Why do cars with automatic transmissions have tachometers?

Here's another idea. After cleaning and adjusting throttle body, removing and plugging a vacuum line on the throttle stop, the final adjustment calls for holding engine speed at 2500 rpm, then releasing the throttle and checking the engine speed, then loosening a small locknut and adjusting. Tachometer was helpful.

Reply to
nospampls2002
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But there are many models that don't offer ANY manual transmission option AT ALL, and yet they have tachs.

Reply to
Steve

It could be to make the driver think that the car is "high end" or "sporty".

I can't think of any other reason why a Ford Taurus, which only comes with an automatic transmission, comes with a tachometer standard, but a Ford Focus can be equipped with a manual transmission and no tachometer.

Reply to
Timothy J. Lee

Steve wrote: Agave wrote: It's more cost effective for the manufacturer to include a tach in all models where a tach would otherwise be an option. But there are many models that don't offer ANY manual transmission option AT ALL, and yet they have tachs.

In keeping with my prior opinion, consider not just a specif model, but also...

"similar" models, for example the Taurus and Sable as well as the Canadian, European, and other market varieties internationalization of auto manufacturers, for example Ford and Mazda - the Probe and MX-6 cross model pollinization a US model may not offer a manual transmission, but an international market model may

I'd argue that very few people actually need a tach, regardless of transmission type.  As others have pointed out, with most new cars/trucks having rev limiters, a tach is a "nice thing to watch", but not very useful, as well as how many people and how often does one red line their engine.

I think you can blame market research, focus groups, product testing, grabbing a piece of the after market pie, business decisions (e.g., "I'll give you a deal on 10 million fuel gauges, if you buy 3 million tachometers."), and just the general American mind-set of wanting things you don't really need for the reasons why there are tachs in cars with automatic transmissions.

At this point though, I think most people would notice that they didn't have a tach...even though they might not have a clue what it does :).  I commend you for noticing just the opposite and questioning the meaning of things.

Now, if someone can tell me why people don't use their cruise control, I'd be interested.

Reply to
Agave

where a tach would otherwise be an option.

ALL, and yet they have tachs.

Probe and MX-6

model may I'd argue that very few people actually need a tach, regardless of transmission type. As others have pointed out, with most new cars/trucks having rev limiters, a tach is a "nice thing to watch", but not very useful, as well as how many people and how often does one red line their engine.

grabbing a piece of the after market pie, business decisions (e.g., "I'll give you a deal on 10 million fuel gauges, if you buy 3 million tachometers."), and just the general American mind-set of wanting things you don't really need for the reasons why there are tachs in cars with automatic transmissions.

a tach...even though they might not have a clue what it does :). I commend you for noticing just the opposite and questioning the meaning of things.

interested.

Most drivers push on the gas and the electronic transmission shifts properly and does what it is supposed to and little attention is given to shift points. The tach becomes for most people a bit of moving eye candy as the needle goes up and down betweeen 2,200 and 2,900 rpm in response to automatic gear changes.

The very limited space available in most cars could be more effectively used to display a couple of truly useful gauges and a small analog clock. Most of us really don't need (or know how) to monitor rpm's and time shifts accordingly. Ditching it may not be so easy because the tach has become such an automotive fixture that if it were eliminated it would be seen as step backwards.

Reply to
John S.

I have never known this to be the case. In fact, I was driving a rented Chrysler Sebring last week. Found an opening into traffic and punched the pedal hard. The tachometer whizzed up, as the engine also whizzed with a sound like a sewing machine out of control... but the car did not accelerate whatsoever for a good second after the pedal was pressed.

Is this normal? It's been more than a decade since I last drove an automatic. Do people really put up with this?

I would agree that oil pressure, temperature, and maybe battery voltage meters would be more useful than a tach... however we are entering a world where these things are either being removed or replaced with fake meters that give only a go/no-go indication because it is feared they will confuse the driver. Even BMW is now selling cars with temperature gauges that read cold, hot, and nominal, with no real steps in-between. This is horrifying.

--scott

Reply to
Scott Dorsey

Can't tell you about that specific car, but it sounds like a mechanical problem and not one that a tachometer could solve. If it really took a full second for the car to begin any acceleration at all then there is a problem with that vehicle. The numerous car's I've driven over the years have all been responsive when consideration is given to the engine and size of car involved. A Hertz chevy with a low-end v-6 won't have the same punch as a turbo-charged Volvo S80 T6. Both will accelerate when the gas is pushed however.

I test drove a Mercedes Benz about 4 years ago that had the poorest design for instrumentation I had ever seen. This car used a series of digital displays to show trip meter, temperature, etc. Truly a distracting and potentially dangerous design because you had to work through a couple of menus to find information that should be available at a glance while driving down the road.

Reply to
John S.

In my experience most cars with auto trannies do this, although of course some are better than others. One reason why I hate AT is because of this. My husband has a Saturn which is an ok car, but it does this. When he's driving and punches it to get around traffic, I usually can't resist a snicker along with a comment like "the hamster's running as fast as he can, poor thing", implying he's got a hamster in a cage instead of a combustion engine. I'm no perfect driver by any means, but I'm still better at timing my shifts (in my manual Dakota) than his auto tranny is. I've also noticed a habit many AT drivers have, of punching it and when the engine finally shifts, they let off the accelerator and slow down, thus rendering the whole exercise meaningless.

- Sharon "Gravity... is a harsh mistress!"

Reply to
Sharon

No, that is an improperly designed transmission. I drive a manual tranny very well. The main thing that annoys ME about automatics is that every single one of them I've driven (dozens) are designed to shift up WAY too soon.

You can adjust the upshift point somewhat by nailing the accelerator to the floor. Even if you do that though, the tranny will STILL upshift too soon. Or, if you are going slow enough, you could manually shift the auto tranny down to "2" or "1" until you are ready to let it upshift again. But if you have to put so much thought and effort into making the tranny shift right, what's the point of owning an automatic, exactly? The manual tranny is easier to control, if you HAVE to control it.

My point? Many of these AT drivers you observe, who you thought were letting off the accelerator, probably were not letting off the accelerator. More likely, they applied steady pressure to it. It is the *^*(*&#( automatic tranny that downshifts for about a half-second only to upshift again, unless the driver takes extraordinary measures to prevent such foolishness.

Yeah, there are some automatic trannies designed to be shifted often. Sometimes there's buttons on the shifter or even steering wheel, and sometimes the shifter itself can be moved into different gears, kind of like a clutchless manual. Call them manumatics or something. :) What's the point? Just buy a car with a clutch, so it will do what it's supposed to do, without having to jump through hoops to make it shift correctly. -Dave

Reply to
Mike T.

Because It's Cool. There doesn't have to be any other reason! Same reason passenger cars that can't possibly go fast enough to get airborn have spoilers.

Reply to
Michael Gallagher

Now that is an authoritative sounding but truly misleading statement. Since the power or torque curve is just that...a curve that begins at zero, any time the transmission shifts above zero it will be someplace in the power band. Its a question of where on the curve you want to shift. In addition to controlling quickly you can accelerate, the place you select on the curve will also govern how much fuel you burn and how much wear and stress you place on the engine. You appear to have little concern about fuel economy and engine longevity - playing the race driver seems to be your focus.

I have yet to experience that in hundreds of thousands of miles driving four cars equipped with automatic transmissions.

Interesting but rather bizarre statement that is not supported by the real world of driving that I've encountered. I drove numerous stick shifts before switching to an automatic several cars ago. The electronically controlled automatic of today does a far better job of shifting than most drivers I've encountered. Most guys with manual shift transmissions seem to like keeping the engine in a lower gear than needed presumably for the imagined race car thrills from hearing the engine at 4,000 rpm.

Whee...look everyone...I'm a race car driver 'cause I got me a car with a five speed, tach, spoiler and noisy exhausts to prove it.

Yes, there are workarounds, but driving a

A lushbox...??? A box full of alchoholics maybe????

Reply to
John S.

In article , John S. wrote: (snip)

(snip)

One thing I wish I had is a torque-speed curve and fuel efficiency map and whatever for my engine. I don't know where its most efficient points are, partly because I can't find that information out. Are there any good sources of this type of advice? My gears are set fairly close together so I have plenty of choice about RPM, I'm just not usually sure what the best option is. Normally for just cruising along at a steady speed I choose a gear that has the engine at between 2,000 and 2,500 RPM, but I'm far from confident that that's a good choice. I guess it varies from model to model.

-- Mark

Reply to
Mark Carroll

For 99% of us we are just cruising along or accelerating at a moderate rate. The shift points in most every car I've driven hold shifts at around 2,500 or so and thereby balance reasonable acceleration witth fuel economy. A simple press on the accelerator shifts down as needed.

Reply to
John S.

OK, I have to ask what the goal is by maintaining an artificially high rpm all the time. If you are running along at 3200 or 3600 rpm when you could be in a higher gear you are wasting gas and inducing more wear on the engine.

You say that the formulas will get you pretty close to where you want to be, but what will that level of rpm result in. If you are cruising down the highway at 60mph in 3rd gear to maintain 3,600 rpm what is being accomplished. There was an urban legend that lasted for decades about Porsche engines having to be run at 3600 rpm or higher all the time or the lower end would fall out. Lots of guys wore those boxer engines out prematurely as a result.

If you can't find

Reply to
John S.

Tell that to your local legislators who thought it necessary to mandate that you waste fuel in order to minimize safety and maximize revenue to the local governments and maximize carnage on our highways. In other words, you are looking at this wrong. I'd gladly upshift and drive safely at the most fuel-efficient speed of my engine in overdrive gear, if it was legal for me to do so. [Often, I do so anyway. :)] But at 78MPH, I am risking my license by driving in a very safe, sane, logical and fuel-efficient manner in over-drive.

Yes, I could do 55MPH in 4th gear everywhere. I would get decent fuel economy that way. But I'd have to put up with the extra engine noise generated at 3500RPM, while it's taking forever and a day to get anywhere. Plus, it's harder to hold a constant speed in 4th gear. Because I'm lazy, I generally shift up to overdrive even at relatively low speeds like 55MPH. But then, I pay for my laziness at the gas pump. The only time I get really good gas mileage is when I'm in a hurry and not as worried about getting hassled by the cops. IF I can maintain an average speed close to 78MPH for long enough, my MPGs go way up. But again, that's not exactly legal in most areas of the U.S. -Dave

Reply to
Dave C.

The following service procedures made mine a great deal more responsive, overcoming the characteristics you describe to the point that the transmission will hold the gears for better acceleration when desired to the point of maximum safe engine speed, downshift quickly when appropriate, and upshift early under light acceleration to maximize fuel economy.

1) put a piece of 2x4 and a concrete block to hold the gas pedal to the floor, then check the throttle butterfly valve for full opening at WOT. I found a cable adjustment that needed to move apx. 1/4". The transmission shift cable was also linked to the same assembly, so once the cable was adjusted, the trans.cable was fine. 2) factory service manual lists a number of procedures for cleaning the throttle body and adjusting the throttle position sensor (TPS) and I performed all of them with the aid of a digital multimeter including an audile continuity test. The TPS position was off by a few thousandths. Once the IDL stop was set correctly, the reading at WOT was fine. 3) there are some tiny orofices in the throttle body that direct vacuum to the EGR vacuum modulator. After following directions and cleaning with carburetor cleaner, then blowing out the passages with compressed air, one of the smaller passages emitted a burst of dark colored fluid

- presumably gum had been occluding that port to some degree if not completely blocking it.

4) adjust throttle stop at vacuum dashpot with vacuum line removed according to directions. As stated, transmission now shifts exactly as one would wish, although it has taken practice to learn the throttle mapping, so as to be able to feather the downshift points to activate or not as desired - roughly between 50 - 60 per cent throttle opening.
Reply to
nospampls2002

your model may differ, but I found the original factory marketing brochures for that year contained graphs for torque and horsepower - brochures found online.

Reply to
nospampls2002

Sun, 18 Sep 2005 07:52:40 GMT:

For those of us who do not hear well, it is a great visual aid. If you have ever had the MLPS go bad and act up on a Ford, you know one of the reason it can be important.

Lugnut

Reply to
lugnut

What the hell does 78mph have to do with anything. Put the car in drive and most likely at 60mph the engine will be turning a very fuel efficient 2,000 rpm or so. Push the car to 78 or whatever magic number gets you off and the car will be much much less fuel efficnent. In simple language even you should be able to understand the car will burn more fuel to traverse the same distance at 78mph as it will at 60mph. That is a well established fact.

Oh gawd, it is YOU again. The brainchild who thinks he understands engine efficiency.

Because I'm lazy, I

Reply to
John S.

Most cars today use torque converter lockups to bring rpms down to around 2,000 at 60mph and be reasoably fuel efficient. Most manual transmissions today have a built overdriven 5th gear if that is of any help. Whether the car uses an overdrive or not is not as important to fuel economy as how factrs like the overall drive ratio, number of gears available, the circumference of the wheels, the engine power and size of the vehicle are tied together.

Reply to
John S.

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