up the low idle speed in the Allison 4000MH manual and it says it's between 500 and 800 RPM. Cummins recommended 650 which is exactly between the two so I think that's a good setting.
