16

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 is converted to a voltage. The voltage is fed to the moving coil. The coil creates a magnetic field. That field of the coil tries to align itself with the ...


9

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 pick up a "timing light" that has a tachometer function. Either of these tools have other purposes for a shade tree mechanic, so find one that you think you will ...


7

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 to get your RPMs. I'd be tempted to say your tach is out slightly. You could ask them about that. There is a smartphone app that you can use to gauge RPMs - ...


6

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. Positive and light go to the positive side of the battery with a fuse. Ground goes to the negative side of the battery or an unpainted part of the engine/body. Signal ...


3

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 sure I'm reading what I find accurately), then the sensor side is probably good since the ECU will be using the sensor for engine control and it sounds like ...


3

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 the 6 changes to a 7 then 8 in kilometers not every 100 metres... The distance shown on trip counters always shows a single decimal. Ie 345.1 km He is trying to ...


2

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 the piston is not happy trying to convert reciprocating motion to rotational motion(it is losing momentum) so as soon as you pull the clutch the rpm drops down ...


2

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 roll off, the engine and drive wheels are connected at a set ratio (the gear you're in) through the transmission. Neither are spinning independently. When you ...


2

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 the mechanic that the max rpms for this engine (CAT 3116) are 2800 RPM.


2

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, you won't be looking at the tach, anyway. That said, you could always put a couple of magnets on the flywheel (180* apart) and use a Hall effect sensor. Plug ...


1

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. Took alternator off and got it tested - was also fine. Put it all back together and had it tested - still fine. Only happened intermittently and when vehicle was ...


1

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 always changing, over time. Another point to consider is that most people tend to get information more rapidly from the position of hands on a dial especially ...


1

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 remove the screw to ensure it's not longer interfacing with the cable sleeve, there shouldn't be anything else holding it in. If it's stuck, it could be a matter of ...


1

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 wire. best way to isolate this is drive over a sharp small speed bump or 2x4 quickly and see if it reliably causes your gauge to fluctuate. it could be the RPM ...


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