Not sure where to post this but here it goes. Hope I don't sound like an idiot lol but I just bought an lml and was cruising down a big hill in Idaho so I put it in neutral but the rpm was still 2000 like there is a drag, isn't it supposed to go down to idle speed?
RPM high in neutral
- Thread starter pavetim
- Start date
As others have said don't do that ever again.
No, it doesn't save fuel, in fact it actually uses extra fuel. Truck is designed to be left in drive and let the engine and transmission work together to slow the truck and trailer down. The truck idles at that speed in anticipation of you shifting back into drive so the transmission isn't damaged. The only time these trucks don't work properly is when the operators try to outthink them, these trucks are smart and know how to slow the load down, i.e. Grade braking and engine braking, without input from you.
No, it doesn't save fuel, in fact it actually uses extra fuel. Truck is designed to be left in drive and let the engine and transmission work together to slow the truck and trailer down. The truck idles at that speed in anticipation of you shifting back into drive so the transmission isn't damaged. The only time these trucks don't work properly is when the operators try to outthink them, these trucks are smart and know how to slow the load down, i.e. Grade braking and engine braking, without input from you.
Dfco, decel fuel cut off. If going downhill, leave it in gear, the engine will go into dfco mode if it's coasting, and use the engine to help maintain your speed going downhill. Surprised your post wasn't asking about a loud pop going into nuetral from the c5's coming on and the rotating assembly spinning up rapidly. I know if I go to nuetral at slightly to fast a speed to shift into 4 low, I get the clunk from the c5's engaging in nuetral(did this one time slowing down while still in 2nd getting ready to shift to 4low, won't do that again).
I shifted mine into reverse once cruising down the highway. A ****ing wasp popped out of nowhere on me and I hit the shifter trying to slap the wasp out of my face. R blinked and I shifted back to Drive and went on about my trip. I knew the trans wouldn shift into R at speed, but also didn't notice any clunks or weird engagement back into drive. 75mph.
When my trans was stock, I would slap it in R all the time at 70 MPH to dick with tailgaters (backup lights come on). Never hurt anything. I would let it go into neutral as well, and never had any noises or issues.
My first built trans tied up in neutral at 35 MPH, locked up the rear tires. It was fine for a second, then the C5 must have come on before whatever clutch let off, because BANG! and the rear tires stopped dead... Current built trans handles it better, just a thunk but no jolt the one time I hit neutral by mistake. So don't go to neutral on a built trans, they don't handle it well.
If you are stock, do what you want, GM will fix it :spit:. I've never personally seen a stock trans have a problem going to neutral while moving, but your mileage may vary.
My first built trans tied up in neutral at 35 MPH, locked up the rear tires. It was fine for a second, then the C5 must have come on before whatever clutch let off, because BANG! and the rear tires stopped dead... Current built trans handles it better, just a thunk but no jolt the one time I hit neutral by mistake. So don't go to neutral on a built trans, they don't handle it well.
If you are stock, do what you want, GM will fix it :spit:. I've never personally seen a stock trans have a problem going to neutral while moving, but your mileage may vary.
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Gas motors do the same thing, have for decades. If your vehicle was made this century, you don't want to put it in neutral to save fuel. They all have DFCO. Even with a manual transmission, you are better off leaving it in gear and just letting it coast.
If your that worried about fuel, buy a Prius, why would you go to neutral rolling down a long grade, so you can burn the brakes up too?
All new engines hold rpm at speed in neutral, even standards do it, I'm guessing to keep line pressure up and reduce damage when you put them back in gear, also the clutches are still allowed like stated so it idles up for those reasons as well.
All new engines hold rpm at speed in neutral, even standards do it, I'm guessing to keep line pressure up and reduce damage when you put them back in gear, also the clutches are still allowed like stated so it idles up for those reasons as well.