Lexo11

Just recently I replaced my spark plugs, cleaned my throttle body and mass air flow sensor. I cleaned

both with its recommended cleaner. After that, for a few days the vehicle was acting up in terms of the

rpm was jumping up and down when i was coming to a stop. It was also idling high most of the time

when the engine was on and on park. After a few days the car settled in and operates fine now.

However, now when i check the avg mpg I'm getting about 20-21 city and highway. This doesn't add

up. Has anyone else had this happen? any suggestions?

alredxiii

iTrader: (13)

First you don't specify what year and model 350 430 460 300 also what were you getting before?

Lexo11

The vehicle is a 2007 lexus gs350. Before I was getting about the same mpg give or take.

gr8fulRed

my "in town" driving is yielding about 17.2 mpg.....and I drive like an old lady...meaning VERY easy on the pedal. Seems low to me...but i've only owned the car since January so not sure if this is normal or not. It's an 09' RWD GS 350. The time I did have it on the HWY for nearly a full tank...it was upper 20's..like 28mpg or so. Quite a difference.

Curious..how did you clean your throttle body?

alredxiii

iTrader: (13)

I am getting between 20 & 21 hwy and city on my 08 gs 460.Drove it from Florida and hwy at around 80 mph was getting between 26 & 27.The 8 speed tranny helps cruises at 2k rpm at 78 mph.

Lexo11

All you need is a clean rag and tb cleaner. Spray the tb on the rag or tb and firmly clean it depending how dirty the tb is. Try removing the tb so you can clean the front and back.

Steve2424

If you feel this is too high, I suggest you try driving in NYC lol. I average about 14-16 in city driving and anywhere from 25-28 on highway driving. I have an '08 350awd with 60K miles so I am definitely due for new spark plugs and a TB clean which I am going to have done at my upcoming oil change.
I read within a couple threads that after cleaning the throttle body the car acts "funny" for a day or so, but then returns to normal.