Gas Mileage down the Whole!
05-10-2006, 10:27 PM
#1
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Gas Mileage down the Whole!
OK i have an 89 gt convertible with an auto in it. i get 155 miles her tank and that's driving moderate.... and IM STOCK with 187xxx miles besides a full exhaust system ! WTF? ive been trying to figure this problem out for forever! ive changed everything! full tune up.. fuel filter and even changed the fuel pump, wires plugs, new dizzy cause iw as cracked.. new 02's.. everything!! AHHH someone please help me! if i dont figure out this problem, i will garage the car for the summer and drive my moms lexus.
05-10-2006, 11:34 PM
#6
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Join Date: Sep 2004
Posts: 394
RE: Gas Mileage down the Whole!
First off, you really need to compare miles per gallon instead of miles per tank. Because, you may fill your tank at a different level than I fill mine so the comparison is invalid. That said, I usually get between 20 to 24 mpg in my '90 GT Convertible AOD that's bone stock. That works out to a little over 200 miles per tank based on where I fill the tank.
All that said, you might want to clean your engine upper with a SeaFoam treatment and add some to your tank to clean the injectors. Also, take some aerosol throttle body cleaner and clean your throttle body and IAC. Check your air filter (replace if it's dirty), make sure your tires are inflated properly. And make sure your timing is set right (might try taking it up slightly if you're not having any spark knock issues, then if you get spark knock drop it back down). Oh, and when you changed your plugs, did you make sure they were gapped properly (some folks overlook that)?
All that said, you might want to clean your engine upper with a SeaFoam treatment and add some to your tank to clean the injectors. Also, take some aerosol throttle body cleaner and clean your throttle body and IAC. Check your air filter (replace if it's dirty), make sure your tires are inflated properly. And make sure your timing is set right (might try taking it up slightly if you're not having any spark knock issues, then if you get spark knock drop it back down). Oh, and when you changed your plugs, did you make sure they were gapped properly (some folks overlook that)?
05-11-2006, 12:01 AM
#7
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RE: Gas Mileage down the Whole!
yes they were gapped properly. and i used to get around 225 miles per tank until i installed my 95 rear end in my 89 for the 5 lug convserion.. it has stock 2:73 gears in it..and one bearing is bad in the rear.. would htat bad bearing cause my gas milage to go downhill that bad?
05-11-2006, 12:26 AM
#9
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RE: Gas Mileage down the Whole!
ORIGINAL: black89gt
yes they were gapped properly. and i used to get around 225 miles per tank until i installed my 95 rear end in my 89 for the 5 lug convserion.. it has stock 2:73 gears in it..and one bearing is bad in the rear.. would htat bad bearing cause my gas milage to go downhill that bad?
yes they were gapped properly. and i used to get around 225 miles per tank until i installed my 95 rear end in my 89 for the 5 lug convserion.. it has stock 2:73 gears in it..and one bearing is bad in the rear.. would htat bad bearing cause my gas milage to go downhill that bad?
05-11-2006, 12:48 AM
#10
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RE: Gas Mileage down the Whole!
well the door tag is on the sn95 "M" is the same letter as on my foxbody which is also "M" but sitll even with 3:08's i wouldnt have reduced gas milage that much. maybe its hte bearing..