Horribly low Gas Mileage
09-04-12, 10:36 PM
#1
wheelman for hire
Thread Starter
Horribly low Gas Mileage
I've had my 7 for almost a year now, and since day 1 I've gotten poor gas mileage, about 11-14 on average. Every trip I pay attention to the mileage. changed the plugs and fuel filter a month or so ago, everythings stock on it. its always leaking oil from a few spots but I recently noticed it dripping from a new point below the car further back away from the engine, it was oil but did not look like the dark oil thats in it ( I also pay attention to my oil and where it leaks) this oil was light in color almost like new oil, could this be fuel/oil mix? I can smell fresh gasoline sometimes but not very often. Any thoughts or suggestions as to why I have such low MPG? for a 81 12a I dont think thats a normal MPG is it???
I also usually shift in lower rpms to try not to let the secondaries open lol anyone know what rpm range the secondaries usually open at? Id like to jb weild em shut just to get better mpg at this point lol...
I also usually shift in lower rpms to try not to let the secondaries open lol anyone know what rpm range the secondaries usually open at? Id like to jb weild em shut just to get better mpg at this point lol...
09-05-12, 12:14 AM
#2
The secondaries don't open based on RPM; they open based on engine load as determined by vacuum. And, if they don't open when they need to in order to maintain proper flow based on demand, your efficiency suffers which ironically will lower your mileage.
09-05-12, 07:09 AM
#4
Waffles - hmmm good
iTrader: (1)
Your gettin about 10 mpg below average. You need to go over your whole fuel system and make
sure theres no leaks and all the hoses are good. Then I would start looking at the carb and
ignition. Note I put ignition last, its likely leaks or a carb issue. Also if you still have the rats
nest then that a whole another ball of wax right there that will need attention. I'd replace all
rubber for the fuel and vacuum lines as a start.
sure theres no leaks and all the hoses are good. Then I would start looking at the carb and
ignition. Note I put ignition last, its likely leaks or a carb issue. Also if you still have the rats
nest then that a whole another ball of wax right there that will need attention. I'd replace all
rubber for the fuel and vacuum lines as a start.
09-05-12, 11:09 AM
#6
Full Member
Mileage:
Is it ported? Is your idle good? Do you have a stock Nikki or?
'Since you got it'. Sounds like you're like me, too, that you keep track of everything (I have a spreadsheet that I update whenever I dink with it). If it's happening since you got it, it's possible that it's running lean. How's your idle? When I started dinking with the Nikki I dropped from 18 to 13 mpg (but on the way back up again). But before you dink with the carb (assuming you have a Nikki)...
If your rats nest is still intact: Get the car warmed up. Get your can of trusty carb cleaner out. Spray your rats nest in bursts on each hose. If the idle changes, you have a leak. Replace hoses as necessary.
Spray around your Air Control Valve on the other side of the engine - and stick that red tube in under the carb heat shield when you do it (start from the bottom up, though).
Whether that worked or not, still check the floats on your carb (front and back). They should be at the halfway mark. You'll need a mirror to check the back float.
That's the low dollar cheap and easy stuff. From there I'd inspect the ignition coils and wires.
Second, Oil leaks. Check your oil metering pump tubes (front of engine, they drop down to the OMP) - if they are leaking, you'll get blowback that will drip down. There's another oil leak that's more pesky but that's a more detailed fix (https://www.rx7club.com/1st-gen-arch...ak-fix-864358/ ) for that. Also check the gasket down below... in cleaning out my engine I saw I gotta do mine... (yay...)
The gas smell you're getting now and then might be coming through the charcoal canister. If that's it, that is normal. Rev the engine and look for leaks. Hint: Don't smoke while doing this. I did see someone lose an eyebrow doing that.
Is it ported? Is your idle good? Do you have a stock Nikki or?
'Since you got it'. Sounds like you're like me, too, that you keep track of everything (I have a spreadsheet that I update whenever I dink with it). If it's happening since you got it, it's possible that it's running lean. How's your idle? When I started dinking with the Nikki I dropped from 18 to 13 mpg (but on the way back up again). But before you dink with the carb (assuming you have a Nikki)...
If your rats nest is still intact: Get the car warmed up. Get your can of trusty carb cleaner out. Spray your rats nest in bursts on each hose. If the idle changes, you have a leak. Replace hoses as necessary.
Spray around your Air Control Valve on the other side of the engine - and stick that red tube in under the carb heat shield when you do it (start from the bottom up, though).
Whether that worked or not, still check the floats on your carb (front and back). They should be at the halfway mark. You'll need a mirror to check the back float.
That's the low dollar cheap and easy stuff. From there I'd inspect the ignition coils and wires.
Second, Oil leaks. Check your oil metering pump tubes (front of engine, they drop down to the OMP) - if they are leaking, you'll get blowback that will drip down. There's another oil leak that's more pesky but that's a more detailed fix (https://www.rx7club.com/1st-gen-arch...ak-fix-864358/ ) for that. Also check the gasket down below... in cleaning out my engine I saw I gotta do mine... (yay...)
The gas smell you're getting now and then might be coming through the charcoal canister. If that's it, that is normal. Rev the engine and look for leaks. Hint: Don't smoke while doing this. I did see someone lose an eyebrow doing that.
I've had my 7 for almost a year now, and since day 1 I've gotten poor gas mileage, about 11-14 on average. Every trip I pay attention to the mileage. changed the plugs and fuel filter a month or so ago, everythings stock on it. its always leaking oil from a few spots but I recently noticed it dripping from a new point below the car further back away from the engine, it was oil but did not look like the dark oil thats in it ( I also pay attention to my oil and where it leaks) this oil was light in color almost like new oil, could this be fuel/oil mix? I can smell fresh gasoline sometimes but not very often. Any thoughts or suggestions as to why I have such low MPG? for a 81 12a I dont think thats a normal MPG is it???
I also usually shift in lower rpms to try not to let the secondaries open lol anyone know what rpm range the secondaries usually open at? Id like to jb weild em shut just to get better mpg at this point lol...
I also usually shift in lower rpms to try not to let the secondaries open lol anyone know what rpm range the secondaries usually open at? Id like to jb weild em shut just to get better mpg at this point lol...
09-05-12, 11:10 AM
#7
Full Member
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