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View Full Version : Bad MPG. What else am I missing?



Hazwan
07-04-2012, 10:17 PM
I know the basics, but just making sure what else I'm missing here :(

I get about 15.7mpg city driving.. like a grandma. That IS bad. How do I know that my carb is bad? What else that I could do, list out even the basic shit that I probably have missed.

Also, I think I'm burning oil a little if not much. Does this effect the gas mileage by whole bunch?

2oodoor
07-05-2012, 01:36 AM
For peace of mind, do a compression check first.
If the carb is dumping too much fuel you should see sooty spark plugs .
You can also check the cam timing then too because the motor will bw easy to turn while the plugs are out.

Hazwan
07-05-2012, 05:10 AM
For peace of mind, do a compression check first.
If the carb is dumping too much fuel you should see sooty spark plugs .
You can also check the cam timing then too because the motor will bw easy to turn while the plugs are out.

I'll give them a check (Y)

Also, does this look worn to you?
http://img152.imageshack.us/img152/8615/62913140.jpg

There are no cracks or anything but I noticed slight groove to them. Same goes with the rotor.

http://img339.imageshack.us/img339/4253/60475042.jpg

I don't remember when was the last time they are all replaced but probably loooong time ago even before my dad gave the car to me :facepalm:

I know I could just replace them all (including my spark plug cables) as a preventative maintenance item(s) but I'd rather not waste money on something that still work perfectly fine.

2oodoor
07-05-2012, 06:04 AM
You are still using ignition breaker points?
My roommate had a 1 gee that I drove for a long time and one thing I remember is those points being a PITA due to a worn distributor.
I also discovered that the cap and rotor need to be a matched up pair, same brand, etc. on those or it can cause problems.
If there are grooves then yes that can cause someresistance in the secondary ign, which in turn can burn up some points, cause misfires or cross fires.

EDIT, I see the reluctor wheel now, it isn't breaker points is it. I was looking at the two wires, and then what looked like an adjusting screw.

Hazwan
07-05-2012, 06:09 AM
Yeah its electronic. Does the groove means anything to an electronic dizzy?

Buzo
07-05-2012, 06:58 AM
That ugly fuel mileage is mostly caused by the carburetor and/or 1 (or more) bad spark plugs/wires.

So the easiest check would be to make sure all your spark plugs are firing.
Then go for that carburetor. It can be as easy as a jammed choke plate, to a need of full refurbishing.

Hazwan
07-05-2012, 02:50 PM
I'll give the spark plug and wires a check.

I had the carburetor rebuilt last year and unless I did something horribly wrong, I don't see how it could be bad haha

Dr_Snooz
07-05-2012, 07:07 PM
I had the carburetor rebuilt last year and unless I did something horribly wrong, I don't see how it could be bad haha

You rebuilt a Keihin? I think Keihin is Japanese for "worst carb ever."

How does the car run?

Hazwan
07-05-2012, 07:25 PM
You rebuilt a Keihin? I think Keihin is Japanese for "worst carb ever."

How does the car run?

LOL mine is the simple 2 barrel stuff without the CVCC and the emission crap so I think I'm good. I think. Car runs fine except for rare stumble/hesitation when going off a speedbump. Idk why or how to explain.

Anyway I went ahead and replaced the cap, rotor and wires just because they are cheap and old. Car idles super smooth now o.O Except my tach kinda jumps every once in a while during idle. I don't see how replacing all these items would cause the tach to jump around randomly? its like idling around 750 rpm smoothly then the tach would go 1200 back to 500 then goes back to 750.

Dr_Snooz
07-06-2012, 08:54 PM
I can't speak for your car, but my jumpy tach problems finally went away for good and all when I replaced the ICM. It could also be a bad coil.

lostscotiaguy
08-02-2012, 07:36 PM
Wait...did someone say keihin here? (Covering my ears) LA LA LA I CAN'T HEAR YOU! Seriously though, i'd give some pointers but it looks like you've got your bases covered. I agree with Dr. Snooz on that coil, but the other thing re:carb, does it smell like it's running rich? As much as I love/hate carbs, I've been SO tempted to weld a bung into my exhaust just to hook up a F/A sensor/gauge. Now if only I had the tools, the knowledge, the money, the.....

Hazwan
08-03-2012, 04:15 AM
Wait...did someone say keihin here? (Covering my ears) LA LA LA I CAN'T HEAR YOU! Seriously though, i'd give some pointers but it looks like you've got your bases covered. I agree with Dr. Snooz on that coil, but the other thing re:carb, does it smell like it's running rich? As much as I love/hate carbs, I've been SO tempted to weld a bung into my exhaust just to hook up a F/A sensor/gauge. Now if only I had the tools, the knowledge, the money, the.....

You really do hate keihin aren't you hahah

But yeah its really hard to tell from the smell since my engine burns oil and the exhaust smells like... well, oil?

ghettogeddy
08-03-2012, 11:01 AM
have you tried different brands of gas or do you just use w/e is cheaper? i notice a difference in my elantra between 76 and beacon almost 5 miles per gallon

2ndGenGuy
08-03-2012, 01:26 PM
I say get one of those 2000's era carbs from one of those Malaysian cars you've got over there, and make an adapter plate! You can do eeet!

Hazwan
08-08-2012, 07:06 AM
I was just wondering if my brake booster is actually leaking since I could hear it hissing when the engine is running? This too would probably explain why I could never get the mixture 100% correct.

So yeah is a hissing brake booster normal?

2ndGenGuy
08-08-2012, 08:30 AM
Definitely should not be hissing. I would replace it! And yes, it would explain your mixture troubles.

2oodoor
08-08-2012, 08:37 AM
Make sure that isn't just the check valve hissing, the piece in between the hose and the actual body of the booster. A valve would be an easy fix.

Hazwan
08-20-2012, 01:15 AM
I should add that I lose the booster function right after the engine dies too. I know its not supposed to do that and thats the check valve's function right?

I'm gonna have to give the check valve a.. check.

Also, replacing my dizzy cap, rotor and wires got me 22.5mpg of city driving, which I don't think its too bad? Help me squeeze out 3 more mpg please!!

1GCustomAccord
08-20-2012, 09:08 AM
Did you check your vacuum advance?

Hazwan
08-21-2012, 05:30 PM
How do I check them properly? They appear to be moving fine but idk if they actually works properly under vacuum.

2geeSEi
08-21-2012, 10:28 PM
Does your advance have one or two hoses going to it?

Hazwan
08-22-2012, 03:06 AM
Just one hose.

Buzo
08-22-2012, 08:12 AM
...
Also, replacing my dizzy cap, rotor and wires got me 22.5mpg of city driving, which I don't think its too bad? Help me squeeze out 3 more mpg please!!

Good to hear that it improved from 15 to 22!

How is your choke working in general?

The choke is usually needed for the cold mornings only, but during the day we don't need that much fuel to restart the car.

An easy way to check if you have choke problems is if your car restarts very rough and you need to accelerate it to control it.

A restart means being driven for some time, then stop the car and attempt to restart it into the next 5-30 minutes.

2oodoor
08-22-2012, 08:33 AM
That does sound like a check valve leak, but I would still check the inside of the car side of the booster to see if that is hissing.

You can check the overall basic function of the advance system by putting a timing light on the marks (crank pulley or flywheel) and watch the marks move out of sight as you raise the rpm.
If you have a advancing timing light you can zero it out and match the light to the TDC mark and the display will read out the amount of advance.
I don't know if the 1gen has vaccuum advance on at idle like the 3rd gen or not??
If it does then you can pull the hose on the dizzy at idle and the rpm should change if not may even stall out the engine. That would mean it is working.

2geeSEi
08-22-2012, 09:03 AM
If the advance has only one hose, it will not be on at idle. The easiest way to check it is to take off the hose and put a hand vacuum pump on it. Start the car and watch the timing when you put vacuum on it. The timing should advance and should hold the vacuum.

Hazwan
08-23-2012, 08:45 PM
Good to hear that it improved from 15 to 22!

How is your choke working in general?

The choke is usually needed for the cold mornings only, but during the day we don't need that much fuel to restart the car.

An easy way to check if you have choke problems is if your car restarts very rough and you need to accelerate it to control it.

A restart means being driven for some time, then stop the car and attempt to restart it into the next 5-30 minutes.

I actually had my choke deleted so its not gonna be a problem.

I'll recheck the booster check valve again and I'll try to find a hand vacuum pump too.

Civic Accord Honda
08-24-2012, 01:13 AM
Good tip for not needing a vac pump. long hose. put in mouth. suck .tip i learned a long time ago for testin EGRs and stuffs

Hazwan
08-24-2012, 03:01 PM
Good tip for not needing a vac pump. long hose. put in mouth. suck .tip i learned a long time ago for testin EGRs and stuffs

I might give that a try :D Good tip!

2geeSEi
08-24-2012, 07:24 PM
It's kind of tough to watch your timing mark while doing that though and tell how long the vacuum is holding. My hand vacuum pump is one of the most useful tools I have ever bought. You can get them for $25-$30. Great for testing all kinds of things, and you can bleed brakes without a helper. I have even used it to start siphoning gas without worrying about getting it in my mouth.

Hazwan
08-30-2012, 04:44 AM
Haven't got around testing the vacuum advance but I've got myself an EK booster+master cylinder for cheap so I figured I'll just replace them :D Updates soon.

2ndGenGuy
08-30-2012, 08:31 AM
You could try disconnecting the booster and just running with manual brakes and see if that helps. I had to do that on mine, couldn't stand the hiss and the inconsistent brake pedal.

POS carb
10-05-2012, 02:31 PM
a hissing brake booster is blown and causes a vacuum leak
the check valve is there so you still have power assist after full throttle, it will not stop the leak
another thing to consider:
if your overall wheel size is bigger and you are calculating mpg by your odometer you will have lower mpg because you have actually traveled farther than your odometer indicates fyi

Hazwan
10-05-2012, 03:57 PM
Replaced my booster few weeks back and the hissing is gone as well as gaining around 2-3 MPG.

Man I never considered the wheel size now. Does anybody know what the exact size of the stock 1g tires? I know its 155-13" but nobody listed the profile (N)

Dr_Snooz
10-05-2012, 07:23 PM
On the '76, the tire size was 155 SR 13, which means the sidewall is 100, I guess. The tire size changed by '81 though, and I don't know what it was.

Hazwan
10-05-2012, 07:29 PM
I guess I'll check the speedo with my GPS to confirm if its accurate or not.

POS carb
10-09-2012, 07:19 AM
you need to check the odometer too, the speedo is probably off a bit if you pulled the needles to paint them orange.
The odometer is usually pretty accurate if the tire size is right

Hazwan
10-13-2012, 11:31 PM
you need to check the odometer too, the speedo is probably off a bit if you pulled the needles to paint them orange.
The odometer is usually pretty accurate if the tire size is right

OMG yes you are right! I just got around checking the exact odometer reading compared to my GPS and its about 0.14km off per km. Which the odometer would read 14km less if I travel 100km according to the odo. It would be 114km exactly according to GPS.

Looks like I'm gonna have to recalculate my MPG again with my GPS (Y)

POS carb
10-26-2012, 02:33 PM
Glad I could help.
so now, when you check your mpg by your odometer, just multiply your kms traveled by 1.14 and divide by gallons and it should be right