I don't like autos

[landspeed]

Just to say, my current car is an auto, with the following specs:

2.0i multipoint, 8 valve.

4 speed (3+overdrive) gearbox, with lockup only on overdrive, only at 45mph+

And, I have found that, if I use the SuperMID to try different techniques, going slower (with engine -on and engine off coasting) is about the same as racing hard from the lights, going faster, and so on, on the same daily commute! I just can't make my MPG go any higher.

What I think is happening is this:

When cruising at low RPMs, the torque convertor slip becomes a greater percentage of total RPMs, so at low RPMs, efficiency DROPS due to the torque convertor.

At high RPMs, the engine is less efficient... but the torque convertor is 'wasting' less of the energy.

Therefore it makes no difference what RPMs you are at because the torque convertor efficiency (better when higher RPMs) and the engine efficiencies (worse when higher RPMs) cancel each other out.

Also, as you accelerate with more throttle, you get higher engine efficiency. However, when you accelerate with more throttle, the torque convertor slips more as well. Again these seem to cancel each-other out.

So overall, My range of fuel usage has been '1.450 litres' (on an uncalibrated SuperMID) for the best journey, and 1.550 litres (on the same SuperMID) for the worst journey. I have managed to get 1.650 litres with lots of traffic but that is another matter.

Any ideas on how to get past this block? I have a long drive at 45+mph coming soon so I'm hoping that will be good, but town driving in an Auto is a joke (this car is basically mechanically the same as my last Bluebird, except it is an auto). Yet it gets half the MPG!

[s1120]

I have found the same thing with other cars, I seem to get the best mpg at 45-50 range. at that point the TQ is locked, tranny is in OD, and the motor sill is running pretty low RPMs

[rh77]

That sounds like a miserable transmission arrangement.

I too suffer from the auto (4-speed with 3-point TC lockup in gears 2-4, and "Hill Logic Control").

You're at the mercy of the transmission control system unless you find an aftermarket control unit. If it's something you're interested in, products may be out there for full control over the auto -- including TC engagement whenever you'd like. Someone here was selling a device similar about 6-months ago, but none for your application, IIRC.

Another route would be to play with the throttle linkage tension (if so equipped). Depends on the application...

What I do is set the tension as high as possible -- that way there's plenty of fluid pressure for shifts, and the TC engages as soon as 35 mph hits (and other variables are satisfied). Downshifts aren't a problem since the car's torque is high enough -- this is generally a concern with tightening the cable.

City Driving: I accelerate to where I think the car will shift into the next gear at throttle lift: (1-2 is manual by the gear selector and forces into 2nd) -- 3rd gear disables hill-logic, and "D4" is the usual placement for cruise.

There is generally a near-immediate shift into 2nd with gear selector "2" (about 10 mph), then into selector "D3" at 30 mph, lift, it generally shifts, then into selector 4 after the shift, then around 30-35 lift again, shifts to 4th, and at 35mph the TC generally kicks in. Accelerator action is generally TPS of 20-25 until cruise, then to 14-20 to maintain speed. The goal is top gear and TC lockup as soon as possible.

It may take a while to find out what works -- it's frustrating in the meantime, but hang in there!

RH77

[MetroMPG]

Yikes. Doesn't sound like fun, landspeed.

If I were forced to drive an auto, I'm sure I'd be looking closely at modding the shift points or making it so I could force t.c. lockup at will.

Still, you're doing well above EPA.

[ffvben]

my auto ranger seems OK, drive a 4-5 miles and converter locks in at 45ish. driving my wifes xterrra, i was watching rpms around 50mpg it was 2200, it seemed kinda high. after driving 15-20ish miles after my ranger would lock in it finally locked in dropping to 1800rpms at the same speed. dam that took forever to warm up.

[Gearshredder]

is it feasible to switch out the auto for a manual?

[landspeed]

I'm getting a Bluebird Attessa Manual soon - although I might keep 'Bluey II' as well. The Attessa means it is 4WD. It comes with no engine, and I was only getting it for the air con to fit to my car. However, I'm seriously considering putting in another engine, as the shell (appears to be) very good.

If I end up not putting in another engine and using that car, I will take all I can from it to upgrade my new Bluebird... In particular, the manual gearbox (it is reconditioned, and is worth keeping just for that reason), lights, electronics, air-con, etc, etc.

If I had my own workshop, I would take the rear axle from the 4WD, and connect that directly to an electric motor, and I would get a manual gearbox for the front 2 wheels. The electric motor would be for short journeys (or, even on long journeys, I could do the first few miles or so on electric to reduce the overall MPG, also I could do regen charging down any hills I find).

Gearshredder - to go to manual, I need a new engine computer (not that expensive secondhand), I need a new gearbox, mountings, flywheel, driveshafts, gearstick + the linkage for that too. I wish I could do it, but I don't have a workshop... or a spare car :(

To drift slightly back on topic... I just went out for a drive on a road where I could keep the gearbox in 'lockup' mode, so I drove at 50-60mph most of the time, and got about 35.84MPG (us). This is better than I have been getting - however, it really does seem this is about the highest my car will go :( and it is nothing compared to the MPGs I was getting in Bluey I (see my signature!)

[yi5hedr3]

Autos aren't that bad. Sure you can get a few more mpg's per gallon with a manual, but in your case, get a ScangaugeII and air up those tires to maximum sidewall specifications. You'll see a great improvement!! :)

[Pete]

The lock up clutch in an auto is miniscule compared to the standard clutch in a manual trans.

This is the reason the lock up point is only available in the highest gear and at low throttle (read low torque) openings.

Manual overrides can be made to work but you may destroy the clutch in short order as a result.

Pete.

[kamesama980]

autos are less efficient because of inherent friction (moving parts), fewer gears, and Torque converter....plus they weigh twice as much on average. They're also much more sensitive to wear, temperature, and fluid condition.

I don't like them because I tend to have a more spirited driving style and nothing is worse than being on the edge of traction around a tight corner and then the trans decides to shift..... now you have to get your car out of the ditch. Trying to control a car with a torque converter is like trying to pull something into place with a stretchy rubber band instead of a static rope.

[landspeed]

On my car... the lockup is actually part of the torque converter! It is available in top gear, at any throttle opening (and by design disconnects whenever you let off the throttle), and the same gearbox was used on the 3.0i V6 model :)

The clutches, on the other hand, aren't great (see bignissans.org.uk for a description of the gearbox and the problems it has when asked to handle a V6!). It was *very* advanced for its time... and therefore has its problems if pushed too hard.

I have just got another copy of the service manual, which includes full stripdown/rebuild instructions for the transmission. When I get time... I will see how easy it is to get to the lockup solenoid!

yi5hedr3 : My tyres are pumped up to 40PSI (that is daring with the sidewall pressure being 35PSI). It clearly made a difference from 28PSI... I can now coast down a multistorey carpark at work, and do about 5 floors before restarting the engine, prior to increasing the pressure, I could only coast about 1.5 floors before the car stopped.

My next tyres will be LRR with the highest sidewall pressure I can find. 35PSI is a joke!

P.S. I didn't get that manual transmission in the end, but am on the lookout for a FWD manual to fit to this car. Also wondering whether to get a 3kw motor fixed up to the car, and park in the sunlight (I worked out, I could collect enough power with 100W of solar panels to do twice my commute per day, so could end up paying v. little for petrol, using it only for acceleration, and then using the motor for most of the journey).

[Hateful]

I have a 4 speed auto in my Cavalier. If I'm watching the ScanGauge and see it's not coming out of the 20's relatively soon, I just let off the gas and lightly pump it. This gets me up into the 30's more quickly than just holding the accelerator down through the gears.It may not be as good as a manual might be,but I wouldn't say I have no control of the gears changing.

[landspeed]

My transmission is so old, the torque convertor is (as new) very slippy, and lock-up engages only at highway speeds. I just looked through the service manual - no way at all to change lock up (all hydraulic, the only solenoids are for preventing lockup occuring. I'm going to unplug that one so I can have lockup when cold etc :)

I have noted that, there is an electronic control box to replace the hydraulic control box (and I think the rest of the transmission is the same). I'm going to research this, in case I can get one for cheap from a scrapyard. If I did this, I would be able to control the lockup.

The way to control the lockup on the hydraulic box, is to engage it 'all the time' from the hydraulic viewpoint, but then, set the lockup-cancel solenoid to always be 'cancelling' it, unless you are pressing the lockup button (or switch which can be used when cruising on the highway). The other good thing is that the lockup would disengage when you stop the car anyway (it uses hydraulic pressure - if you tried to engage it at very low RPMs it would probably just shudder or slip).

[itjstagame]

Yeah, I went with grill blocks and other mods to try and get my truck to warm up as quickly as possible, so it will engage TC lock as quick as possible. Right now it's about .5 miles or so from cold and before it engages I go about 5 MPH slower.

As far as around town I've tried various types of acceleration, the best seems to be to accelerate fairly quickly to 35ish and then be very light on the gas. Even though I can get the TC to lock at 42 or so with a light pedal (less torque) it's hard to maintain and there's always a redlight coming up soon anyway, so I found that sticking to 30-35 (about 5-10MPH below the 40MPH limit) I can pretty much maintain that speed and time the red lights, etc.

As for TC inefficincy, during hard acceleration it actually gives a boost to the torque to the wheels, as you said it's only really at low rpms or low torques when not TC engaged that it's really bad. That's why I accelerate fairly quickly (but not WOT) and then am very moderate. Nothing seems to help too much though....

[gto78]

I thought that vehicles all mostly used electric to engage the TC clutch. One of the things I did when racing cars was install a toggle switch on the dashboard and directly wire it to the TC solenoid. That was on an older rear wheel drive GM car but still the same concept as many newer cars. By having it controllable manually this allowed me to engage it in any gear, for instance driving in slow traffic below 45 mph I could be in a lower gear and still engage the TCC. The down side of course is remembering to turn it off between shifting gears, and when stopping at a traffic light. If you leave it engaged while stopped then of course it will stall the engine. Leaving it engaged between shifts makes it shift much harsher.

[DarbyWalters]

YOu could invest in an aftermarket Torque Converter with a lower stall speed. In the US Suncoast and others make them to your specs. Many Diesel owners here get a better TC just for that reason...slipping also causes tranny temps to rise which is a bad thing.

[landspeed]

I thought that vehicles all mostly used electric to engage the TC clutch. One of the things I did when racing cars was install a toggle switch on the dashboard and directly wire it to the TC solenoid. That was on an older rear wheel drive GM car but still the same concept as many newer cars. By having it controllable manually this allowed me to engage it in any gear, for instance driving in slow traffic below 45 mph I could be in a lower gear and still engage the TCC. The down side of course is remembering to turn it off between shifting gears, and when stopping at a traffic light. If you leave it engaged while stopped then of course it will stall the engine. Leaving it engaged between shifts makes it shift much harsher.

I thought that too - however 'mostly' is the operative word :(.

My car has the lockup controlled by hydraulics - there is a 'lock up solenoid' which is electronically controlled. However, what this solenoid does is change a fluid path so it cannot enter overdrive.

It will only try to enter overdrive if doing just over 80km/h in overdrive. The lockup solenoid merely stops this happening.

One interesting thing is, if it is disconnected, it enters lock-up when cold, but an annoying thing is that it won't disengage lockup when the accelerator pedal is pressed.

I might install a switch to allow lockup when the engine is very cold, and then switch back to normal once warmed up to allow it to disengage when going down a hill in fuel-cut mode (since the engine then turns slower, allowing fuel cut with less engine braking). Obviously I coast down hills with the engine on (or off at 60kph or below) if I don't need to stop at the bottom, or slow down.

[KrazyDawg]

Autos aren't that bad. Sure you can get a few more mpg's per gallon with a manual, but in your case, get a ScangaugeII and air up those tires to maximum sidewall specifications. You'll see a great improvement!! :)

The ScanGauge isn't compatible with my 1995 Civic EX. :(