My Corolla has one and i get fairly bad economy. I used to run it on 91 octane but then switched to 95 because the manual stated it, which gave it a little better economy. But the cars been run on 91 for the last 19 years - would that make the engine bad?
Also - does the 4AF have a rev limiter?
Last edited by darth-grantius; 09-03-2009 at 02:29 AM.
I don't think they have that much difference in mpg as long as the 4AF is well tuned. As for gas, I used to run premium but I do regular now. Just adjust the timing and all...
And I don't think the 4AF has a rev limiter... I have 240000+ miles, I wouldn't wanna try.
I don't think they have that much difference in mpg as long as the 4AF is well tuned. As for gas, I used to run premium but I do regular now. Just adjust the timing and all...
And I don't think the 4AF has a rev limiter... I have 240000+ miles, I wouldn't wanna try.
Carbs go out of tune over time. Then you have to do the fine adjustments... ie idle, fuel trim, etc. EFI is all electronic so no re-tuning is required (not as much as carbs). If everything is tuned close to perfect, mpg should be very good. Right now, I get between 24mpg up to 37mpg! I think I reached 37mpg by letting my car coast down at idle when I going down slopes on highways and stuff (i have a stick).
If the car lacks power, runs rich, runs lean, spits, choke, runs rough, idles rough... Carbs likely out of tune.
Carbs go out of tune over time. Then you have to do the fine adjustments... ie idle, fuel trim, etc. EFI is all electronic so no re-tuning is required (not as much as carbs). If everything is tuned close to perfect, mpg should be very good. Right now, I get between 24mpg up to 37mpg! I think I reached 37mpg by letting my car coast down at idle when I going down slopes on highways and stuff (i have a stick).
If the car lacks power, runs rich, runs lean, spits, choke, runs rough, idles rough... Carbs likely out of tune.
I rebuilt my carb last year and it gets far bettr gas mileage now. The only pia was adjusting the float because if you don't get it right you gotta take the whole thing apart again.
when I still had my stock sized wheels and tires I could get 40 mpg out of my 4AF driving really carefully. but as soon as I put the 15s with 205/50/15s on it that went out the window. I was getting about 24 mpg average when my engine died at 225k miles
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'01 Impreza 2.5 RS - Mud flaps, skid plates, Gravel Dampers
'89 RX-7 TurboII - Megasquirt-3 - 270 rwhp
'89 Corolla SR5 - 4AGE ST 20V 6spd LSD, Megasquirt II, Koni Race Dampers + GroundControls + camber plates F/R, GT-S Rear brakes
'81 BMW R65 For Sale: GT-S strut bar + Front GT-S koni yellows
it's easy to put a new carb on. Unbolt everything attached to it and then reverse for the new one.
If the car is tuned properly the gas milage should be about the same, as long as you don't push it since carbs just start to dumb fuel in.
Only time I have run premium in mine was when the carb needed to be cleaned the extra octane made it run better.
No rev limiter on my 4af, hit 8000 with it before... DO NOT RECOMMEND since the valve float at 7000 (or did when new), I did it accidentally when I first started driving it and was messing around.
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