So I have a 2004 GS430.... I have maintained approx 21.9 mpg per the tracker on the car n all of the sudden I am now avg 19.0. Nothing has changed same drive daily, n have even tried babying her to improve it of recent and nothing. It was all of the sudden not like it slowly started dropping. Have ran thru approx 40k miles at 21.9 avg and now last 5k miles approx it dropped to 19.0.

Anything I can try myself?

Recommended any good cleaners for the MAF, plugs, etc?

Open to all suggestions, and all services have been done and are up to date.....

Thx,
Whytry

 

tune up. check your spark plugs, oil, throttle body, MAF sensor, etc.

 

19 MPG is still a decent average. I tend to get 18 now. but do check your basic such as spark plugs, TB and MAF.

 

Did you buy your gasoline form the same place? That can absolutely affect your mileage.

A basic tune up will certainly help your fuel economy like those before me have said. Cleaning the injectors could definitely help as well too. Try an STP complete fuel system cleaner and see if that helps at all.

 

have to agree with this one.

using different gas does change MPG

 

Typically normal. Dont be alarmed.

 

tire pressure??

 

Yea tire pressure and gas brand can definately affect mileage. I would recommend to seafoam your car too to clean everything. I did it and had no problems but there is an argument on this.

 

Get gas at relatively same places everytime. I live near Sacramento, and travel to San Jose weekly, so I typically get gas from the same stations all the time in both places.

I know some are saying me at 19mpg is still good, but when I'm used to almost 22mpg, and nothing has changed, it does cause concern. When I drive as much as I do, that extra 3 mpg is almost another 50 miles... which to me is alot....

On stock 17's tire pressure should be 32psi correct? I am at 32 all around. I run the STP fuel system cleaner in the car now every 3-5k miles, and I have never done the sea foam thing as I have read about it before and read the controversy.... But I'm open to it. I know I drive alot more than the normal so doing everything I can to maintain my GS is very important to me.

Are there ways to clean the injectors myself, better than like the STP fuel additive? Like I said I'm open to all suggestions...

On a typical fill up and drive to the Bay Area I used to avg 24.6 on that drive without much traffic on 50/80/680/280 freeways and last couple trips it is 20.4... Same drive, same drive time, just did it this AM filled up the car n got on the road....

 

You get good mpg. I drive from elk grove to san jose at least once a month and i always get 20mpg. I noticed switching to shells is a bit better on milage.

 

Have you changed how long the car idles in the morning?

 

cleaning maf and tb and seafoam may or may not help
i did seafoam, techron in few tanks, clean tb, maf, changed fuel filter and no change in mpg
did all this because poor city milage (12-15mpg) but probably because i do drive very short distance
highway was always 26-28mpg

 

check brakes maybe seized caliper that will lower mpg

 

I don't get as good as I did recently. That's what made me start trying to figure something out.

 

Nope still the same as always and always in the garage