94 Prizm 1.6L 4A-FE 5-spd manual

[cfguy2000]

The Geo Prizm is the same as a Toyota Corolla. I have 202,000 miles on my 1997 Corolla. Great little cars.

[Hubert Farnsworth]

Trying to alter my driving style had a detrimental effect on the mileage, when I tried to accelerate slightly quicker than before in order to test if it was possible to improve my mileage by limiting the time of acceleration by opening the throttle wider for a shorter time then closing it down, this last tank probably had a higher city/hwy ratio with heavier traffic as well. I did try some light neutral costing (with the engine on) as well as trying to stick to 55-60 for periods on the highway, but that was just too slow for traffic (its frustrating because people go far too slowly on the on ramp but then floor it and roar off, rather than accelerating smoothly from the base of the ramp, especially when its a long on ramp.

(By bad I mean it dropped by 3.54 mpg or nearly 1 standard deviation from the previous data point driven under similar weather conditions)

[MGB=MPG]

Hubert

i would like to find the strings describing the methodology of larger throttle application on acceleration resultant increased FE and try it too..
perhaps some kind soul could post a link.. for us..

sometimes theory in application can not meet or exceed experience and feel in real world.

i like to think with appx 50 years on the road and more than a million miles in Var. types equipment i do have a *feel*..

my preferred ramp behavior is to apply that amount of power required so that when i reach merge point to join the roadway i am at the same speed as road traffic.. and join..

i can recall with very large equipment merging into very heavy traffic applied full power and did not achieve required merging speed. , just stuck it in they could see me coming on down the line and gave way . [and cursed my soul i am sure]

remember on high speed roadways with heavy traffic there is the phenom of corridor or convoy effect . draft pull and draft push..

better to run with the traffic if you can ,, if you do not in Houston some Road Rage Cat may well target you with a 44 Cal ..

install a manifold vacuum gage .. drive with reference to it higher Intake vacuum=better FE .. forget the theoretical pumping loses ....unless you have high displacement with high compression its negligible .. so i intuitively know .

i might be right and i might be wrong
*lemon heads*

if i see the numbers laid out logical i CAN change my thinking.,

Regards

Michael

[Hubert Farnsworth]

That's the thing, I know it fluctuates rather wildly in the winter regardless of how I approach it, however I know that from my own experiences as well the theory doesn't always match expectations in the real world. Typically around down I try to shift before 2000 rpm, and from first into second either around 10 mph or maybe allow the revs to rise a bit to 2000 as well, when the engine is cold, which ever one feels smoother that day, then third by 15-20 mph, 4th by 25, (sometimes can drag 5th down to 25 or 30 from higher speeds but this I'm not so sure is a good idea) and into fifth around 30-35 mph around town, but on the freeway on ramps I'd hopefully start from fourth, but occasionally have to start from either a stop or having down shifted to third, then allow the 1.6L dohc engine to wind out to 3000 rpm on the way to 70mph as near as possible before the end of the ramp to get up to the speed of the moving traffic, sometimes if traffic is light I could shift through all the gears by 2000 rpm and still hit the end of the ramp at 50-60 depending upon the design of the on ramp. I think that even after 25,000 miles in this car, and many more besides in some of the others (although no where near 50 or even the 130 years of my namesake, a fictional character who's over 180 years old)

However if one could carry sufficient speed into the on ramp and accelerate at the appropriate pace to not bog down traffic either on the ramp or on the road would be beneficial to everyone, but it would also allow me to have to shift down less if they would just take the on ramp a little faster, but anyhow I can't control the others so oh well.

Despite the spread in the data which I'm not convinced is the car as much as it was the inaccuracy of the refilling process at least somewhat, the car has always done poorer in the winter, and maybe I'm not as vigilant on the tire pressures when its so cold, but before I took care of the brakes and a few other faults the wheels felt really bad when I had aired the tires up a bit higher than usual (I think the door placard calls for 32psig each, but I usually kept them at 35 instead. Maybe I could try 40psi, but because moist air is already unstable its difficult to predict how well they will hold the extra pressure.

[MGB=MPG]

there is a method on ramps .. many methods
one method
when one turns in to the ramp just idle along , forgetting all behind, until all the sluggards in front of you are pretty much clear and gone [ this is a judgment when to to apply power, quite variable] ,

hesitation at ramp root

then power up to merge

lots depends on the entry to ramp speed traffic density et al

one needs to learn ones equipment and shift points , *i think* the advices is [pending link to methodology description] in the lower gears to run it up on to higher RPM's higher in the power band, then when in the big cog [ top gear]apply steady state FE application to top end.. i like to run out to 3200-4200 anyway.. but thats my motor..


a guess .. a speculation ..run 1st gear to max torque +10% shift [ moderate application].. 2nd to peak torque +10 repeat to TOP COG then apply steady state FE application to max.. cruise..

if one had an instantaneous FE calculator it would help .. however NA for my equipment .. i go by feel smell and sound based on 20K hours of pedal time

[Hubert Farnsworth]

I added an air dam made from a piece of rubber skirting board, and it does seem to have consistently helped to bring my mileage back above 35mpg, the last 8 fill ups the average has been right around 38, with tanks oscillating between 37 and 39.9 mpg, or just lower than the absolute highest I'd ever gotten before, however that may have been with a failed alternator which wasn't creating enough load to keep the car running). I however still have yet to find a bag of zip ties to try and reseal the central section of the factory three piece undertray. I believe that this had gotten tampered with when they were trying to change the oil filter and or the oil itself. The exhaust manifold is quite tightly wrapped around the filter on this car, perhaps the previous owner had headers installed of the standard exhaust manifold after it rusted away/broke.

Some of the mileage improvement is down to having the tires inflated around 40 psig (4 psig less than sidewall maximum), another portion is attributable to the air dam deflecting the air from going beneath the car and creating drag on the undertray and undercarriage, and yet another portion may be attributed to not using the cruise control and trying to maintain an engine speed somewhere near 3000 rpm in 5th with as light a throttle application as I can get away with, however it is difficult as it already feels as if the throttle is on the knife's edge at this point even at that speed, and feels barely depressed, not sure exactly what % the throttle is actually open. A hair too much pressure and it begins to accelerate, a hair too little such as up the hill and I let the speed fall while trying to hold the pedal constant, but backing off slightly on the down hill so the vehicle speed does not increase too much.