Mpg gauge on an lexus 2001 IS300 improper reading

the fuel sender unit needs replacing as is reading lower than what is actually in tank from whay you've said so far, if your basing your MPG on the gauge reading it will be way out , best way to check MPG fill tank, drive for say 50 miles,, refill tank and see how much you have replaced, that will be your MPG

more MPG, now that is a dream,

No engine size stated, (mine is 3.8L)

there is one method,

put a raw egg under the right foot, and never allow it to leak .

The MPG (turned engine, brakes not dragging)

is 100% related to ,car weight, and your happy right foot.

less happy, more MPG. (i promise)

there is no free lunch in Physics, heavy cars suck fuel.

NO the chip deal.

1: hack in to the PCM. ( google for 3 days, you might find this.

2: then shut down closed loop ops (very illegal) but my answers are pure physics and ECU tuning.

3: then set the AFR to 13.5:1 full time (Dyno tuned.) $$$$$

no free lunch on any Dyno either.



4: now car is gutless and will not accel. fast and will be a lean burn

engine. The engine makes best MPG that is not the same Air fuel ratio

of the legal 14.7: 1 ratio. (EPA) called Stoch, clean burn.

5: defeat enrich mode. next.



if you really want to learn, read this book, sure will cost you $15

but its all there. every steps.

Greg Banish

http://www.amazon.com/Engine-Management-Advance-Greg-Banish-ebook/dp/B009K4B66O/ref=sr_1_1_bnp_1_kin?ie=UTF8&qid=1394636425&sr=8-1&keywords=EFI+tuning



and last , here is one car that gets 84mpg

note the extremes.

http://www.youtube.com/watch?v=9XUKOUbp_PA&feature=player_detailpage#t=0s





not that most CHIP sellers , lie about HP gains. 20% and all that.

and if they SELL MPG chips, more lies. get the promise in writting

and with full refund , if it fails... they wont do that.



then there are the guys that sell you a $100 , 3cent resistor

that replaces the IAT.

the closed loop system will bypass that, SEE the longterm

fuel trim , hide your fibbing IAT? sure.

if you fib enough, say go too hot?

the Closed loop will end or the the ECU will goto limphome.

if it goes to limphome, MPG goes HORRIBLE.

if not the hot (fibbing) IAT sensor will cause lean burning.

a good way to burn exhaust valves and makes tons of NOX pollution.

(you will fail the smog test)

and the new ECU on your car (i have an 08 JK)

will throw DTCs for too lean. all day long.

so what is the value in that? i dont know.

so DIY

buy your custom ECU and programming.

are you running fuel sucking A/T trannY?



i designed my own MPG gauge. (obd2)

my JeepsDASH MPG,(stock) is long run average. useless to me.

My gauge is real time. all the time. averaged for about 3 seconds.

if im a good boy (retired tech) i get 25mpg.

(driving normal its 19mpg) 3.8L V8, 60k miles.



get rid of weight

get rid of A/T

buy a guage and learn how to drive all over again.

lots of coasting , avoiding the usage of brakes (safely)

and slow Acceleration. (

Stay in closed loop, (my gage has that) and mPG just happens.

fix dragging brakes, on car, , bad caliper guides?



on the stock gauge you must push reset over and over.

to get real time readings, that are meaning full. a pain.





and first learn what a CHIP is ( it means nada)

Make them tell you what it really is, or just pass.

If you work hard for the money. that is.

quad posted in 17 minutes flat. now that is impatient.
and , worse no MPG stated. or liters /100km.???
nor if its city or highway. MPG.
nor engine option, (mines a 2.5L tuned to max)

btw , my 2.5L H25 gets 19 mpg best case.
mine has a MPG gauge. i designed,
the engine is too big and car too heavy (comprared to gen 1 or gen 2 vitara's) so sucks fuel.
the 2.0L I-4 does better but not by much.

Are you going by the gauge that says fuel economy on the dash, if so try to zero out the gauge or reset it ,this will recalculate the reading.

Could you have missed reconnecting a wire someplace? Possibly a ground

Hmmm. The unit that calculates the fuel is under the back seat base. There are two level sensors under covers on either side. Could be that you have a trapped wire shorting and when you go into reverse the back axle just momentarily jogs the shorted wire. I'd look at the wiring there.

It caused by a faulty sending unit inside the gas tank or your fuel filter and or fuel pump needs replacing.

Good Luck!

You try taking it to the Mechanics, its a problem you might not be able to solve.

This simply could be your AVERAGE mpg symbol. Use the computor button on the RH stalk to change its setting.

Yes it is possible.