When im like going 40-50 60mph and i put it in nutrual he rpms go up and down like 800 to 500.. and i was wondering why? My tire size is 275/75/17Im guessing thats orginall size tires. was just wondering whats throwing my rpm's like that.. Thanks guys

Why are you doing this. ????
Your engine has to rev higher to engage the torque converter, At high way speeds your going to F up your transmisson, the fly wheal, torque converter, fluid have to adjust to the speed of the drive shaft and rear diff.

Don't do this ,...

wow.....ya dont do that...especially at those speeds.. bad move dude. like cyclone said its engaging the torque converter and dont ever throw it into nuetral at that speed unless your looking to get a new tranny soon ahah

dam wow, thanks never know that.. So say im rolling to work at 65mph and going down a hill dont put it in N? dam thanks guys im glad i asked as soon as i did.. I just got the truck its a 05 1500 4.7 5speed long bed single cab.. Maybe i forgot a little detail.. its a 5 speed.. Im shore if you guys thought i had a automatic or not.. sorry

even so, don't do it a maunal, its harder on the clutch, throw out bearing, presaure plate, The same concept apllies to a automtic, the engine has to increase rpm to match the drive shaft, rear axels, I have a 6sp manul in my hemi, and I don't coast at high way speed, its one thing to know you going to coast to a stop at a red light and start over, but on the high way, your wasting flue and any free mileage you may think your getting is not worth the abuse.

I actually was gonna make a post similar to this, except I AM NOT putting my truck in neutral at 45-60mph. I have a 4.7L Magnum auto V8 in my 2005 Dodoge Ram 1500, and I've been having the commonly discussed rough idling problem when I come to stop lights, complete stops, etc, and until I find out what the problem is, I've been putting the truck into neutral when approaching stopping points, ie, at or below 10mph while my truck is gearing down preparing to stop but before it starts the rough idle and stalling problem. I wanted to know if I was potentially presenting a potential for new or further damage by doing so or if this was okay at this level. Any suggestions and advice welcome. Thanks in advance!

You get worse mileage by shifting to neutral while going downhill than you would by leaving it in gear and letting it coast. Why? In neutral, it's got to fire the injectors to keep the engine idling. Coasting in gear, it completely kills the injectors, meaning you use NO fuel during that time. It doesn't get any better than that.

Other than that, erratic idle can be either a dirty throttle body (clean it) or idle air control motor (or whatever the appropriate term used for Dodges).

I've been driving standards for almost 20 years and this is the first I've ever heard of coasting being bad for the engine or tranny.

John M if it killed the injectors, there's no fuel getting to the engine meaning it would stall wouldn't it?

[quote]ORIGINAL: kregier

I've been driving standards for almost 20 years and this is the first I've ever heard of coasting being bad for the engine or tranny.



If your coasting and going back into gear, at the same speed as you would when up shifting, than your not going to hurt anything, but you have to get the right gear in relation to your road speed, your Rpms should not drop or go up.

If Rpms are bouncing all over the place, than your really going to do damage, I don't make a habit of coasting down hills at highway speeds, You still have better braking on hills with engine in gear, and if you know what your doing, better braking by down shifting.

I have allways prefeared a manual transmisson and the 6sp in my 2500 hemi is a blast to drive.

trust me, your truck is still using gas when you are coasting....the injectors do not shut off. why do people that have loud exhaust still have an exhaustnote when they are downshfting then? cause the engine is still firing...