seabass Posted February 23, 2005 Report Share Posted February 23, 2005 HOW CAN I IMPROVE MY GAS MILEAGE, MY DASH IS SHOWING 9 MPG, WHICH SEEMS PRETTY ACCURATE , IT SEEMS TO BE LIKE SOMEONE IS SUCKING IT OUT WITH A STRAW, ANY CHEAP FIX ? I DO HAVE NEW 02 CENSORS , BUT THAT ONE BEHIND THE MOTOR NEAR THE FIRE WALL IS A *smurf* TO CHANGE THE MECHANIC BROKE THE FIRST AND HAD TO GET A NEW ONE FOR ME , SINCE I PURCHASED IT MYSELF, HE BROKE THE WIRES ON THE CENSOR. SEABASS 93 STS NORTHSTAR (76200) Link to comment Share on other sites More sharing options...
tmpafford Posted February 23, 2005 Report Share Posted February 23, 2005 Try a few cheap things first. Replace the PCV valve. Costs about $3. Dont trust the part number listed on most auto parts store's computer. Drive to the store and pop the original out and get them to find the exact match. If I remember correctly, it is located on the drivers side, close to the firewall near cylinder 7. This is a little ball valve that allows the engine to suck the fumes that excape into the cylinder heads back through the engine. Replace the air filter. you should be able to find a good oiled cotton filter like K&M for you car. Allows air to flow better than a paper filter. Should be about 35$ Replace the spark plugs. About 20 bucks. Go with AC Delco Replace the wires. About 150 bucks. Go with AC Delco Check the Exhaust Gas Recirculating (EGR) valve. I have not done this yet so I can't say how much they cost. Check into doing a WOT. Not sure if it is recommended for the 93. Check this board for examples on how to do it. It will burn all the crud out of the cylinders and get the piston rings to seal better. And its FREE! 9 mpg is very poor. I was getting about 14 mpg at my worst in my 97 STS. Link to comment Share on other sites More sharing options...
PAUL T Posted February 23, 2005 Report Share Posted February 23, 2005 Do not forget the fuel filter. You might do a throttle body cleaning and an EGR tube cleaning. Check your tire pressure. You could also clean the phenolic plates under the intake manifold if it has them. How far do you drive it? Short trips will kill gas mileage. Run it on premium and squeeze some more MPG. Also, check for diagnostic codes. Link to comment Share on other sites More sharing options...
seabass Posted February 23, 2005 Author Report Share Posted February 23, 2005 ITS MOSTLY LOCAL DRIVING , I WILL TRY AND MAKE SOME CHANGES AND CHANGE SOME PARTS. 93 STS SEABASS Link to comment Share on other sites More sharing options...
Scotty Posted February 23, 2005 Report Share Posted February 23, 2005 This sounds way too low although local driving CAN decrease it greatly. You have to have something wrong in my humble opinion, what codes are you getting? Are your O2 sensors are messed up I can't understand what you are trying to say below. What size rims and tires and what pressure are you running? When was it tuned up? How heavy is your foot? Link to comment Share on other sites More sharing options...
BSchlossmann Posted February 23, 2005 Report Share Posted February 23, 2005 My 93 4.6 Eldorado gets 20 MPG around town and 25+ on the highway. The Winter grade of gas causes the mileage to drop about 10 percent. Check to make sure that your brakes are not dragging. The phenolic spacers typically require cleaning every 100K miles or so. The symptom will be that the engine will shudder under light acceleration. This de-carboning takes a couple of hours to perform and is well documented in the archives. There has to be something very wrong to be getting only 9 MPG. Maybe others on this board have experienced the same type of problem and can recommend a solution. Link to comment Share on other sites More sharing options...
Wild.Bl Posted February 23, 2005 Report Share Posted February 23, 2005 My son, "MIke D", and I have three 93 STS N* vehicles. My son is an aggressive driver. When he drives any of the vehicles the worst mileage is 16 city/ 21 hwy. When I drive in a non aggressive mode I get 19-22 city/ 24-25 hwy. With only 76K on your engine, you should be doing at least that good. These vehicles have 86K, 176K, and 206K on them. I keep them tuned and air intake system clean. I use premium fuel from any source. I only use AC Delco replacement parts. It sounds like a complete tune up and cleaning should be your first approach. Also check for codes in the computer and run a performance diagnostic. Another possibility is leaking fuel rail. There was a recall on some 93s. Good luck with your search for better mileage as it should also result in better performance! Link to comment Share on other sites More sharing options...
AaronM Posted February 23, 2005 Report Share Posted February 23, 2005 I had very bad gas mileage as well. My car ran rich and it smelled like rotten eggs sometimes. My air and cooland temperature sensors were off. Once they were replaced, I got 20mpg! 18 Year Old Male Black 1992 STS 4.9L 90,XXX Miles Flowmaster 80 series muffler Link to comment Share on other sites More sharing options...
growe3 Posted February 24, 2005 Report Share Posted February 24, 2005 Replacing the air filter may be helpful, but K&N is pretty much a waste of money. See link below for some recent discussion on this, much more in the archives. 9 MPG is way to low, I have two 93' STS's and both will average 20+ MPG. If a lot of in town driving is done they will drop to about 17-18 MPG. -George http://caddyinfo.ipbhost.com/index.php?showtopic=5147 Drive'em like you own 'em. - ....................04 DTS............................ Link to comment Share on other sites More sharing options...
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