A few fuel MPG Questions!
02-06-2011, 10:56 AM
#1
Intrawebz Wizard
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A few fuel MPG Questions!
Ok sense I've gotten my motor rebuilt my MPG has been really poor lately, around 15MPG at best And I'm wondering why...
No fuel in the oil, the oil is clean, spark plugs are a healthy color, Fuel filter is new, No injectors leaking, no fuel leaks anywhere that I can see, the engine is running smoothly, and the valves and TPS are adjust to the specs noted in the FSM
Any idea why my MPG sucks? Oh and I wanted to ask if having a broken charcoal canister would cause this? The Smaller ported vacuum line snapped off and I can get it glued back on so I just capped the line, leaving the other 2 lines attached.
No fuel in the oil, the oil is clean, spark plugs are a healthy color, Fuel filter is new, No injectors leaking, no fuel leaks anywhere that I can see, the engine is running smoothly, and the valves and TPS are adjust to the specs noted in the FSM
Any idea why my MPG sucks? Oh and I wanted to ask if having a broken charcoal canister would cause this? The Smaller ported vacuum line snapped off and I can get it glued back on so I just capped the line, leaving the other 2 lines attached.
02-06-2011, 12:32 PM
#5
Intrawebz Wizard
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Timing at 10*
Spark plug gap at 1mm
Tire pressure at 32PSI on all 4 corners
And no Vacuum leaks!
Been using 91 from Mavrick and I've been driving it the same way sense I got the Z but only sense after the rebuild as the MPG gone down.
02-06-2011, 09:46 PM
#9
Intrawebz Wizard
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... Hmm... That reminded me of the AFM... Tomorrow I'll do an OMH and Volt Test from the ECU plug and see if theres something wrong there
Oh heres something else thats interesting.
Before rebuilt I got high 20s or low 30s MPG, after the rebuild I got around 20mpg then I put the new fuel pump in and now its around 15MPG max. That kinda seems backwards, shouldn't it get better with better/newer parts?
And I have NO idea how to tell if the ECU is fine, this one oddly doesn't have an LED check light, course, it doesn't have an O2 Either.
Oh heres something else thats interesting.
Before rebuilt I got high 20s or low 30s MPG, after the rebuild I got around 20mpg then I put the new fuel pump in and now its around 15MPG max. That kinda seems backwards, shouldn't it get better with better/newer parts?
And I have NO idea how to tell if the ECU is fine, this one oddly doesn't have an LED check light, course, it doesn't have an O2 Either.
02-08-2011, 12:52 PM
#12
Intrawebz Wizard
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Miles you drove divided by the total fuel you put in, correct?
And I said before, the plugs are a healthy color.
And the CHTS was part of the ohm test and it was at the proper spec.
Maybe my speedometer broke or something and its not keeping proper count of the miles.... As far as I can tell theres nothing mechanically or electrically wrong.
And I said before, the plugs are a healthy color.
And the CHTS was part of the ohm test and it was at the proper spec.
Maybe my speedometer broke or something and its not keeping proper count of the miles.... As far as I can tell theres nothing mechanically or electrically wrong.
02-08-2011, 01:49 PM
#14
More Than Meets The Eye
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I got 17mpg last tank full. And that is having a a cylinder that doesn't burn all the fuel it is given. So if I didn't have that problem, I would be probably getting 20mpg or more.
Okay when you have the AFM open. Barely push on the device that floats up and down. If your car bogs, when you push it a little. You are at the right fuel/air mixture there. If not just move it a few teeth, about 2 or 3 at a time. (clockwise to lean it) Make sure you mark the tooth, before you move it. Another thing, is play with your TPS. Loosen it, and barely move it counter-clockwise, which is the rich side. Then keep the engine at a steady throttle. And slowly move it, until it runs a irregular idle. If that happens, you are to lean. So slowly put it back clockwise. (to the right) Until it smooths out on a steady idle. Hope that helps, and keep us updated.
Okay when you have the AFM open. Barely push on the device that floats up and down. If your car bogs, when you push it a little. You are at the right fuel/air mixture there. If not just move it a few teeth, about 2 or 3 at a time. (clockwise to lean it) Make sure you mark the tooth, before you move it. Another thing, is play with your TPS. Loosen it, and barely move it counter-clockwise, which is the rich side. Then keep the engine at a steady throttle. And slowly move it, until it runs a irregular idle. If that happens, you are to lean. So slowly put it back clockwise. (to the right) Until it smooths out on a steady idle. Hope that helps, and keep us updated.
02-08-2011, 05:41 PM
#15
Intrawebz Wizard
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I didn't miscalculate! I know I didn't, been using the same gas station, same pump (if I can) and I divide the miles I drove by the gallons I used. Isn't that how you're suposto do it?
And wildman, What thing that floats up and down? you mean the sweeper on the track?
And wildman, What thing that floats up and down? you mean the sweeper on the track?
02-08-2011, 08:07 PM
#17
More Than Meets The Eye
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I didn't miscalculate! I know I didn't, been using the same gas station, same pump (if I can) and I divide the miles I drove by the gallons I used. Isn't that how you're suposto do it?
And wildman, What thing that floats up and down? you mean the sweeper on the track?
And wildman, What thing that floats up and down? you mean the sweeper on the track?
02-08-2011, 08:54 PM
#18
Intrawebz Wizard
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Ah ok If I can get the damn cover off I'll check that out
02-09-2011, 01:38 AM
#19
More Than Meets The Eye
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Here is the link to rebuilding the AFM. It will show you how to get it apart, and even adjust the track inside.
https://www.zdriver.com/forums/240z-280zxt-s30-s130-tech-tips-275/js-how-rebuild-your-afm-15277/
Last edited by WildmaN; 02-09-2011 at 01:41 AM. Reason: Needed to add something else
02-09-2011, 06:18 AM
#20
Intrawebz Wizard
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Ah I know how to get the cover off as I've done it before with quite a few AFMs but this one just does not want to open like the others. this weekend I'll toy with it to get it open
Maybe I'll just finish my modded turbo afm and install it lol
Maybe I'll just finish my modded turbo afm and install it lol
02-09-2011, 05:55 PM
#21
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Wait a second...you're talking about running premium in a non-turbo 1980 ZX, right? Wasting your money if so...it was designed to run on 87 & it does just fine on it. I started using 91 in my '82, switched to 87 & got BETTER mpg & no issues. One thing a lot of people forget is the ethanol in gasoline from November-March...nets you about 8-10% less mpg as well.
02-09-2011, 08:45 PM
#22
Intrawebz Wizard
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I was just wondering about the ethanol thing myself the other day when I filled up as there was a new label on that pump I never saw before that said "May contain up to 10% Ethanol"
And I read the owners booklet and it says premium fuel. Sooo ya Maybe I'll check again.
And I read the owners booklet and it says premium fuel. Sooo ya Maybe I'll check again.
