Cold idle surge: TC40DA

pak7819 · Oct 18, 2011

Hello all. Noticed alot of great input from members on here and thought i would run this past the audience.

My 2006 TC40DA with 1100 hrs has a cold idle surge. It's apparent even when starting in say 60-70 degree weather, but worsens now that we're starting to see temps drop. It's kept inside, so it's not exposed, but wondering if anyone has any thoughts to the cause of this or had similar concerns on their own equipment. Located in WI so winter is coming... Will be kept in a "semi-heated" garage kept around 45-55 degrees during winter.

This is the shibaura 4 cyl engine offered by NH in the thier utility tractor glory days. Bought this outright from a local dealer that used it for a shop tractor until they decided to get aggressive on selling it. Anyhow, the fuel filter is clean, just recently changed, I have no tools to check rail pressure.

Tractor did this from the day I brought it home. Ran through the tank of fuel to empty, and then topped of with some fuel that i have to believe is higher sulphur content that what's avail today. I had a 55gal drum of off-road that I've been storing for some time. No change on running this older offroad fuel, surge didn't improve or get worse. Goes away after about 45 seconds or if you increase R's a bit while it's warming up. Once warm it purrs like a kitten.

Any thoughts? Jinamn? J J? Is this even a concern or something to be expected of a broken-in shibaura engine?

WM75Guy · Oct 18, 2011

My 2005 TC40DA with 500 hrs does not do that. The manual states to start at 1/4 to 1/3 throttle. I start mine at idle and then run it up a little to warm up. Mine runs on ULSD from Murphy/Walmart.

jinman · Oct 18, 2011

My TC45D will surge a bit if I leave the throttle at low idle. I always bump it up a tiny bit and don't worry about it. I believe it's caused by the governor before the engine oil comes up to temperature. The flyweights kinda over-compensate at low rpm when the engine is cold. As soon as the rpm or the engine temperatures normalize, the surging goes away. I wouldn't lose any sleep over it, but it is noticeable at low/cold rpm.

pak7819 · Oct 18, 2011

I re-read that section of the manual 3 or 4 times to find that comment to start at 1/4 to 1/3 throttle,...they sure hide it well. That will take care of it.

Thanks for pointing that out.

wolfpack2 · Oct 21, 2011

On my TC40D, it will do the samw thing if I start it with the throttle pulled too far back. Now I just throttle back to 1200 RPM before I shut it down. When I start it back up in the cold, there is no surging and it will start out at around 100 RPM below where I shut it down at. Within a couple of minutes, the RPMs climb back up to where I shut it down at. I don't like revving the engine when it is cold and I don't like the surge (can't be good for the engine). This solved my problem and lets the engine warm up at only a couple hundred RPMs above idle.