maliy0204 Posted May 23, 2008 Share Posted May 23, 2008 Hi guys. I have a 2000 Lexus GS 400 with 115k miles. I was reading up on my car and it says that i should be getting around 17 miles per gallon while driving around the city. i seem to get around 11-12. And about 18-19 highway. Which is very disappointing, the only thing i can think of is that i have a catalytic converter problem which makes the "check engine" sign show up. Fixing this problem would increase my mpg back to 17? or is it another problem that i am not aware of? Quote Link to comment Share on other sites More sharing options...
TRD911 Posted May 23, 2008 Share Posted May 23, 2008 Hi guys. I have a 2000 Lexus GS 400 with 115k miles. I was reading up on my car and it says that i should be getting around 17 miles per gallon while driving around the city. i seem to get around 11-12. And about 18-19 highway. Which is very disappointing, the only thing i can think of is that i have a catalytic converter problem which makes the "check engine" sign show up. Fixing this problem would increase my mpg back to 17? or is it another problem that i am not aware of? What is wrong with your converter? Is it clogged, then yes to a decrease in miliage due to that! If it is just not performing then it may effect your fuel air mixture and that would cause what your seeing as well. If you replace your converter I would love to buy your old one from you to make a test pipe so I can take mine off. I would even pay shipping to me and then ship it back to you. I need it to make a test pipe. BP Quote Link to comment Share on other sites More sharing options...
sakataj Posted May 23, 2008 Share Posted May 23, 2008 welcome to the forum.......um.......whats the code readin for the check engine light? thats what u need to find out! brian Quote Link to comment Share on other sites More sharing options...
djspawn00 Posted May 25, 2008 Share Posted May 25, 2008 have your spark plugs been changed? Old/Dirty plugs destroy your mpg... A bad cat probably won't harm your mpg as much but it does harm nature... and i'm guessing you got code po420 for you cats? I think. Quote Link to comment Share on other sites More sharing options...
Future Posted May 27, 2008 Share Posted May 27, 2008 Hi guys. I have a 2000 Lexus GS 400 with 115k miles. I was reading up on my car and it says that i should be getting around 17 miles per gallon while driving around the city. i seem to get around 11-12. And about 18-19 highway. Which is very disappointing, the only thing i can think of is that i have a catalytic converter problem which makes the "check engine" sign show up. Fixing this problem would increase my mpg back to 17? or is it another problem that i am not aware of? Another way to increase your mpg is to clean your MAF sensor and throttle body plate. I heard that works wonders, most likely I'm going to do that next weekend! Quote Link to comment Share on other sites More sharing options...
Future Posted May 30, 2008 Share Posted May 30, 2008 Also, are you what type of gasoline are you using, I notice my mpg improves a lot when i use super versus regular or plus. Quote Link to comment Share on other sites More sharing options...
maliy0204 Posted May 31, 2008 Author Share Posted May 31, 2008 i use 93 gas. always been using it. im not sure what the code is for the check engine sign. thanks for the replies so far guys. Quote Link to comment Share on other sites More sharing options...
djspawn00 Posted May 31, 2008 Share Posted May 31, 2008 I'm in NYC also, you can go to any autozone and have them read the codes for you for FREE. I think something in NY gas has been different though, a lot of my friends, and coworkers along with myself have noticed an increase in MPG these past few weeks... i hope this trend of good gas remains as $4.45 a gallong is making me look for bicycles on craigslist. Quote Link to comment Share on other sites More sharing options...
Future Posted June 2, 2008 Share Posted June 2, 2008 I'm in NYC also, you can go to any autozone and have them read the codes for you for FREE. I think something in NY gas has been different though, a lot of my friends, and coworkers along with myself have noticed an increase in MPG these past few weeks... i hope this trend of good gas remains as $4.45 a gallong is making me look for bicycles on craigslist. You know what, I've been experiencing better mpg than usual over here in NJ - weird...but I'll take it... Quote Link to comment Share on other sites More sharing options...
CarbonGS Posted June 7, 2008 Share Posted June 7, 2008 Hi guys. I have a 2000 Lexus GS 400 with 115k miles. I was reading up on my car and it says that i should be getting around 17 miles per gallon while driving around the city. i seem to get around 11-12. And about 18-19 highway. Which is very disappointing, the only thing i can think of is that i have a catalytic converter problem which makes the "check engine" sign show up. Fixing this problem would increase my mpg back to 17? or is it another problem that i am not aware of? try seafoaming the motor! it does wonders for high mileage cars and is 100% safe http://www.seafoamsales.com/motorTuneUpTechGas.htm Quote Link to comment Share on other sites More sharing options...
sakataj Posted June 11, 2008 Share Posted June 11, 2008 yeah carbon i cannot see u or anyone putting that stuff, safe or not, into a 50k car! i just wouldnt chance what some unknown additive would do! "i will welcome myself back to the forum as im woo hooooooooo im finally unsuspended! hahaha!" brian Quote Link to comment Share on other sites More sharing options...
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