RPM = number of Revolutions Per Minute. Most commonly an acronym for engine crankshaft speed.

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Is it harmful to drive at high rpms

Does driving at high RPMs (3000-3500) in a manual transmission car cause any extra wear and tear to any mechanical parts? It obviously hurts gas mileage, but does it hurt anything else?
11
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4answers
22k views

Engine power specification at different rpm?

Car companies advertise power of an engine at different rpms. Car 1: 80 PS at 6000 rpm Car 2: 85 PS at 6500 rpm What does the power at different rpm mean? Does it mean Car 1 has better power than ...
10
votes
1answer
86 views

How does the tachometer on my dashboard actually work?

Recently, I asked a question about the speedometer, how it works and how accurate it is. But that got me thinking... how does the rest of the dash actually work? I understand that the RPM measurement ...
8
votes
3answers
121 views

Why does my RPM drop when sitting idle at traffic lights?

While I'm sitting idle at traffic lights I put the car into neutral. The engine stays idling at about 1000 RPM. However every now and then it drops down to about 500 RPM and then quickly back up to ...
7
votes
1answer
4k views

Engine revs up when braking

Background: 2012 Honda Civic EX, 5-speed automatic, with no mods except a non-stock tire (ran over a large bolt). I keep it maintained per the manufacturer's manual and always see the Honda dealership ...
6
votes
4answers
648 views

2015 Honda Fit iVTEC - Shifted into 2nd Gear at Highway Speeds

I was just driving on the highway and went to pass someone uphill, so I went to put it into 4th gear (from 5th or 6th). I somehow made the mistake of putting it into 2nd and the engine screamed and ...
6
votes
3answers
3k views

Is it bad to drive slow at low rpms in 4th or 5th gear? Do you get better gas mileage?

Obviously running your engine at too high an RPM for too long isn't good. But what about running it too low? not so low that it stalls or lugs, but within around 1,000 RPM? Would you get better ...
6
votes
3answers
2k views

Minimum RPM at idle speed

Looking at wikipedia, For a passenger-car engine, idle speed is customarily between 600 rpm and 1,000 rpm. For buses and trucks it is approximately 540 rpm. In case of many single-cylinder ...
6
votes
3answers
2k views

What determines when an automatic transmission shifts?

I'm working on developing an automatic bicycle (mostly microcontroller based) and I'd presume I'd be shifting in a similar way to a car. So my question is, what factors does the transmission take into ...
6
votes
1answer
94 views

Can diesel engine be harmed as easily as gasoline engine by over-revving?

There is an excellent Q&A about why diesel engines have lower redline RPMs (about 4500 RPM) than gasoline engines (about 6500 RPM). The reason is related to the combustion of diesel fuel. ...
5
votes
2answers
422 views

Checking the motor's RPM without an in-dash tach

I'm going to be doing a carb rebuild this weekend on an 84 Ranger. The truck doesn't have a tach, but I'll be needing to read the RPMs to properly adjust the carb once its rebuilt. Is there a way of ...
5
votes
4answers
1k views

RPM bouncing when in idle, especially when AC in switched on

I have a diesel common-rail 1.5l engined car. Lately I am facing an issue where the RPM needle is bouncing in the tachometer when the car is idling. The normal idling RPM is around 820. When idling, I ...
5
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2answers
3k views

Why does diesel engine have redline much lower than petrol engine redline?

why do diesel cars redline at around 4500 rpm whereas petrol ones around 6500 -8000 rpm? Does this have something to do with the compression ratio?
5
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3answers
4k views

Does accelerating faster worsen fuel efficiency?

I've often heard that accelerating harder makes for bad fuel efficiency, but have yet to be given a sound explanation of why. Naturally this makes me question this advice. Now obviously when you ...
5
votes
1answer
1k views

Why doesn't my rev limiter bounce?

I have a BMW 630i Steptronic from 2007. If I floor the pedal in neutral the RPM is of course limited, but it doesn't "bounce" like regular rev limiters. Instead it keeps a constant and "clean" RPM. ...
5
votes
4answers
1k views

Why does the power output peak and then drop as engine speed increases?

I have been looking at the power bands for my car (2000 Opel Agila 1.2) recently, as I want to work out when it is best to change gear and stuff, as I have no life! This is the approximate graph I ...
5
votes
1answer
449 views

Engine revs to 4000 RPM without pressing gas pedal

I tried to start my car today but something strange keeps on happening. It turns on just fine, but once the engine is operating it starts revving to 4000 RPM even though I am not pressing the gas ...
5
votes
1answer
2k views

RPM fluctuation when maintaining speed in high gear

I recently got an oil change on my 2008 Audi A4 Quattro. Now I notice that when I am cruising in 3rd, 4th, or 5th gear (but not 6th), and I am at about 1200 RPM, the tachometer is not stable. The ...
5
votes
1answer
933 views

Suzuki GSR600 low idle revs and unstable

Just a week ago I noticed in my motorbike unstable rpm, +-300rpm. But today I found that the idle rpm are below 1000rpm, at some points around 500rpm (Normally is 1500rpm). I'm due for the annual ...
5
votes
1answer
698 views

Automatic: revs dropping then stalling when stopped at lights

Kia Sedona 2012 automatic. Drove 180 miles on a full tank of fuel without any problems. Started the car the next day and it didn't start cleanly but did eventually. Was waiting on the drive with the ...
3
votes
1answer
741 views

Does using the entire rev range of a car damage it?

On my standard 2000 1.2 Opel Agila, I often have to get to about 5000RPM to join a fast road on a steep (1 in 10) hill, as it is gutless on hills. I have to do this almost every day, and I have ...
3
votes
3answers
112 views

Should fuel pump noise be changing according to electrical load and RPM?

One thing that bugs me about my car is that the fuel pump noise is fairly inconsistent. Turning on the lights, aircon, defroster, etc. lowers the fuel pump speed and gives a lower pitched noise. It ...
3
votes
1answer
223 views

1980 Suzuki GS 850 trouble at high rpms

I have a 1980 Suzuki GS 850 and I am having a problem where the rpms spike when I really get on the throttle. If I slowly accelerate there is no problem, everything runs smoothly. When I'm on the ...
3
votes
4answers
1k views

RPM jumps up & back down at 40mph

My question is for a 2006 Dodge Magnum, 2.7 liter engine. Just over the past month or so, I noticed when I'm cruisung, just coming from a dead stop, when I'm at 40 mph my car kinda feels like it ...
3
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2answers
302 views

Do all engines typically support the installation of a crankshaft position sensor

I have recently purchased an 800cc dune buggy but unfortunately it doesn't come with a RPM sensor so I have been looking at my options in terms of installing one. In the process I have found that the ...
3
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0answers
264 views

1992 Mitsubishi 3000gt sl. no power and won't go above 2k rpm

I bought an automatic 1992 Mitsubishi 3000gt sl 2 days ago. I got it cheap knowing it would have problems, and that's why I'm here. When I put it in drive and slam on the gas the car just simply ...
2
votes
5answers
11k views

What modifications need to be made to an engine to enable higher safe RPMs?

I first had this question while playing a racing game - it was a touring race with BMW 320i's, and I noticed that I could rev up to 8,500 RPM before shifting gears. Now my car (an older 320i), ...
2
votes
3answers
395 views

How do I reduce engine idling rpm without stalling it?

Considering idling losses are present in every engine, reducing the idling rpm might be providing significant savings. But, as I noticed on my bike, the chances of engine stalling increases with ...
2
votes
4answers
203 views

Can 100% load be reached in neutral?

While searching for information about how is engine load calculated I came across this question which contains an equation for the ECU load calculations. As I understand it under fixed atmospheric ...
2
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2answers
1k views

Is alternator rating at pulley rpm or engine rpm?

I just got a new alternator for my jeep that says 160amps at 2k rpm. Is this rating for the pulley rpm on the alternator - or is it the rpm of the engine? Also, if the pulley is spinning slower than ...
2
votes
1answer
143 views

Installing an RPM meter

I need to install one in my car, as it doesn't have one, what modifications do I have to do? Edit: My car is: Suzuki swift 1996 But I would like the answer to be generic, as to what to look for if ...
2
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1answer
45 views

What is rev matching, and how do you do it correctly? [closed]

I understand that not doing this properly will destroy your transmission/synchros. What's the proper way to do it? I think I'm doing it right, but I've found most people's descriptions to be vague and ...
2
votes
1answer
2k views

Subaru Outback 1998 high idle rpms and CEL P0507

My wife's 1998 Subaru Outback threw a check engine light the other day, and when I read the code, P0507, it corresponded to a problem I'd noticed for a while: high idle rpms. The problem is most ...
2
votes
1answer
150 views

Tachometer doesnt show correct RPM sometimes

On my Honda CBF 150cc , the Tachometer shows RPM correctly when i'm at a constant speed. But some times when i slow down and accelerate the RPM Needle moves unexpectedly. (say to 0 even i'm at a ...
2
votes
1answer
33 views

Honda City vTec Slow Start

I have a Honda City 2005 vTec Manual Transmission Car, which will be due for servicing in another 1000KM. I am not well used to driving manual car and I face a lot of traffic everyday going and ...
2
votes
1answer
1k views

Clearing a P0507 on a Dodge Stratus

My 06 Dodge Stratus (4 cylender) is showing a P0507 off of the Torque app. My idle is sitting at near 1100 rpm versus the standard 800. I read up on the code and started looking for a vaccum leak ...
2
votes
1answer
8k views

Why does my engine rev up when I put it in park?

I've seen questions about engines revving when braking and when idling, but my engine revs way up (and stays up) whenever it's in park--whether on startup or shifting to park. It doesn't rev unusually ...
2
votes
4answers
4k views

Is starting idle RPM always lower in colder temperatures?

I've noticed that my 2008 Jetta 2.5L 5W40 generally starts up with an idle RPM of at most 1.2K RPM around the freezing temperature (say when the temp sensor reads 33°F), or even at just about 1K ...
2
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0answers
25 views

Increase of RPM meter after reaching my destination [closed]

I'm driving Camry 2001 4 cylinder, automatic gear. Just recently I noticed that after reaching my destination, when I put gear to P, I find the RPM meter increase to reach slightly lower than 2, ...
1
vote
1answer
58 views

What Means Fuel Shut Off?

What does fuel shutoff means? I searched it up before, but the answer is not what I'm looking for. For example: The Ford Lighting's fuel shut off is at 5,400 RPM.
1
vote
1answer
440 views

High RPM and engine heating on 2001 Subaru Legacy

I have a 2001 Subaru Legacy L station wagon with 143k miles. I do not know when the timing belt was done, or when the spark plugs were replaces last. I only know that the brakes, tires, and one of the ...
1
vote
3answers
681 views

Toyota Corolla 2011 not accelerating when on 60mph or above

I recently bought a toyota corolla 2011 s from a local dealer with 80,000 miles on it. In my test drive everything seemed normal and was satisfied with the deal. But on a recent trip when i actually ...
1
vote
1answer
44 views

RPM problem Ford 2009 Crown Vic

I recently removed the car battery and plugged it again. I then noticed that when I turn the A/C on the RPM goes up and down 1000~500 rpm and sometimes when I shift the gear from N to D or R the car ...
1
vote
1answer
124 views

Can frequent engine lugging lead to blown head gaskets?

I've heard that prolonged driving at low RPMs (AKA "lugging") can cause head gaskets to blow. Is that true and, if yes, can you provide a lowdown of the causality?
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vote
1answer
264 views

cause of Rough / fluctuating RPMs in low RPMs

It's not dying (hasn't yet) but when the car is idling or in low RPMs the car (Mazda Protege 5 2002) is fluctuating in RPMs. Also, the last start was rough. I've had issues with air intake before ...
1
vote
1answer
460 views

2004 LEXUS GX470

I have a 2004 Lexus GX470. I am having this problem where as I accelerate, my RPM goes up to like 5/6 and my speed is not going up. If I back off the pedal and try again it sometimes will ...
1
vote
1answer
100 views

2008 Ford Fusion throttle sticking?

I have a manual-transmission 2008 Ford Fusion SE. It's a great car but I have been having some problems with it recently. Firstly, the throttle does not seem to close when I let off the gas pedal. If ...
1
vote
1answer
3k views

Typically in what RPM range should one manually downshift an automanual transmission?

Related to this question and TMN's answer: What's a good RPM range to safely downshift an automanual transmission manually? My car does it for me when the RPMs get really low, but that throws me off ...
1
vote
0answers
33 views

Does “slogging” an engine (open throttle at very low RPM) increase mechanical wear? [duplicate]

When I was taught to drive, I was told that "slogging" the engine - open throttle at low RPM, e.g. 1000 RPM - was bad for it. Particularly when driving up a hill as that means you'll be stuck at that ...
1
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0answers
2k views

Fuel Consumption and other Fuel related data from basic OBD-II parameters [duplicate]

I want to know how can i obtain the values of Fuel Consumption, Fuel Economy and other fuel related information from basic OBD-II parameters like Vehicle Speed, RPM, TPS etc. I have noticed that not ...