pontiacfreak142 Posted December 11, 2009 Report Share Posted December 11, 2009 i have a 1993 grand prix with the 3.1 V6 that im pretty sure is getting horrible gas mileage. I just looked up the specs and these cars we rated at 19/30, but i would honestly be suprised if im getting much better than 10. Im going to put new plugs in it and possibly wires, but what else should i try? The car does have 240k miles on it, could that be some of the problem? Quote Link to comment Share on other sites More sharing options...
Bam Posted December 11, 2009 Report Share Posted December 11, 2009 Why don't you drive it like 3 tanks through and calculate your actual mpg, then decide if it really is bad or not? I'd do that first before throwing money away. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted December 11, 2009 Report Share Posted December 11, 2009 calculate your actual mpg first...and see where you are Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 11, 2009 Author Report Share Posted December 11, 2009 some how i dont think thats necessary when ive gone 51 miles and sucked down almost a 1/3 tank of gas on a 15 gallon tank lol. Quote Link to comment Share on other sites More sharing options...
SRTurbo04 Posted December 11, 2009 Report Share Posted December 11, 2009 gas gauges read liek shit my srt goes from full to a half in liek 75 miles then the "bottom" half goes another 175-200... same as my mustang but my expedition is direct opposite stays in the higher part then drops like a brick dont reley on the gas gauge calculate your true mpg an go from there you lazy turd Quote Link to comment Share on other sites More sharing options...
Bam Posted December 11, 2009 Report Share Posted December 11, 2009 oMG i agree with paul. DO NOT watch your gas gauge, they are never accurate. CALCULATE your miles. If you don't want to do the whole tank. Fill it up until the pump stops automatically. Dry 50+ miles, then top it off the same way again. This won't be as accurate as an entire tank of gas, but will be much more accurate than watching a 20 year old gauge. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 11, 2009 Author Report Share Posted December 11, 2009 oMG i agree with paul. DO NOT watch your gas gauge, they are never accurate. CALCULATE your miles. If you don't want to do the whole tank. Fill it up until the pump stops automatically. Dry 50+ miles, then top it off the same way again. This won't be as accurate as an entire tank of gas, but will be much more accurate than watching a 20 year old gauge. true i guess lol. Come to think of it, i never really have run this thing out of gas, so i dont know how fast it drops when it gets towards the bottom of the gauge lol. Although i think i am going to put new plugs in it anyway, i pulled the front 3 out and they all looked ancient and nasty. Quote Link to comment Share on other sites More sharing options...
Guest Removed Posted December 11, 2009 Report Share Posted December 11, 2009 check and make sure the FPR is not leaking thru the vacuum line into the top of the intake Quote Link to comment Share on other sites More sharing options...
TTQ B4U Posted December 12, 2009 Report Share Posted December 12, 2009 I think this extra cold snap stole 2-3mpg from me even on the 4-banger. I remember my GXP would average 12mpg in this weather. Quote Link to comment Share on other sites More sharing options...
Guest tbutera2112 Posted December 12, 2009 Report Share Posted December 12, 2009 fuel filter? Quote Link to comment Share on other sites More sharing options...
99ta Posted December 12, 2009 Report Share Posted December 12, 2009 I have the same motor in my monte and I am getting 30mpg and it has 205k miles.... Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 12, 2009 Author Report Share Posted December 12, 2009 fuel filter? thats going to be one of the next things i check. Quote Link to comment Share on other sites More sharing options...
Cordell Posted December 12, 2009 Report Share Posted December 12, 2009 Some tune up stuff sure won't hurt if its pretty old, but I'd check the actual MPGs. Quote Link to comment Share on other sites More sharing options...
nurkvinny Posted December 12, 2009 Report Share Posted December 12, 2009 Clogged cat. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted December 12, 2009 Report Share Posted December 12, 2009 if you have a scanner check the coolant temp sensor reading when the car is at operating tempature the computer will accept -40 to +400 as acceptable and if it goes bad and stays low the computer leaves it in cold start enrichment all the time so the fuel economy suffers and you get no check engine light becuase the sensor range is so wide open Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 13, 2009 Author Report Share Posted December 13, 2009 Some tune up stuff sure won't hurt if its pretty old, but I'd check the actual MPGs. yea, thats what i kinda figured to. ive swapped 3 plugs so far and they do look pretty bad. although im thinking paul was right, i havent hit a half tank yet, and im over 100 miles now. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 13, 2009 Author Report Share Posted December 13, 2009 Clogged cat. luckily, when i get a nice day, its coming off anyway. Plus im going ricer and putting a CAI i had bought for the firebird, on it cause it was to small for the bird, but perfect size for this thing lol. Quote Link to comment Share on other sites More sharing options...
pontiacfreak142 Posted December 13, 2009 Author Report Share Posted December 13, 2009 if you have a scanner check the coolant temp sensor reading when the car is at operating tempature the computer will accept -40 to +400 as acceptable and if it goes bad and stays low the computer leaves it in cold start enrichment all the time so the fuel economy suffers and you get no check engine light becuase the sensor range is so wide open ill have to do that, i know my dad has one at his shop. Quote Link to comment Share on other sites More sharing options...
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