davidspalding

Woah, there.

I'm calling . The K24A2 is a high compression engine, requiring a fuel with greater resistance to predetonation,... Honda recommends 91 or better octane for this very reason, it's right there in the manual, not to mention the inside fuel door sticker as well. (A little goes a long way.)

Using lower octane will probably set the anti-knock sensor tripping regularly, causing adjustments which could result in incomplete combustion of the fuel. You may not see a change in mileage (but I did when I tested the theory), but you will not be taking the best care of the engine. I looked up if the Car Talk hosts ever talk about this issue, and on one occasion they asserted that using lower grade gas in a high compression engine will probably leave greater deposits inside the cylinder, and could wreck the catalytic converter. That doesn't outweigh the $50 you save at the pump per year in my view, particularly if you get paranoid and use fuel cleaner additives every few thousand miles.

Can I stop holding my breath now?

jlukja

Good luck with that. Let us know how it goes. You'll have to outdo sauceman who once got 750 miles on one tank (ie. at least 43.8mpg).

https://acurazine.com/forums/showthr...b#post10652742

kewlliljethro

lots of good info here! i've been easing on my driving habits, mainly takin highway w/e i can and minimal use of brakes and maintained about ~25pmg with 70city/30highway. i posted this on the other forum but didnt get an answer yet

"I know this has been covered many times, but how do these mods affect MPG (if driving habits stay the same) and do they have any other effects on longevity of the TSX or other performacne factors?

1. Intake (thinking CT icebox here, supposedly more air= better fuel combustion= better mpg?)
2. Pulleys (thinking UR, more torque at lower RPMS, less stress on engine= better mpg?)
3. Reflash (better power at whole RPM range, possibly better mpg?)

tell me if I'm wrong in any of these."

of course i know the parts might not pay back for themselves if they do increase mpg, but i'd like an efficient car to drive. i'm already purchasing some 18lb wheels soon

jlukja

I guess I would agree with your list but I would put the reflash first, then the intake, and the pulleys last. I think lightweight pulleys definitely help accelleration because of their lower rotational mass. However, the best mpg is to be had at a steady cruise, not accelerating, at which point the mods that have the most effect are the ones that reduce wind resistance (lowering), reduce rolling resistance (tires), improve/optimize breathing (intake, header), and maximize HP per RPM (reflash).

mrgold35

Parts and labor would range between $800-$1200. Even if you increased your combined mpgs from 25 to 27; it would take between 70,000-100,000 miles to break even:

70,000 miles / 25 mpg = 2,800 gallons X $4 per gallon = $11,200
70,000 miles / 27 mpg = 2,592.6 gallons X $4 per gallon = $10,370.40
$11,200 - $10,370.40 = $829.60 saved

100,000 miles / 25 mpg = 4,000 gallons X $4 per gallon = $16,000
100,000 miles / 27 mpg = 3,703.7 gallons X $4 per gallon = $14,814.80
$16,000 - $14,814.80 = $1,185.20 saved

I've always did performance parts to increase performance. It is just icing on top of the cake if I get extra mpgs.

redpoint

I get it; the TSX has a little higher compression (10:1) and has a few more revs than average (7000). My motorcycle has a 12:1 compression ratio and redlines at 14,500 RPM, and Honda suggests I use 86 pump octane.

The manual is the first thing I read before putting fuel in my car, and I ran premium fuel (92 octane) for the first 2 months. In said manual, it says to use 91 octane for "best performance". What it does not say is to use 91 octane for better fuel economy, or to be kinder to the engine or emission system. It goes on to say that using lower than 87 octane can cause engine damage. The implication is that using 87 octane does not cause engine damage.

My personal experience in the TSX was poor performance for the first tank of 87 octane that I ran, and all of the tanks after that had excellent performance and slightly better fuel economy. It will save me roughly $70 per year and I don't have to be angry at myself knowing that I'm supporting the scam of charging more for "premium" fuel.

I have never heard of lower octane fuel being the cause of "deposits" or incomplete combustion, but I have heard of high octane fuel doing this. People that run a higher octane than required in their motorcycle often report a gasoline smell coming from their exhaust. Using a lower octane usually resolves the issue.

Pulleys are the only thing that have potential to save fuel, but it would be so small as to be imperceptible. My estimate would be 1% or less in fuel savings.

Intake and reflash will only improve performance. The performance cams that are engaged when the VTEC is active are not designed for efficiency, but instead power. Think about it, if the cams were both more efficient and more powerful, Honda would use them all the time instead of just when you put the hammer down.

The only thing I can think of that would increase fuel efficiency and power at the same time is the addition of a turbo and a re-gearing. I don't see many on here that have added a turbo to their first-gen TSX, so it must be difficult and expensive.

Actually, the "pulse and glide" method of driving is far more efficient than holding a steady speed at cruise. This method is really only practical on a manual transmission. The reason that accelerating and then coasting is more efficient is that engines make the most power per amount of fuel used when operating at around 80% throttle. Highway cruising using around a 20% throttle opening, so this is very inefficient. The problem with pulse and glide is that it is impractical and even dangerous when done in traffic.

davidspalding

Hello...! People using a different octane than that recommended for the engine smell something funny ... and switching to the recommended fuel resolves the problem. QED. End of line. I rest my case.

[1] I hadn't heard of it either until I stumbled upon the Car Talk guys mentioning it a few years ago. (shrug)

"Pulse and glide...." Hrm. Sounds like something I'd hear in the Relationships forum.

I'll get my coat....

tnieh

^+1

all the money you spend on parts isn't going to save you money for gas unless you're driving for a long time. If you want to get good mpg, just accelerate like a grandma and drive conservatively.

caseman

New (used) TSX owner here. I have been driving an '04 Honda Accord with the I4 for the last 5 years and just picked up an '06 TSX with the tech pkg. Also new to forums and I am an old man - which means I am slow. (driving and typing)
I researched this and talked to mechanics, owners. Answers seem 50/50 which lines up to with what I get from the forum. My plan is to run 87 for awhile with an occasional OReilly's Octane Booster added every fourth or fifth tank. Supposedly it doesn't have any alcohol. The price difference for gas here is at least .50 per gal. I drive a lot in town and on the highway for my work. I have only burned one tank of gas in a week and am averaging between 25 and 26 mpg. I always want better. What I am curious about is more detail on how the ECU works?

edt920

sighh i only get 21 guys :[

edt920

and i really dont know why :[

davidspalding

Try 91 octane or better for a while and check your mileage.

Congrats on the purchase, the '06 is a great model year. And probably a lot more fun than that old American I4 powered sedan.

DuckDodgers

Back to basics...what records did you get with the car?

1) At 127k, the spark plugs are done, if they haven't been changed, change them...if you don't know, at least inspect them.

2) Change your air filter no later than every 15k.

3) Synthetic 5w30 will marginally improve mileage over dino juice.

4) Keep tires properly inflated.

5) Remove extra weight from the car (think about it, an extra 30lbs in a TSX is adding almost 1% to the weight of the car and reducing performance in a similar manner).

6) Run some fuel system cleaner through your system, I recommend Techron. Do it on the next tank of gas...skip a tank...do it again...unless you have evidence of regular use by previous owner.

7) Cruise control reduces mileage because it doesn't adapt to small road changes. When you drive, a slight lose of speed on uphills and a gaining of speed on downhills will show nice bumps in MPG. Use the instant MPG display to figure how to drive more conservatively.

kewlliljethro

whew this thread has a lotta good stuff! imma have to read through it all again when i have time

well an update on what I've done so far after lots of googling and researching. Just doing basic maintenance since I don't exactly know what the previous owner has done for this TSX:

(+) = theoretically helps mpg

(-) = maintenance

+changed spark plugs (here's a picture of the old ones)



^sorry if pictures aren't clear, iphone photography

+switched to Mobil 1 0W30 with Pureone filter, I know mobil 1 is a groupIII oil, but I think it's still an improvement over dino. Will use Amsoil in 7,500 miles

-drained/refilled ATF fluid 4x and had ATF filter changed

-drained brake fluid, refilled, then bled from each caliper (brake fluid was black previously, now amber)

-Power steering recall done, I think they changed the power steering fluid lol

-changed cabin filter

+removed resonator, but didn't put a icebox or horn thing in yet, it's just a hole atm

+tire pressures always at 32psi

+?detailed the car to make it look good. There's a theory that detailing and cleaning all the junk off your exterior would improve MPG a bit due to better aerodynamics, but I highly doubt it. If anything, it'd be a very minimal improvement I'd imagine.

Plans:

+set of RPF1s 18x9 +35. Shaving off 5lbs per wheel should help some

+comptech icebox from Heeltoe. I'm still unsure of the cold air vs hot air impact on fuel economy, since some claim that the ECU will use more fuel due to the denser cold air, but I think if driving habits stay the same, fuel economy will improve with the better airflow, regardless of its temperature?

+UR pulleys from Heeltoe. maybe get a new battery along with this.

+reflash maybe?

? I read about the seafoam and other additives, like the fuel cleaners. Lots of debate over these... what do you guys think about it? The TSX came with 127k so it'd be reasonable to do it, but sometimes hear horror stories or some say seafoam doesn't really do anything. I just changed my spark plugs also =\

-Mugen grill and Rep Euro-R lip!

deepen03

What I've done..

-drained/refilled ATF fluid 3x

-drained brake fluid, refilled, then bled from each caliper (brake fluid was black previously, now amber)

-Power steering recall done last June

-changed cabin filter 10K miles ago I think.

+tire pressures always at 32psi

I have 94K miles now, I'm thinking Spark Plugs next..

nj2pa2nc

did that-no difference for me except spending more money. Had the car serviced 2 weeks ago-It soon will be time for replacing the rear brakes.

psteng19

This is false. An engine is most efficient at WOT.
Personally, I give it 80-100% and go through the gears quickly to get up to traffic speed, making sure I shift at ~3K.

Azzmo

Though I've only had it three weeks, I'm getting ~24.5 MPG with frequent 5 minute drives and cold weather.


When was the last alignment, as of July when you posted this? Properly aligned tires are probably worth a few MPG just for the efficiency.

redpoint

Almost accurate. At WOT the ECU goes open loop and uses a rich fuel map which results in an A/F ratio less than stoichiometric.

I have been using an 85% engine load which is a brisk acceleration, but I also short shift to keep the revs low. I shift at about 2,500 RPM and will cruise in 6th gear at 30mph (approx 1000RPM).

My stop and go gridlocked traffic MPG have improved to nearly the same as my highway MPG. I'm now averaging 30mpg no matter what, although the snow yesterday quickly ate away at that. I estimate the snow cut mpgs by 1/3.

Really wish I had a taller top gear!

TSXPROdriver777

I know this thread is old but i would like to put some insight here for others if they come upon this thread. My previous car was a well modified G35 pushing 285 whp with full bolt ons on a stock block NA power. Now i even had a 5 map tune which were (Race, Daily Driving, Fuel Conservative (which i left on majority of the time), Kill Switch, and Valet mode.) Even when i had it on Fuel Conservative i can tell how dramatically my mpg dropped from all of the power adders i put on. The reason being is any time you add air going thru your engine and change the F/A (fuel/Air) ratio it will lower your gas mileage.... so in fact adding headers, exhaust, CAI would most likely depreciate your mpg. Now if you get a true dual exhaust system and that's it... that might help your mpg a little due to the true dual getting rid of the air/gases faster thru both exhaust pipes rather than one single pipe. Now sending more air thru your engine would change the F/A and the ECU would adjust and your mpg would suffer but would have the enjoyment of more power. Just a little info i thought i would share.

TSXPROdriver777

The best mod for fuel efficient would probably be a drop in K and N filter. Power adders will not help your gas mileage... nope sorry you sacrifice the mpg for the pleasure of speed lol.

redpoint

Your previous post mentioned how adding air to the engine would lower fuel efficiency (which is correct), and this post contradicts it.

Adding a foam air filter might give the slightest power boost at full throttle, but it will do nothing to improve fuel economy, and it will come at the cost of allowing more dirt through the engine.

Air is restricted to the engine with the throttle. In fact, that is the only purpose of the throttle pedal; to restrict air to the engine. The computer then injects fuel in proportion to the amount of air you let into the engine. The only time an air filter can potentially restrict air to the engine is when the throttle is wide open. At all other times, the throttle is restricting air.

The best way to improve fuel economy in the TSX is to drive efficiently. This is boring to most people, because they like to buy things and modify their car. It's a nice distraction from modifying yourself, which doesn't cost a thing.

For the TSX, the cheapest mod you could perform to improve fuel economy would be the final gear ratio. Our cars have extremely short gearing which makes the RPM too high for efficiency. WIth some taller gearing, the RPMs would drop, efficiency would improve, and acceleration would suffer.

Acura should have left the gearing as it is, with the exception of the 6th gear. It's completely useless as a gear on a racetrack (what track could you actually top out 5th gear on), and equally worthless on the freeway where it's screaming at 3,000 RPM just to do 60 MPH.

TSXPROdriver777

Yes... I agree lol. I tried to delete the post afterwards... for some reason there is speculation that the K and N does in fact help your gas mileage. I would have to disagree though because like I posted above any time u add more air into the engine it will most likely decline your mpg since you would be sending more fuel with it unless you get a conservative tune. I didn't see an option where I could delete my post lol. I guess since its my first few posts I don't have that option. My corrected post would have been... The K and N filter would be a good attribute that wouldn't effect your mpg much if at all and it is a good mod since it has a million mile warranty and you don't have to replace the cheap air filter so much.

Yes driving efficiently is the best way to save gas, and I agree running a lower gear would help since the rpms would be lower while driving.

TSXPROdriver777

*Again I couldnt' find the edit option so I'm posting below lol* In our G35's these were the available gears we could swap. 3.3, 3.53, 3.69 which I had, 3.9, and higher. The lower 3.3 gear gave the best mpg rating. When I upgraded from a 3.53 to a 3.69 for more better pull at starts I even saw my mpg lower, but speed and performance will always be more fun than a high rating gas saver lol.