What Causes Rpms To Jump While Driving?


What is neutral in cars for?

Before I use to think my friend was driving a stick cus he would go from D to N a lot. I asked y he uses it he said it saves gas. Is it safe to use N?

Neutral has a few different purposes. For a Manuel Transmission (Stick) Vehicle, it needs to be in Neutral to start up the vehicle, so it doesn't start in Gear. That's why a Stick Vehicle will not start in Gear.

A big reason is for the switch in gears, say for example, you're rolling back, if you go straight from Reverse to Drive, it can crack your Transmission Case, mess up your Transmission, costly stuff... Also, if you were Driving and accidentally hit your Shift Knob/Handle, you would completely destroy your Transmission if you bumped from Drive to Reverse going 50Mph...

Another reason for Neutral, it allows Overdrive, say you're going down a steep, icy hill, if you were to use Low (on an Automatic) or 2nd, or sometimes even Drive, if you don't have an option to turn Overdrive off, then it can cause your car to slide when you hit higher RPMs. It's hard to explain, but if you use Neutral, it's like having Overdrive on, it'll drop your RPMs down to around 1,000RPM, which it basically Idle, while your driving, you have much less control of your car when you do that though, your car will continue to gain speed going down a hill, because there is nothing restricting it from doing so, so basically your car will just roll, and keep going as long as there's momentum.

Your friend said he gets better Gas Mileage, and he probably does, but most likely he switched from Neutral to Drive quite often, so in the end he probably averaged out on his Gas Mileage, not necessarily saving any Gas... But, Neutral will drop your RPMs, the lower the RPMs, the better your Gas Mileage. When your Car's in Neutral, it's not feeding nearly as much gas into the engine, because it's not using nearly as much power.

Generally, if you're just driving on the road, in the city or whatever, Neutral isn't the safest thing, it's definitely not made for that.

Hope this helps!

What would cause Chevy S10 RPM gauge to stay below 1000 while driving?

1996 Chevy S10, 188xxx Miles. Had intake manifold gaskets replaced, now RPMs just sit below 1000 until I'm driving for a while, then they'll jump up to 3000 and back to 1000 off and on. Truck is running normal, nothing seems odd besides that. Possibilities?? Thanks! Yes , it does have a distributor.

Double check the wiring that runs near the distributor cap. I had a friend do a tune up on his s-10 and he accidentally got a wire pinched under the cap. He called me later complaining that his tach was jumping around erratically. I when over and checked the work he performed and found the wire. I removed the cap, dislodged the wire, and reinstalled the cap. Everything is working good now.
Hope this helps. Christopher

What if you had an engine that could produce 11,190 km/s what would that equal in rpms ?

The Earth's escape velocity is 11,190 km/s or 6,961 miles a sec. If a stationary engine could reach that equivalent in rpms what would that be if the gears were 12cm across ?

w = V/r = 11.19E6/0.06 = 186.5E6 rad/sec = 1.781E9 rpm

2000 Nissan Xterra problem?

I have a 2000 Nissan Xterra with approximately 157,000 miles on it. I have been its sole owner for 11 plus years with no major problems whatsoever (a few stupid things here and there). In August of this year the AC went out. It blew hot air only. Then I noticed it wasn't itself. Kind of sluggish, almost like something was clogged. I was driving up a steep highway incline and noticed it wasn't as powerful, it was moving, but I didn't feel the power. Fast forward to September 30, and I bring it to the mechanic (the ABS light had come on, but that is unrelated) to be fixed, ABS and AC. Problems fixed, AC was given a charge. Went to pick it up on Oct. 1 and upon starting it the "service engine soon" light came on. Mind you, I have not once seen this light on in my car. Since I was in the repair shop's parking lot I went in and told them. A tech came out and ran a scan that showed it was the oxygen sensor. He reset it and told me if the light came on again I would probably need a new one. I left thinking I will need to replace it in the near future. AC was working fine. It was pretty weird about that light coming on though (especially after a charge for the AC). Oct. 6 I was driving and all of a sudden my car jolted forward with my foot off the gas. Didn't experience it again on my drive. Oct. 7 I was driving it and the car went haywire; jolting, stalling, bucking. Oct. 8 brought it back to the same mechanic and it turns out to be the distributor. Refurbished distributor put in on Oct 12. Went to pick it up and AC is not working again. I didn't even tell the mechanics because I didn't want to make things worse with my car working properly. The car is not driving right now though. It jolts a little while driving, when in a turn I feel as though I am driving on ice with the way it will take off seemingly out of my control. Today it jolted and I smelled a smell of what seems to be oil on top of what it normally smells like under the hood (I know every little detail about my car) and it just doesn't feel as powerful as it was. When starting the car, the RPMs shoot up over 2000 and settle on 1300 when it only used to go to 1500 and settle on 1200. It seems the RPMs are lower while driving though. It doesn't seem to want to go above 2000 without an extra push, yet does it when starting up. It seems screwed up. The mechanic checked for leaks before giving the AC a charge, but could that have caused the "service engine soon" light to come on and the distributor to go? After the distributor was replaced the AC isn't working again. Could these things be related? Could there be a leak or is it likely a sensor? The timing belt was never replaced. O2 sensors never were either. Nothing on my car has really ever been. Could that charge to the AC have surged the distributor? Could the charge to the AC have done something? Could the AC have gone out because of a leak somewhere? I feel like this problem is so stupid. If I'm not looking at the RPMs I generally don't think anything is different (except for the jolting occasionally), but the RPMs being so erradic pisses me off.

the words that stuck out to me were "jolting, bucking, stalling"..i had that happen to me on a grand am and it was a transmission problem--they said it was the TCC solenoid..got it fixed and no problems since

should i drive in D or 2?

my friend drives around town in 2. i just always keep it in drive. which is better? we both have 6 cyl. merc/cougars coupe's.

Depends where you drive. 2 is better for going up hills, but D is probably better in general, depending on how fast or slow you go (the slower the better, for 2) . At higher speeds, driving in 2 will keep your RPMs high, using more gas than D, and if you don't need the power, is a waste of gas and a wear on your engine/transmission.

If your tach is 3k RPM's or more when running in 2 around town, I'd say that you're driving too fast for 2, and should be in D in regards to gas consumption and wear on your engine.



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