RPM gauge....what is it's purpose

kia
sedona

#1

I have a 2002 Kia Sedona mini van. on the dash there is an RPM gauge. Can someone explain to me why a van would have this and what purpose it serves?



in addition, i have noticed that my RPM’s are a bit higher in the morning now as the temps are colder then once the car warms up, should it be that way?


#2

To tell you how fast your engine is turning. It can be useful for diagnosing problems with your automatic transmission - -if it’s stuck in 2nd gear and you have the radio blaring, you might not hear the engine howling, but you’d still be able to see that it was at 6k rpm.

Yes, it’s normal.


#3

The tachometer on most cars is there only for marketing reasons and because some buyers think they need it. It can sometimes help you to diagnose that you have a transmission problem starting.

Your idle RPM should be higher when the engine is cold.


#4

It’s there to fill a hole on the dash and to give you one more thing to worry about…


#5

It’s a gauge that, among others, allows you to monitor for yourself what the engine is doing.

You may think I’m foolish or too ‘Type-A’, but I’ll add gauges to a car if it doesn’t have the one’s I like to see, like an oil pressure gauge, coolant temp gauge, and ammeter/voltmeter. Cars of the 80’s and early 90’s were notorious for only having idiot lights to cover these. But by the time the light went on, the damage (usually expensive) was already done.

As sophisticated as the ODB-II systems are, they still have a lot of ‘holes’ in the system that allow dangerous conditions to develop before turning on that CEL. A good set of gauges can warn you of trouble before the computer lets you know.


#6

Warning a driver of “dangerous conditions” in regards to their automobile is not an accurate description of what the job of the OBD-II system is. It is a required system who’s job is to tell the driver when an emissions system failure is present.


#7

With an automatic transmission, it is almost useless: it’s mostly marketing. But you can use it to improve gas mileage. Look at the RPMs while you are cruising on the highway. If you get much over 2000 RPMs, you are using too much gas. If you aee at 2500 RPM, you could be going 80, while at 65 to 70 you are likely a bit below 2000. Or so it goes with my car. Slow down and you will increase gas mileage.


#8

oldschool, it is much more than that and you know it. It triggers many codes that have nothing to do with just the emissions system or the overall effects of emissions. It is an engine management system, and monitors the engine on levels that a full set of gauges cannot give to a driver. But, it doesn’t always set a trouble code or warn the driver of problems developing with the engine. It doesn’t monitor the oil pressure, fuel pressure system, and will not let you know the engine is running too hot until it affects a system that will trigger a trouble code.


#9

Look at it this way,OBD-II would not exist if emissions standards were not forced upon the manufactures. The gov. wanted a system on every car to make sure a driver knows when a emission system fails,and technicans had a way of troubleshooting these systems, that was the reason for creating OBD-II.Manufactures are free to add enhancements to the systems but the base system came about due to a need to monitor and repair emissions systems.

The only reason I point out this distinction is that to many people misinterpet just what that “check engine” light is capable of telling you about your car. It will not tell you why your car won’t start, it will not tell you why you car died, it will not tell you any system needs to be “checked” but an emission system. When that “check engine” light comes on it is not telling you “hey I need a new serpentine belt because the one currently installed is going to break”. It will tell you,“I am running lean” or “I am running rich”,why would the gov. want this to be known? well the reason is that the cat.converter does not work as designed when rich or lean conditions are present.It is not telling you this because engine damage is a possibility.

The “check engine” light should not be viewed as a indicator of a condition that is harming an internal engine component, but it should be looked at as a system that is saying to you (and emphasized when flashing) “Hey you are destroying your emissions system”.


#10

If you just put your auto transmission into “D” and don’t ever shift into 1, 2, 3, etc. then you really don’t need a tach at all. In many parts of the world drivers still prefer manual transmissions and for them the tach is useful. American shoppers see a tach as “sporty” even in a car with an auto transmission, therefore many cars come with tachs.

All my cars have tachs, 2 are auto trans and 1 is manual. For the manual I use the tach routinely. On the auto trans vehicles I do use 2 and 3 frequently when sporty driving one car. The other is an SUV and I like to keep the rpm’s around 3K when I need power when towing the loaded horse trailer. I could easily live without the tachs in the auto trans vehicles, but I’d miss it most in the manual Civic.


#11

OBD-II is based on the Gov’t mandate to monitor emissions, true. But, there was a manufacturer’s proprietary ODB-I that was fairly successful before the Gov’t mandate, although grossly limited. With the Gov’t mandate, they improved on the concept greatly. OBD-II does not just exist for emissions only. The Gov’t mandate did require these systems to monitor the emissions in real time, but the manufacturer’s also added much more diagnostic features that are a world apart from the OBD-I systems.

Here are a few codes that the computer will set that have nothing to do with emissions:
P0218 - Transmission overtemperature condition
P0512 - Starter Switch Circuit
P0534 - Air Conditioner Refrigerant Charge Loss
P0560 - System Voltage Malfunction
P0574 - Cruise Control Related Malfunction
P0705 - Transmission Range Sensor Circuit malfunction (PRNDL Input)


#12

lol Caddyman! However i do find it useful on icy roads. It gives me an idea of where my traction n brakes are best off. mpg? shifting point? Manual transmission


#13

My exhaust may be a bit 2 quiet


#14

Caddyman as in Cadillac? i have a friend that will be leaving us and would love for his Caddy 2 go to a caddy guy. they only made 500 or so… i forget what it is. i tried 2 pm u.


#15

A tach is not entirely useless. It suggests a relationship to racing and therefore adds a little macho to a soccer mom car.


#16

it is really called a tachometer, and have you ever heard of google?


#17

I grew up driving clutch cars and learned early on to ‘listen’ to when the car needed to shift up. Never, ever had a need to ‘see’ the rpm. To your point, in an automatic, it’s mostly useless unless (like has been mentioned) you spend time in “1, 3, or 3”, (like pulling a trailer up or down a hill, for example).


#18

If the knucklehead minivan driver put the van in a lower gear and leaves it there on the highway.

There is a possibility beyond noise and some vibration they may notice the RPM’s at a much higher level than usual.

I typically drive manual transmission vehicles as a choice. However when borrowing automatics I never look what gear I am in, and simply slip the lever down until it stops. For whatever reason I find a lower gear not the top gear is indented by feel on many automatics. I either notice the tach if quiet vehicle, vibration, or noise before I put the automatic into top gear.


#19

I can see it on say a sports car…BUT A MINI VAN? Also i don’t drive on the freeway and since I bought it I have not had it above 55 miles per hour as I only drive it to and from work (26 miles total) and to the store and such all in town. So it driving hard and fast doesn’t happen…


#20

How exactly was the OP supposed to know to google “Tachometer” if they didn’t know it was called a tachometer?