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I have a 1991 Cutlass Ciera with the 3.1 six engine. I think I canimprove my mpg by adjusting the shift point of the 3-4 shift. Currently the tranny won't shift into fourth gear unless I am going 50 mph. I don't see why it shouldn't shift into top gear at 35 or 40 if I am on level ground and driving a steady speed. Can it be adjusted to shift at a lower speed?


Any ideas? Also,any ideas on improving mpg on this engine? I was getting 26-27 mpg and improved that to 31.5 by dropping my hightway speed to 57 and running cruise control all the time.

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TIRE PRESSURE, TIRE PRESSURE , TIRE PRESSURE. MOST IMPORTANT FACTORE. IF YOU STILL HAVE THE ORIGINAL SIZE ON THE CAR THEN USE THE TIRE PRESSURE LISTED ON THE PLACARD ON THE DRIVERS DOOR. THE MANUFACTURER OF THE CAR KNOWS BEST.
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Thanks for the answer. I forgot to mention that. I have checked the pressure like a demon(in fact I have a gauge in my pocket right now). I am running the original size tires and I think I goosed the pressure up 1 or 2 lbs, I have them running at 35 psi when they are warm. Thanks for replying![img]smileys/smiley17.gif[/img]
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i write this with all respect possible but why are you increasing the air pressure? the manufacturer of the auto has spent endless hours designing a car that with give maximum tire mileage and fuel economy on the prescribed air pressure. please dont be offended but the manufacturer of the auto knows more about this car than you and i will ever know. respectfully. my example would be my own gmc jimmy that has the lease expensive white letter tire i could find, by keeping the tires rotated and tire pressure per the mfg of the auto i recieved 49,450 miles from the tires.
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My friend, I'm not the least offended and thank you for taking the timeto reply. My thinking is that gasoline is more expensive than tires. I read that the guys that are real nut cases about improving their mpg'sget their air pressure in the tires way up. Now I'm probably only half nuts so I only bumped the air up alittle bit. My mileage has gone up, mostly from dropping my speed, but I feel some of it is attributible to higher air pressure. And if I can find an answer on dropping the shift point on my trannydown to say 40, I think I can get another significant improvement in mpg. However, I'm not going to do it if it means damaging the car.



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if you get some high performance plugs and a cold air intake the added power will change shift points and improve mileage.As far as the air press. goes I run my tires at 42 on my 91.The manufacturer sets tire press. to give both mileage and maintain the best contact with the road so the more press. the less control under spirited driving but if you drive sanely you got no worries.With the power adders and the tire press. I''m getting 34mpg with an od shift at 42 mph in a cutlass with a 3.1 and over 3000,000. No offense to any one that is just my personal opinion due to my own experience in a cutlass.

To bean77 and ilikecars:


Thanks for the replies. I check this forum every once ina while and saw bean''s reply tonight. Where did you get the cold air intake and do you think the purchase will pay for itself in gas savings?


I cannotice adifference in handling with the air pressure at 40 lbs psi, but as you point out, I''m not at IndyI''m just driving in a straight line at 57 mph. No drama, no theatrics. On a lightly travelled stretch of Interstate I think I can trade the loss of handling for additional mpg.

I bought mine off ebay for $25 and it has more than paid for itself

Hey bean:


Thanks for the reply. I''ll have my nose in eBay this weekend tosee if I can''t locate one of those cold air intakes. -Mac