Upgrades For Better Mpg?

[John A.S.]

I plan on upgrading a few things to see if I can improve my gas millage and I am wondering if its worth spending about $800-1000. I will put some iridium long lasting spark plugs, performance filter, high grade synthetic oil, and then regulate the air pressure on all tires and upgrade the ignition system further with an Ignition Amplifier, Ignition Capacitor, and a Voltage Regulator. I guesstimate that would allow me to squeeze 1-2mpg. Does anyone have some suggestions?

[Alexander the o.k.]

I'm thinking a lighter foot would have at least as much effect. Mind you I don't 'hypermile', but I think there's a happy medium. E.G. - try to coast to lights and avoid the red, easy take offs, etc.

It used to be that when I did that, there would always be some leadfooted hothead 1 foot from my rear bumper. With gas at 4.25 I see lots more people driving gently, and much less of that. They are now doing it too.

Sounds you've got most bases covered on the hardware. I'd also vac out / change the air filter every couple thousand.

Have an emissions test done.

That will tell you a lot.

[monstromarino]

I plan on upgrading a few things to see if I can improve my gas millage and I am wondering if its worth spending about $800-1000. I will put some iridium long lasting spark plugs, performance filter, high grade synthetic oil, and then regulate the air pressure on all tires and upgrade the ignition system further with an Ignition Amplifier, Ignition Capacitor, and a Voltage Regulator. I guesstimate that would allow me to squeeze 1-2mpg. Does anyone have some suggestions?

[monstromarino]

I plan on upgrading a few things to see if I can improve my gas millage and I am wondering if its worth spending about $800-1000. I will put some iridium long lasting spark plugs, performance filter, high grade synthetic oil, and then regulate the air pressure on all tires and upgrade the ignition system further with an Ignition Amplifier, Ignition Capacitor, and a Voltage Regulator. I guesstimate that would allow me to squeeze 1-2mpg. Does anyone have some suggestions?

put a K&N air filter and a tornado air great results and a lot cheaper

.

[Step Hen]

Maintaining your vehicle properly would save you the most fuel. Check and change your plugs, filters, etc when necessary. Spending $800-$1000 for a possible 1-2 mpg gain is not economically feasible.

And @ monstro: people may take you seriously about the tornado! :P

[nc211]

swapping out parts like that won't give you much in return, and certainly don't mess with that damn tornado thing, as it's been known to throw codes in these cars. Save your money on the parts and instead invest your time on some servicing. You'll want to clean the throttle body (search for proceedure), you'll want to run some seafoam through the intake (search for proceedure), you'll want to cycle a cup of seafoam in with your oil at idle for about 20 minutes before changing it (search for proceedure), you'll want to put in new plugs AFTER the seafoam, you'll want your air filter clean, you'll want synthetic oil and synthetic rear differential oil. You'll want to understand how do "drain n' fill" the transmission fluid (search for proceedure), you'll want to detail the car up to make it smooth as glass. And then, you'll want to just kick back and cruise. The V8 is great, and will treat you and your wallet well. But you get addicted to that V8 kick under your foot, and your foot will soon find your butt and kick it everytime you fill it up!

The debate on the KN air filter is eitherway. Some like it, some don't and say it allows too much dirt into the engine. Honestly, oem set up seems to work great. I did all of these things to my old LS, and was still clearing 25mpg+ at 80mph, and 18mpg around town. But, I have a heavy foot and addictive personality, so city mpg was only that good when my wife was in the car. When she wasn't...i'd say probably 12-13mpg around town. I LOVE V8 ENGINES!

[eatingupblacktop]

Use prem fuel; keep your throttle body, plugs, filters, and injectors clean; keep your fluids fresh; tires pumped; windows closed (if you can) or a/c off (if you can); leadfoot off (if you can - not like NC); car body clean (dirt drags); trunk empty (weight drags); car moving (0 mph = 0 mpg); and smile while you're driving - that's always good for an extra 2 mpg.

[JENunnez]

That right foot is the most important, be smooth,smooth,smooth on that throttle. Then again every once in a while my foot gets dumb and it turns into a 15 lb. wieght. Then it's back to reality. Still, I.....Like it !

B)

[AZ Mike]

The debate on the KN air filter is eitherway. Some like it, some don't and say it allows too much dirt into the engine. Honestly, oem set up seems to work great. I did all of these things to my old LS, and was still clearing 25mpg+ at 80mph, and 18mpg around town. But, I have a heavy foot and addictive personality, so city mpg was only that good when my wife was in the car. When she wasn't...i'd say probably 12-13mpg around town. I LOVE V8 ENGINES!

I have a gently used '99 LS400 with just over 60K miles. Everything is stock. I just did the 60K service myself and replaced all necessary items with OEM parts. I consistently get 18-19 in town and 28 on the interstate. I actually achieve a little better if I am gentle on the "go" pedal as mentioned.

With regard to the K&N......I have seen these "dirt" arguments for years. I have had the K&N FIPK on my '94 Grand Cherokee for nearly 10 years. This is an american made 4X4 with 170K miles; engine is clean as a whistle and it runs perfectly. So, from my experience, I have to cry "BS" at the dirt argument. Maybe it does or does not pass along slightly more dirt than the OEM filter, but if it does, it is negligible and in no way negatively impacts the vehicle. And on an air restrictive stock setup like on the Grand Cherokee, it provides demonstrably better throttle response and a big increase in hp (25 according to K&N dynos). That being said, you get much more bang for the buck with aftermarket mods on vehicles that do not leave the assembly line optimized. I have a Honda S2000 that is so well tuned out of the factory that mods give negligible benefit. I haven't really investigaged mods on the Lexus, but my assumption is that it is much more like the S2000 than the Grand Cherokee with respect to mods. The air intake does not appear restrictive, so I think minimal benefit would be obtained by using the K&N. Just my 2 cents.

[John A.S.]

You know I was thinking the other day of an idea, cold air makes for more efficient combustion and hp and there are air cold air intake mods for this. But if you could somehow direct the cold air coming inside the car that cools use humans down and share it with the engine, wouldn't this make a significant mpg or hp improvement? Or maybe even build a simple ac unit into the trunk and have a pipe direct its cool air to the engine.

[DrJfrmLA]

Step Hen made a good point. You can spend a LOT of money for marginal or no increases in fuel economy. If you spent $500 to get 1 mpg, the math on that payback is never. A light right foot is the ticket--then the fuzzy logic in the transmission controller will shift sooner, you'll get in top gear quicker, and your gas gauge will move slower. More than one professional driver (not racer, livery) has suggested driving as though there were a raw egg between your shoe and the accelerator pedal. It doesn't make for exciting stop light Grans Prix, but I'm averaging 21 in my LS in mixed driving and over 22 in my MB S430 in the same conditions without hypermiling but just taking things a bit more gently. Slowing your interstate speed is also a free ticket for more mileage. I still cruise between 75 and 80, but my former 85+ cost an additional 10% mileage penalty or more. All you young drivers would probably have a sharp stick in your eye rather than slow down, but that's the ironclad secret to better gas mileage. You can scoot and pay the penalty or not; it's your gas bill and your business. Carpe diem.

[John A.S.]

True lighter foot=$ and that was accidentally proven on a myth busters show some time ago when they where showing how the draft behind a semi could boost your mpg 40% but as the test driver got really close in the end instead of saving more gas as he got closer to the semi he actually did worse mpg because his nerves had him beating the pedal.

[SRK]

Driving style is easily the biggest factor. Drive gently, ease the gas pedal, time lights so you don't have to stop. Think of the brakes as wasting fuel, which they do, as every time you use them you are extracting energy from the vehicle achieved with gasoline.

The fuel trim on these engines is as good as one can get it with the technology of the day. You'll never improve the ignition system. It doesn't misfire now does it?

The K&N filter is no big deal. Buy one if it makes you feel better. But if you over-oil it and contaminate the mass air flow sensor, well, there goes any mileage improvement. And air restriction is simply not an issue if you drive at less than full throttle. Idle and low rpm airflow through the filter is quite miniscule compared to that at full throttle, where a restriction MIGHT show up. (and 25 hp improvements are a bunch of crap, let alone that the only point at which an improvement like that could be measured is FULL throttle.)

Narrow tires at high pressure, synth oil, yep they'll help.

But one full throttle blast up an on ramp will negate any improvements from those two.

Drive less.

[qha_vn]

there are always many ways out to face with increase gas cost, instead of wondering if a 500 bucks could save some, we may think of using the car less, get a part time job, ask boss for fuel incentive or even change job with better pay. sorry if this is kind of off topic

[Bali26]

I was doing all this stuff and still getting 13mpg city. Then i changed my thermostat for about $20. (Needle was below half mark)

Now I get 19mpg.

[Alexander the o.k.]

bali,

could you expound on this a bit?

what is the connection?

[jcrome04]

Yeah I'd like to hear about the thermostat too.

I got a K&N about 1-2k miles ago and everything was dandy. Then I noticed a drop in my MPG. Pulled out the K&N there was a TON of dust behind the filter :( and there was no bright red coloring left AND it was covered in debris and bugs and crap. I went back to my OEM filter and everything is right as rain.

I've never had a problem with a K&N until now, and frankly, I feel sorry for letting all that dirt into my poor lil 1UZFE. $60 mistake. Until Amsoil produces an EEA or whatever for my car I'm sticking to OEM air filters.

[HRP]

Air resistance cuts your mpg also. Suggest you really clean and polish your car until it is smooth as a baby's butt. Then apply a good sealant and give it wash and a quick detail frequently. Also, the car has less resistance and gets better milage with the windows up and the a/c on than it does with the a/c off and the windows down and sun roof open. Talk to your tire people. Most people run their tire pressure at the 'factory recommended' level. Learn to read the codes on your tires and run them at a higher pressure and watch the wear pattern. Wear at the edges (both inner and outer) indicates a too low pressure; wear at the tread crown indicates too high a pressure. I run my 2002 LS430's Michelin A/S Sport Pilots at 38 lbs all around. good handling and even tire wear. Also have them balanced and rotated every 5k and a 4 wheel alignment every 5k. Most state Highway Patrol cars run at 40 lbs. "Google it!" Check the car for "stuff". It is amazing how much junk accumulates in the pockets, compartments, under the seats and in the trunk - unnecessary weight to spend mpg for. And, as mentioned earlier, drive at least 1/4th mile ahead, preferably 1/2. If you know that light is going to be red when you get there, take your foot off the gas now. And drive with one foot. Those who drive with one foot on the brake and one on the accelerator wear out their brakes quicker and also get really lousy milage (and are a pain to drive behind). When you can, in highway driving, set the cruise control and avoid weaving in and out of traffic. Before you purchase a K&N or new plugs, check them out with some on-line research. I have a K&N in one of my cars (gift of my son) and I maintain it regularly and I can't tell a lick of difference. There was a thread about all of these upgrades posted on the Buick Reatta Forum recently with some excellent references, especially regarding air filters, oil filters, and synthetic oils, etc. You might search that forum (http://forums.aaca.org/ubbthreads.php/ubb/postlist/Board/3/page/1) Also consider that you are planning to spend $500 or the equivalent of 100 to 125 gallons of gas to get a 5 - 10% increase in milage. Do the math based on your annual miles driven and possible cost savings; you might be better off investing those bucks in a cd. Yeah, I know most all of the above is common sense, but common sense ain't "common".

[Bali26]

bali,

could you expound on this a bit?

what is the connection?

Hi,

Thermostat prevents engine coolant from going to the radiator to be cooled until the engine heats up to the right temperature. It is at this point the ECM starts regulating the fuel by listening to the O2 sensors. Before this the engine runs rich (to heat up cat convertors)

So if your thermostat is bad (stuck open usually), engine will never reach proper temperature and your engine will run rich giving you very bad mileage.

[jcrome04]

So if a thermostat isn't broken would it be beneficial at all to get a new one anyways?? Considering the low cost.

[Bali26]

Well its easy to remove the thermostat and check it. At room temperature it should be fully closed. Then if you drop it in boiling water it opens up.

Also if it is stuck open the temp gauge needle will not go past halfway mark like it should.

Also if when the car is in motion the temp needle drops, thats a bad sign too.

Here you go: http://us.lexusownersclub.com/forums/index...showtopic=14708

[SRK]

Hi,

Thermostat prevents engine coolant from going to the radiator to be cooled until the engine heats up to the right temperature. It is at this point the ECM starts regulating the fuel by listening to the O2 sensors. Before this the engine runs rich (to heat up cat convertors)

So if your thermostat is bad (stuck open usually), engine will never reach proper temperature and your engine will run rich giving you very bad mileage.

This is not completely true, but close.

The engine when cold operates in "open loop", meaning no O2 sensor input. As with most cars now, the O2's are heated, so they come on line quickly, and at that point the engine operates in "closed loop" meaning the feedback loop that allows the O2's to trim the mixture. In open loop the ECM uses programmed values and stored long term memory to achieve a relatively accurate fuel ratio, because if it doesn't the car won't meet emissions standards which are also defined for warm-up.

The effect of a cold or broken thermostat is that the engine coolant temperature sensor (different from the coolant gauge sensor) will think the engine is still warming up, and delay the closed loop point, or even prevent it. I don't know specifically how Lexus/Toyota strategies work, but they'll be similar to most.

So yes, the engine will run somewhat rich with a thermostat that doesn't produce proper temperature. Modern engines like to run very hot, compared to those of the 60's and 70's, because it makes for better fuel mileage and lower emissions.

[jcrome04]

Nice. So where can a thermostat be purchased? How much is an OEM one??

I haven't searched TOO hard... but are there any DIYs on flushing the coolant on a 2nd gen???

[Bali26]

This is not completely true

Which part is not true?

[AZ Mike]

(and 25 hp improvements are a bunch of crap, let alone that the only point at which an improvement like that could be measured is FULL throttle.)

Yeah, I'm sure K&N just made up this dyno run (http://www.kandn.com/dynocharts/57-1506_dyno.pdf), as certainly there would be no legal liability in doing so. And of course peak increase will be near full throttle; have you ever seen a dyno improvement where the peak difference is at the lowest RPM? Sure, there are variables, and every vehicle may not have the same exact dyno run. But, I'll accept an actual dyno run by a successful well known company than merely the opinion of a board blogger any day.