scorpion_x9 Posted December 18, 2003 Report Share Posted December 18, 2003 I'm trying to find the cheapest way out of this, of course. My GF's car is getting extremely terrible gas milage, which is about 150 miles to a 14 gallon tank. It's a Grand Am w/ 3.3L, and this car a NO EGR valve/system of any kind. I hope it's the O2 sensor, becuase it's only $20 . It does idle kinda funny like it's gonna stall if you don't do an idle re-learn, and the throttle plate is adjusted to fix the idle problem, which may be adding to the problem but I don't think that would make that big of a jump becuase it only idles at about 800-900 rpm. But the real question is, what would cause this enormous jump in fuel consumption, and I just need a second opinion? Thanx! Quote Link to comment Share on other sites More sharing options...
patgizz Posted December 18, 2003 Report Share Posted December 18, 2003 i'd guess o2 sensor, alot of times they do not trigger the SES light when they are going bad. Quote Link to comment Share on other sites More sharing options...
Thabulldog Posted December 18, 2003 Report Share Posted December 18, 2003 This may sound stupid.. but what about a gas leak? This happened to 2 of my friends this week alone. They were getting worse and worse gas mileage until they finally smelt gas and looked under the car and found a puddle. Quote Link to comment Share on other sites More sharing options...
Cheesy411 Posted December 19, 2003 Report Share Posted December 19, 2003 Well it happend to me my car got shitty gas milleage on my cutlass I just replaced the tank 90 dollars for the tank i did the rest myself replaced some fuel fittings and wala no more leaky check that out first, my friend owns a Grand am with a 3.3 also he had fuel problems he got his injectors cleaned and it ran fine. I hope i was some help Quote Link to comment Share on other sites More sharing options...
SigEpCutlass Posted December 20, 2003 Report Share Posted December 20, 2003 it's more than likely that your fuel system is dirty. get some fuel injector cleaner and it should help some. Quote Link to comment Share on other sites More sharing options...
phantomFE3 Posted December 20, 2003 Report Share Posted December 20, 2003 check tire pressure, alot of people dont know this but incorrect tire pressure is the #1 cause of gas mileage decreasment Quote Link to comment Share on other sites More sharing options...
rudefyet Posted December 20, 2003 Report Share Posted December 20, 2003 i'd check the plug wires and the vacum lines too Quote Link to comment Share on other sites More sharing options...
SmokesGTP Posted December 20, 2003 Report Share Posted December 20, 2003 Yeah but tire pressure won't decrease it that much. Maybe a mile per gallon if they are really off. I've put a lot of thought into it. I'm tearing my car down over vacation and I'm gonna get to the bottom of my gas mileage problems. I'm averaging 12.5 MPG and the cars runs excellent. I don't care what it needs it shouldn't get that kind of mileage. I drive it easier than my 80 year old grandma drives her new yorker Quote Link to comment Share on other sites More sharing options...
Guest Gp crazy Posted December 26, 2003 Report Share Posted December 26, 2003 if you run the motor in high gear does it have a high speed miss? ie. any speed above 50 mph. if so look at the coil packs just take a inductive timing light to each wire you may or may not find the bad wire or coil pack. rember two cyl. to a coil it's 1,3 then 2,4 then 5,6 or somthing like that. also look at the heated air intake grid it looks like a honey comb if it's dirty do not clean it off with any liquid you will fry it!!!!!!!! also look at o2 sensor for the 20 dollars it's an easy install if you haven't done it in the last 4-6 years they get slow acting and will decrese your fuel milage by 20 % also if you have a friend that has a scan tool. it can tell you all most any thing you want with in reason. air fuel mixture, any codes you may have and cross count's on o2 sensor. low cross counts are not a good thing this means o2 sensor is slow or inactive. also check the vac it should read about 16.0 in. or a little higher with motor warmed up at idle. you might want to look at the converter at night after about 1.5 hr drive look under the car you may find the converter glowing cherry red if so it wont last long. which means you are getting to much fuel. if you want to get really on it you could check the back pressure in the exhaust it should not be over 1.5 pounds. also check the fuel pressure running and leak down there are magic numbers for this but i don't know what they are. just a few thoughts from jeff Quote Link to comment Share on other sites More sharing options...
excelsior Posted January 1, 2004 Report Share Posted January 1, 2004 hopefully some stp & o2 sensor will do the trick....spark plugs can also cause problems....exhaust perhaps? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.