mpg

[AustinTxMR2]

Originally Posted by LordNikon

rear air diffuser

What is a rear air diffuser?

Oh, did you happen to see the price on those spark plugs? $25each!!!

John

[phzoinkMKII]

Holy expensive spark plugs. They had better come with a BJ at that price.

[LordNikon]

I hope this clears things up a bit. I think only the top "rear" section is what I was refering to but the rest is informative if not confuseing.
Diffuser (automotive - Wikipedia, the free encyclopedia)

Yeah, I know $25 per plug is a bit crazy but I want to try them and see how well they work. If I do I will definately post about it.

[AL1222]

my aw11 is getting 28mi per gallon....im gonna replace the 02 sensor this weekend let see if it improves my mpg.

[Teado]

Did you have any luck with the O2 sensor helping your fuel economy?

[Timon]

I actually came to the conclusion I'm getting about 31-32 mpg city. Since I was reading the manual, and it says to fill up at a quarter of a tank (it says that letting it go all the way to empty can cause it to misfire and screw up your cat), that's what I've been doing.
I've been filling up at about 250 miles +/- 20 on the trip meter, and putting in about 8 gallons. This puts me at 31.25 mpg, and varies a lot depending on how I drive. Max I've seen my car get, utilizing all available resources to improve mpg, is 36 city.

[dr3amr2]

Originally Posted by Timon

40 MPG... that is very high. I have done an entire tank of shifting at 2.5k and still can't hit anywhere near the 300 mile/tank mark. This is when waiting until the fuel light comes on.

Other than the coils, do you have any other mods? I have a cold air intake, which I assumed was going to help w/ gas, but I didn't notice much of a difference.

Minus 2 mpg from your coils that puts it at 38, so I'm still about 12 mpg behind you for some reason.

You can increase your MPG by changing your driving style. Shifting @ 2.5K RPM will infact decrease your MPG. You're basically taking your car out out it's most efficient spot on the powerband and loosing all of the mechanical gearing advantage when you're trying to gain speed. You should try shifting around 4-4.5K.

[AustinTxMR2]

Originally Posted by dr3amr2

You should try shifting around 4-4.5K.

How can you think that reving your engine high enough to kick in TVIS is going to improve your MPG?

John

[dr3amr2]

Originally Posted by AustinTxMR2

How can you think that reving your engine high enough to kick in TVIS is going to improve your MPG?

John

I know this isn't a MKII section, but I'm using the available knowledge that I have to help support my claim. The stock MR2 E153 tranny gears are:

1st - 3.23
2nd - 1.91
3rd - 1.25
4th - 0.918
5th - 0.731
Final Drive - 4.28

By doing some basic math you can quickly determine that going from 1st to 2nd gear you're loosing 40.8668% in mechanical efficiency that being output to the wheels. So to make up the difference in the dramatic powerloss, one would usually increase the throttle position to speed up faster and waste gas. They could go from 1/4 throttle in 1st gear to at least 3/4 in 2nd gear to keep the smooth constant acceleration. So you're easily wasting 50% more fuel right there by shifting too early. So its pretty retarded to not take advantage of your gearing and powerband to optimize efficiency to reach a certain speed limit.

The TVIS increase the injectors pulse width when activated and does decrease your MPG but is it enough to make a difference in comparison to my claims? Please explain to me how is the TVIS going to hurt your MPG in comparison to shifting too early and always falling out of the powerband.

BTW - I averaged 29-30 MPG during the winter months with my 94T driving 50% highway and 50% city. I think that's pretty good for a mostly stock car that sees 15PSI pretty often.

Dzuy

[Timon]

Since recalculating (as noted in my previous post), without trying I'm getting 31-32 city, which is usually shifting at about 3k - 3.5k, and occasionally doing higher revs into 4k-5k, opening TVIS.
IMO, it feels like the power band is between 3k and 5k, because this is where most of the get up and go is, not that it doesn't have power all the way up to the red line.
The 4AGE produces it's max torque at 4800 RPMs, which is relative to the 5k feeling.

I agree shifting too soon can decrease mpg, but shifting too late can cause more problems than shifting too early. Also keep in mind time plays a factor too. If you're always shifting early it takes you twice as long to catch up to speed, and therefore takes longer from point A to point B - granted this usually isn't as big of a factor as the shifting itself, but does play a role.

[AustinTxMR2]

Originally Posted by dr3amr2

Please explain to me how is the TVIS going to hurt your MPG in comparison to shifting too early and always falling out of the powerband.
Dzuy

Flogging and jackrabbit starts are KNOWN methods of ruining your MPG. I consider engaging TVIS flogging when you are attempting to obtain decent MPG.
If I can obtain 36 to 38 mpg as an average for 2 different years, something must be said for city driving and shifting at 3200 RPM. These results are not from pick and choose results, this is from recording EVERY tankful and miles obtained from that tankful.

Originally Posted by AustinTxMR2

In 2006, I put 13,500 miles on my Mk1 and averaged 36.12 MGP. I pumped 374 gallons of fuel that year into her.

In 2007, I clocked 16,462 miles and the years average MPG was 38.2

John

[dr3amr2]

Originally Posted by AustinTxMR2

Flogging and jackrabbit starts are KNOWN methods of ruining your MPG. I consider engaging TVIS flogging when you are attempting to obtain decent MPG.
If I can obtain 36 to 38 mpg as an average for 2 different years, something must be said for city driving and shifting at 3200 RPM. These results are not from pick and choose results, this is from recording EVERY tankful and miles obtained from that tankful.


John

Please back up your statement with some real calculations, numbers, or scientific data. I hate it when people just say things like "it is a community knowledge and therefore you are wrong." That's probably the weakest type of argument that anyone can put out to the table. You gave me no explanations at all to why there are any flaws in my claim or any real backup to your claim.

Like whats the % increase of injectors pulse when TVIS is activated and how much MPG will it decrease? When does the TVIS activate? So from the time it activates to 4.5K, how much MPG are you loosing due to that?

BTW getting 36-38 on a 1.6 NA engine is good but shouldn't be something to brag about. It can be replicated by any other well maintained 4AGE powered MK1.

O yeah just to put it out there, my worse ever recorded MPG is 24.44 and that is due to my clutch going out. My average for when I included some racing (auto-x,mountain run,drag) is 26.6 MPG. The average that I gave out earlier is just normal day to day driving with random boosting involve. My total average from EVERY tankful and miles obtained from that tankful is 28 MPG. So does that make you feel any better?

How you ever dynoed your car? If not, i'll just assume it's stock and you're making 115HP to the flywheel. I'm making 240 HP to the wheels on my car. Just for shits and giggles, I'll just do a comparison between these two numbers alone. That means that I'm making about 208.69% more power than you (Hint I'm wasting a lot more gas than you are). My engine is a 2.0L so that means that my engine is 20% bigger than yours (Another hint that I'm still wasting more gas even at idle).
Recap:

*My engine is 20% bigger than yours.
*My power level is at least 208.69% more than you.
*But my gas consumption is 26.31% less than you.
Note I'm taking my TOTAL average of 28 and comparing to your best average of 38.

Here's my dyno to support my claims.


Dzuy
PS - I would love to be proven wrong, because I'm not here to claim that I know everything. Please give me some real supporting evidence that you are right and I am wrong.

[Timon]

Originally Posted by dr3amr2

When does the TVIS activate?

*raises hand a jumps up and down wildly* I know, I know, I know! 4200 RPMs!

[AustinTxMR2]

Originally Posted by dr3amr2

Please back up your statement with some real calculations, numbers, or scientific data.

No.

[dr3amr2]

Originally Posted by Timon

*raises hand a jumps up and down wildly* I know, I know, I know! 4200 RPMs!

Sweet!

[dr3amr2]

Originally Posted by AustinTxMR2

No.

Thanks, now I know who to ignore from now on

[Timon]

Science is all theories until proven effective in the real world through trial and error. In John's (AustinTxMR2) defense, I'd say he does have some pretty good data; however, I'm willing to test your theory, dr3amr2.

Originally Posted by AustinTxMR2

... something must be said for city driving and shifting at 3200 RPM.

Originally Posted by dr3amr2

You can increase your MPG by changing your driving style. Shifting @ 2.5K RPM will infact decrease your MPG. You're basically taking your car out out it's most efficient spot on the powerband and loosing all of the mechanical gearing advantage when you're trying to gain speed. You should try shifting around 4-4.5K.

This unfortunately can't be a perfectly staged test (meaning it will not be identical in every way), but life is not perfectly staged either.

Test 1: Shifting ~3200 RPM, and utilizing other methods of increasing mpg.
Test 2: Shifting ~4500 RPM, and utilizing other methods of increasing mpg.

Both tests will be conducted by topping off the tank, without rounding off the dollar amount.
Resetting the trip meter prior to starting the engine.
Both tests will be performed based on city driving.
Each test will end once the gas tank is at approximately 1/2.

I will record the total amount of fuel used to refill the tank, and divide that by the amount of miles driven.

I would however like a few clarifications prior to the testing.

Test 1:
Any specifics?

Test 2:
1. Am I still to use other methods to increase mpg, such as watching the side lights, coasting in gear (or would you prefer out of gear?), substituting braking with downshifting, etc. ?
2. When coasting to a light and slowing down, but NOT coming to a full stop, what RPM range am I looking to go to as far as the gears? To clarify, if I'm coasting at 30 mph and losing speed approaching a light, in 3rd gear at say 2k RPMs, the light goes green. I can do one of two things, and since I'm following your theory here, I'd like your advice.
a. Do I down shift into second boosting my RPMs into the 3-3.5k range and then continuing up to open TVIS from there?
b. Do I stay in third gear and ride that back up to the point of opening up TVIS?

[dr3amr2]

Hey Timon, I like the way you think. But the only way to do proper testing is to only have one variable. Meaning that you should be doing everything the same between the two test except the shifting points.

My theory that I talked about so far only talks about accelerating up to a set speed limit. So that means that shift between 4-4.5K when trying to get up to speed, other than that you can do what ever you want while coasting or decelerating. Just keep it constant with Test 1.

You should also probably have a baseline comparison. Since you have been shifting at 2.5K you can use the data from that for your baseline comparison with Test 1 and Test 2.

Thats all that I can think of right now, so good luck and have fun on your test!