coasting

[Hockey4mnhs]

i cant engine off coast b/c i have a auto. so lately ive been coasting down hills in N. Coast longer and go faster but i read a while back that some cars i think hodas shut off the injectors over a serton speed if there is not throtle applied. Is this really, if anyone knows please help

[omgwtfbyobbq]

If it's idling the injectors have to be on. What you're talking about only happens in gear. If the coolant is warm enough and rpm above some point (like 1500rpm) the injectors won't fire when you let off the gas and coast until the transmission gets to whatever the cutoff is (in this case 1500rpm), after which they start firing again. On some cars, they don't completely turn off, and will sporadically dump fuel into the catalytic converter to keep it's temperature up, but if you want to coast in N with the engine on, you should be o.k.

[Peakster]

Originally Posted by Hockey4mnhs

i cant engine off coast b/c i have a auto.

Can't you put the car in "N", shut off the engine, and then key start the engine when you're done the coast? That's what I was doing in the Silverado and Intrepid.

[Hot Georgia]

I shift to N in my '04 CVT HCH for about 7-10 miles of my 50 miles to work or back home. In the summer I switch to engine off coasting in those segments.

The reason I don't do the engine off in the winter is to prevent possible radiator stress for extreme, rapid heating/cooling expansion.

We also have a 2001 Grand Caravan which I'd love to roll in N. But I can not...the injectors stay on but when I need to go back to D the transition is very rough and jerky. Rev matching makes no difference.

[Hockey4mnhs]

isnt it bad in a auto to engine off coast because of sum bering not being lubricated? so thats y i leave the car on so it stays lubricated

[rh77]

Originally Posted by theclencher

Believe me- your radiator can take it.

I had to replace mine after some EOC-ing last summer in the Integra. It could've been due to the EO coasting and re-start, but who knows -- it had about 120K on it at the time.

Regarding the transmission, I'm told that it's not good to do EOC in a some automatics due to the lack of fluid pressure. For me that hasn't been confirmed. If you coast to a stop, it will shift down into 1st with the momentum, but the fluid should be present for lubrication. High-speed EOC for long periods could generate some heat, but I haven't heard of catastrophic failures as a result of this, first hand. Anyone???

RH77

[omgwtfbyobbq]

I don't think we would see an absolute melt down from EOCs since the output shaft bearing thingys aren't w/o lube for very long, but if you google you'll see reports of the output shaft being welded to the case after an RV owner decided to tow the wrong vehicle w/o unhooking the axles. The fluid's present, but at the bottom of the pan, so it's not much help to the output shaft about six inches above it. But.... There's still some fluid on after the engine's shut off, and it'll take some time to leave the bearings totally dry, but wear rates do likely increase, with the increase corresponding to the time the engine's off... It's a YMMV situation, and depends on the oil, tranny, and coast times/speed. I don't think the tranny will blow, but it may only last 200k miles instead of 350k miles, or whatnot.

[omgwtfbyobbq]

It almost seems to be a totally YMMV deal. Here's a discussion with plenty of googling material.

[rh77]

Originally Posted by omgwtfbyobbq

I don't think we would see an absolute melt down from EOCs since the output shaft bearing thingys aren't w/o lube for very long, but if you google you'll see reports of the output shaft being welded to the case after an RV owner decided to tow the wrong vehicle w/o unhooking the axles. The fluid's present, but at the bottom of the pan, so it's not much help to the output shaft about six inches above it. But.... There's still some fluid on after the engine's shut off, and it'll take some time to leave the bearings totally dry, but wear rates do likely increase, with the increase corresponding to the time the engine's off... It's a YMMV situation, and depends on the oil, tranny, and coast times/speed. I don't think the tranny will blow, but it may only last 200k miles instead of 350k miles, or whatnot.

My EOCs are closer to about 2-minutes or less to coast to a stop light and then after stopping for about a minute, re-start and go. There are times that shut-down on the Interstate occurs before an exit, and I can roll-up to a stop -- probably a bit more heat/friction, but you're probably right -- it may not blow up tomorrow (hopefully) but not run forever (350K). 220K seems like a decent amount of time, IMO, for an auto to last. I'm used to older domestics that give out at 110K.

My favorite story is when an RV owner went to tow their Toyota 4X4 and accidentally left the vehicle in 1st gear. 800 miles later, hmmm, it wouldn't start. Opening of the hood revealed thrown rods and real mess. I guess 65mph in 1st turns the engine at 11000 RPM+. Oops.

RH77

[Peakster]

Originally Posted by rh77

My favorite story is when an RV owner went to tow their Toyota 4X4 and accidentally left the vehicle in 1st gear. 800 miles later, hmmm, it wouldn't start. Opening of the hood revealed thrown rods and real mess. I guess 65mph in 1st turns the engine at 11000 RPM+. Oops.
RH77

I've heard a story of someone leaving the car in reverse. So when the car was towed forwards, the engine was going backwards! Can anyone say crushed valves?