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tuning for MPG

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95weclipse

10+ Year Contributor
308
3
Jun 26, 2009
LaSalle, Illinois
I need help with getting my car tuned, my mods are on my profile, I just need to get this tuned, my car only gets 20-21, ran a compression test the other day came back all above 170, think my pcv is stuck open, will be getting a new one soon, I don't need a 10 sec tune, just to get the "base tune" done i guess any help would be greatly appreciated, I am using ecmlink v3 lite btw
 
Turbo doesn't hurt mpg and in ways in can help.

yeah until it starts raising your fuel pressure.

might get flamed but Audi did it right with there turbocharged 1.8t and yes I do own one and it does get great gas mileage, granted the turbo is small but there is always decent power in the 1000 to 3000rpm range. Even with it being auto I still see over 30mpg on average. Also I wish my eclipse had the head off the Audi, they are beautiful,
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What tires and rims are you running on at 60PSI?

This was on my 4e-fte tercel. I was using bmw 14" with ast's. Went from 38mpg to 42mpg with the pressure.

I run 50ish on my mighty max with stock steel wheels and junk tires.


Some other tricks i have done is run the motor hotter and used a small amount of acetone.
 
Damn if I wanted more MPG; I would not have brought a 4g63. I would be driving a 420a or a 1.8. The price you pay to zoom-zoom....
 
I can get 30+ on the highway if i stay bten70-75. City iget 300+ out of every tank. It depends on your driving and maintenance .
I just took a 420 mile trip to FL. Avearage spd btwn 80-85. Went to church the beach them filled up so about 430-440 total out of that tank.
 
The gas tanks on a 2G GST is larger than the GSX by about 2 gallons. You must calculate mpg & not use miles per tank when checking mileage. My '95 GST get a little better mileage by about 24 mpg than my '97 GSX with 21 mpg and this is only stop & go no hiway miles.
 
My gf's spyder averages 26mpg in town with her driving, and she loves to hear her turbo whistle and the BOV. My built talon can pull around 25. Leaning out the cruise in the spyder I know she can easily pull 30 in town. On our move to AZ we put over 3000 miles on both, I was averaging 32mpg and she was averaging almost 40 cruising up and down through the rockies.

I do have a question about MPG that I haven't been able to test, is less RPM or more Vacuum beneficial to MPG increase? Obviously both would be ideal, however, cruising, especially through town it's hard to maintain high vacuum, and low rpm's. I used to shift into the highest gear I could cruise in without bogging, however, when I'd go to pass someone or try and climb a hill down the interstate you're putting very high load on the engine, building good amounts of boost to maintain speed. If I keep it in a lower gear you increase the RPM, but keep the vacuum high, essentially keeping engine load down.

So, any input? High RPM and low load, or low RPM high load = better MPG?
 
Interested in a response. My car cruises between. 14.2- 15.5.. Is that too lean?
 
Interested in a response. My car cruises between. 14.2- 15.5.. Is that too lean?

I leaned my old 3g out to ~16 AFR's and was pulling 41 mpg highway out of it with no knock and no overheating issues. Timing was still factory or above in the upper RPM's.
 
I think some of the guys here are missing the point. We do not want MPG compared to other makes or models. We want better MPG compared to our performance tune. I have a map for highway and one for drag strip. I can't drive my car on a high way with the performance map, right.

It's not a bad thing to want to save some $$$ that can be useful...
 
I regularly hit 30+mpg in my stock 96 GSX. There are big MPG gains to be had from dropping your speed from 75mph to 65mph. I can only pull ~24 if I run 75mph. It would benefit greatly from a 6-speed or at least an Evo3 5th gear. I am curious what I could hit with a lean tune though.

These cars really do not do well for mileage. I have hit 27mpg with my 5-speed 3000GT running 75mph. I was running a standalone ECU though.
 
id say if you were looking for good fuel mileage, go buy a cheap fwd beater i.e Honda, cavalier, neon, focus, hell even a crown vic. i DD one and i see anywhere from 23-25 city and up-to 32 mpg with 93. i've heard people say oh higher octane doesn't give you better fuel mileage...ok well lets say i fill up with regular, I have a higher chance of detonation (knocking,pinging etc.) than if i were to run 93. so if i run regular and my ecm sees "hears" knock it'll retard the timing so the engine does not get harmed... retarded in timing equals power loss witch will result in lower mpgs because the engine now has to work harder to get up to or maintain the speed you want to go. on another note does anyone elses find it funny Honda uses our stock 450's as an upgrade?
 
your engine is still going to be working harder to make the power that it needs to maintain or keep the speed your going. factories try to tune afrs to 14.7:1 as closely as they can. this stoich afr gives you good economy as well as decent power. not too lean not too rich sort of speak. i would not personally try to retard timing and lean the afrs to get better fuel mileage. possibilities of burnt rings, melted if too extreme. not worth it in something that ive got money into. imo you need a good pwer to weight to acheive good fuel mileage. im not saying our cars dont have good power to weight its just to make the power our cars need to be in boost. force more air into the engine you also have to add fuel...in return (especially if your tuned for performance) equals lower mpgs.
 
on another note does anyone elses find it funny Honda uses our stock 450's as an upgrade?
They have smaller capacity motors where it makes sense along with lighter vehicles that zips around the corner quicker.

Have to realize, we drive pretty heavy "pigs" compared to actual Japanese made vehicles since our vehicles are made here in the States...and Americans loves heavy cars.

You need the 14.7:1 ratio in both economy and performance for best efficency in both cases.

Thus, instead of hitting the motor, try different driving styles - shiftpoints, clutch, tire pressures, maybe some weight reduction, et.al.
 
He has ECMLink V3 Lite... Which is much better than a SAFC (IMO).... Just saying. It is the last sentence of the OP's Post.

However, you both have valid points. E-85 is not supposed to be used in the stock fuel system of the DSM. But if you replaced certian fuel components, you will be able to run E-85 successfully without any issues other than a tune of course.


What is this statement based on? I have a friend that has been running e85 on stock lines and filter for 3 years. Only dif is he has two 190 pumps, everything else, stock.

More online BS dsm myths busted.
 
My afc tuning days I didn't really tune for afr's but I would tune the fuel trims low, mid, high until they where all around the 110% range. You can probably tune higher as long as there's no lean miss fire.
 
id say if you were looking for good fuel mileage, go buy a cheap fwd beater i.e Honda, cavalier, neon, focus, hell even a crown vic. i DD one and i see anywhere from 23-25 city and up-to 32 mpg with 93. i've heard people say oh higher octane doesn't give you better fuel mileage...ok well lets say i fill up with regular, I have a higher chance of detonation (knocking,pinging etc.) than if i were to run 93. so if i run regular and my ecm sees "hears" knock it'll retard the timing so the engine does not get harmed... retarded in timing equals power loss witch will result in lower mpgs because the engine now has to work harder to get up to or maintain the speed you want to go. on another note does anyone elses find it funny Honda uses our stock 450's as an upgrade?

So basically what you're saying is, if go throw in 110 leaded race fuel in my bone stock gvr4 I will get awesome mpg because it'll never knock? If so that is completely wrong, higher octane fuel burns slower, which is why we need more e85 to maintain the same power as say 91. Factory cars tuned on regular (87-89 depending on your location) should run regular because the timing and fuel maps are based around the burn rate of the fuel. My roomate was under the assumption that his dodge dakota should get better mpg out of 91 than 89, even though factory calls for 89. He could never pull more than 12mpg out of it in town, finally I explained to him why. He was consistently pulling 14-15 mpg out of it after switching back to 89.

Also the driving style is the biggest key, I didn't buy my gvr4 to build into a drag monster, I bought it for a DD. I want it to get as good of mpg as possible, so not everyone buys dsms to make monsters of.
 
Thus, instead of hitting the motor, try different driving styles - shiftpoints, clutch, tire pressures, maybe some weight reduction, et.al.

This ^.

Changing your driving style and increasing power to weight ratio are by far the best ways to increase gas mileage. Tweaking the timing, AFR, or other tuning parameters pales in comparison. Try dropping your highway speed by 5 mph and watch what happens to your mpg.

higher octane fuel burns slower, which is why we need more e85 to maintain the same power as say 91.

Actually, more E85 is required because it contains less potential energy in it's chemical bonds than gasoline does....not because it burns slower. ;)
 
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