Marino2847

Hello all, my 99 Ls400s mpg has dropped to 15 mixed city/highway driving. When I first got the car, it averaged about 17 mixed city/highway driving. When I first cleaned my MAF, my mpg jumped to 28 on the highway and 20 in the city. That only lasted a couple days before it dropped back down to about 17. Then it kept dropping down all the way to 14 mpg. I decided to replace the MAF and it went back up to 17 mpg then began to drop to where its now at 15 mpg. I just replaced the thermostat today and the mpg is still at 15 mpg. I've cleaned the throttle body, replaced spark plugs, fuel filter, coolant, changed oil multiple times, and air filter. The weird thing is that the car runs very well. Acceleration is quick, it idles smoothly, and it has plenty of power. The car also has a Jbrady intake and is on coilovers if that affects anything. Any input is much appreciated, thank you all.

YODAONE

Low MPG question is routine question.

Who has low MPG checklist..or is it already a sticky.?

RA40

iTrader: (6)

There is a bit about poor gas mileage in the main sticky. We can probably append more and similar discussion threads to it.

This is one:
All LS400 owners with bad gas mileage READ THIS! (ECT-coolant temp sensor discussion)