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Questions tagged [tachometer]

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1answer
49 views

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

I have a Thomas 1991 school bus (36K gvwr) with a CAT 3116 engine and an Allison MT 643 transmission. I purchased it quite recently and when driving it on the highway, the engine RPMs are at 4000 ...
6
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1answer
71 views

Overlay tachometer with clutch plate RPM

I've been thinking about this for manual transmissions, to ease RPM matching. Has anyone ever seen an additional dial (on the same tachometer) that shows the clutch plate RPM? In order to match RPM, ...
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1answer
40 views

Is it 27K or 271K km?

The owner of this car says that his car has 27 thousand KM but to me it looks like 271 thousand km. Am I mistaken or he?
2
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1answer
508 views

Squealing and uneven idle, then tachometer drops to zero but engine keeps running

When I start my car, a belt seems to slip and then the tachometer reads zero RPM but the engine keeps running, but has weak power and only runs at low RPM. Any idea what's going on? The Symptoms: ...
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0answers
44 views

Tachometer Oscillating in Cold Weather

My 2012 Mazda3 appears to have some engine difficulty in cold weather (below 10F) when at operating temperature. As I hold the gas pedal steady to maintain speed, the tachometer will jump back and ...
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1answer
4k views

2013 Hyundai Elantra Speedometer, Odometer, Tach, and Gas gauge have stopped working

I am new to this site and found that someone has previously asked this question, but they did not indicate if they ever found a fix for the problem. Their post is here How Do Get My 2011 Hyundai ...
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2answers
427 views

Why are tachometers scaled in tens of hundreds?

I live in Europe, but I think it's not really relevant. Personally I use japanese car, which always have the rev-counter scaled in thousands: 1, 2, 3, 4, 5.. However, often you can see cars with RPM ...
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1answer
605 views

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

I am trying to remove the engine from a 1978 Yamaha XS400. The tachometer cable goes directly into the top of the engine - I'm guessing it runs off a worm gear on camshaft. There is a screw at a 90 ...
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2answers
331 views

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

I have studied that, RPM is the measure of how fast the Crank Shaft is rotating. Lets consider the following case. You are riding in some speed which shows the engine at 5000 RPM. Now you are ...
3
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2answers
3k views

Tachometer reading fluctuates at constant engine load/speed

The car in question is a 93 Miata, the tachometer needle fluctuates very randomly at random times (did it while idling and while I was driving). But the engine load does not change, it is the gauge it ...
8
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1answer
549 views

Connecting to the Battery During Emissions Testing to Measure RPMs?

When doing emissions testing, they connect to the battery, either directly, or using the cigarette lighter socket. I'm assuming that this is to measure the RPMs, as the only other thing connected ...
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2answers
8k 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 ...
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1answer
22k 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 ...