17 votes
Accepted

How does the tachometer on my dashboard actually work?

While i'm not sure if there are mechanical tachometers like speedometers electronic tachometers are quite simple. An electronic tachometer works like an old analog volt meter. The speed of the engine ...
vini_i's user avatar
  • 16k
9 votes
Accepted

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

You have a few options out there. There are meters that clip onto the ignition system that show the engine RPMs that are quite simple and cheap: Tach meter at Amazon for example... You can also ...
JPhi1618's user avatar
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7 votes
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Connecting to the Battery During Emissions Testing to Measure RPMs?

The voltage being a little low (13.75 is not low enough to be considered a problem in any case) is not going to affect their RPM reading - as it's the frequency of voltage variations that is measured ...
Rory Alsop's user avatar
  • 18.6k
6 votes

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

In addition to what JPhi1618 said... You can set any standard tach up with clips. I did this with a cheap tach when tuning my truck. They have 4 wires - positive, ground, signal, light. ...
rpmerf's user avatar
  • 8,443
3 votes
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Tachometer reading fluctuates at constant engine load/speed

You're getting an intermittent signal to the tach from the ECU or the tach sensor. If the tach comes from the ECU (which it seems to after a bit of Googling, but I don't know Miatas well enough to be ...
dlu's user avatar
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3 votes
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Is it 27K or 271K km?

The mileage shown there is 271000 ie 271k km. The rationale is that the total distance counter is always integer ie whole numbers. You could get him to take you for a test drive and discuss why ...
Solar Mike's user avatar
  • 34.7k
2 votes

Why Tachometer shows idle RPM range instantly when closing the throttle and clutching

From what I can understand, assuming the OP is curious as to why instantly pulling on the clutch the RPM goes down in a swift moment and not gradually? Simple: Inertia The reason for this is that ...
Shobin P's user avatar
  • 8,956
2 votes

Why Tachometer shows idle RPM range instantly when closing the throttle and clutching

It's a bit hard to understand your question, but I'm assuming you're asking about the RPM jumping between idle and back toward 5,000 when you disengage/engage the clutch. When you start the throttle ...
raydowe's user avatar
  • 3,012
2 votes
Accepted

Is 4000 RPM a normal rpm for a diesel school bus at 55 mph?

I had the mechanic look into it and he was able to determine that the rpm sensor on the engine was bad. He replaced that and a grounding wire and now the RPMs read perfectly. I also found out from ...
Joe B's user avatar
  • 195
2 votes

Overlay tachometer with clutch plate RPM

This is a bit long to fit in a comment, so: It would be cool, but, ultimately, you've got to get a feel for the rev differences between gears in your particular vehicle. Once you get in the habit, ...
3Dave's user avatar
  • 3,149
1 vote

Tachometer/Speedometer drop to zero and engine wont accelerate

I had similar problem on Hilux where rev counter dropped and battery and auto transmission temp level lit up whilst driving. Took battery in to check - it was flat and after a recharge, tested good. ...
Jacob's user avatar
  • 11
1 vote

Why are tachometers scaled in tens of hundreds?

Smiths (classic english gauge maker) had rpm * 100... Used in many british made cars. The numbers used are usually chosen by designers and what people are used to seeing which has changed, and is ...
Solar Mike's user avatar
  • 34.7k
1 vote

How do I remove a tachometer cable from a motorcycle engine?

Looking at a parts diagram, it appears that the screw is simply there to extend into a channel at the end of the cable sleeve, and lock the sleeve from moving out of the engine. If you can fully ...
raydowe's user avatar
  • 3,012
1 vote

Tachometer reading fluctuates at constant engine load/speed

Your car is pre obd2 which means there probably is no way to reliably look up what the computer is reading and what it is putting out to the gauge. So this can be a few things: It could be a loose ...
Cc Dd's user avatar
  • 2,879

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