Getting 210 miles on tank of gas....
Tried Fuel injector cleaner and octane boost to maybe clean something but not much benefit at all.
Try Seafoaming your car. Also, go to Autozone and get a $7 can of MAF cleaner. Your MAF may be dirty, which could cause problems. You may want to consider changing the other O2 sensor, also. Usually, if one goes bad, the other going bad is right around the corner. You may not be throwing a code, but it may be on its way out, causing you bad mileage.
Also, a real dynotune would seriously help your situation, especially if you're running longtubes untuned. Since you never floor it, you're probably running pig rich, causing poor mileage.
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While 210 miles per tank isn't great, it's unlikely you've got anything "seriously wrong" with your car. You've removed EGR and have bigger (heavier) 18" rolling stock, both of which can reduce mileage some. I've had my Z since it was basically new (6k miles), and bone stock with 3.23's I never got better than 20 mpg. Usually averaged ~17-19. Seafoaming & maf cleaning is a good suggestion. I'd also make sure you have fresh o2's, they don't last near as long when you've got longtubes. Lastly, with your intake/exhaust mods have most definitely thrown your tune a off. A correct tune for your mods will net you the biggest improvement IMO.
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Then I got my cam in and the supporting mods in my SIG.
I still only get 210 220 miles per tank! Go figure.
My AFR is flat and steady at 13.
Are you running synthetic fluids?
Im guessing the tune is hurting you A/F ratio some.
What is you cars RPM when your cruising?
Now I cant give you a very good answer since mine is a 2 spd car so i hope some auto guys can chime in here. I know my car with the 4.10s at 70 is under 2k RPM in 6th gear.
Around down im getting roughly what you are 210-220 per tank usually 13-14 gallons when filling up. But if i get on the freeway or highways at all it can shoot up to 20 mpg plus no problem.
While 210 miles per tank isn't great, it's unlikely you've got anything "seriously wrong" with your car. You've removed EGR and have bigger (heavier) 18" rolling stock, both of which can reduce mileage some. I've had my Z since it was basically new (6k miles), and bone stock with 3.23's I never got better than 20 mpg. Usually averaged ~17-19. Seafoaming & maf cleaning is a good suggestion. I'd also make sure you have fresh o2's, they don't last near as long when you've got longtubes. Lastly, with your intake/exhaust mods have most definitely thrown your tune a off. A correct tune for your mods will net you the biggest improvement IMO.
It's not a big problem to those who don't care about fuel economy. However, for most of us where fuel economy is important, it is a huge problem. If these cars got 50% less fuel economy, most people on this site would not own them. I know I wouldn't own a 13 mpg car. My car gets 22 mpg in the summer, 19 mpg in the winter with 50/50 driving all the time.









