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It looks like I'm getting around 200-230 miles per tank (roughly 14 gallons). I don't want to do the math, but that's not all that good. I do a lot of around town driving, and I'm heavy on the gas, but it seems to me that it was better a few months ago. So I've narrowed it down to several options, and you all can let me know what you think.

1) Factory O2 sensor..... never been replaced, came with the engine, could be 20 years old for all I know.
2) Throttle Position Sensor..... I don't think this would affect milage, but it also is old, came with the car, probably original also.
3) AFM needs to be "modded"........ sometimes it smells like my car is running rich, mostly right after start-up
4) Cold start injector is funked up....... could also be responsible for why my car is so hard to start when it's cold and the "coughing".... but most of that is for another post.
5) Timing is off
6) Plugged cat......... 20 years old and nasty, weighs ~20 lbs.

Any input? BTW I'm running a 5M-GE on 5M-E electronics, and NO I'm not swapping in a whole wiring harness, the car runs just fine.
 

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i have similar troubles with fuel consumption, so im interested in answers as well.

I have been running 96octane tho, so maybe i should be running it on 98?

im not too concerned as in a few months ill be getting a more efficent motor: read lexus 4l v8

However i get reasonable mileage on the open road, but still not 500ks like a mates ma61.

maybe fuel filter needs replacing?
 

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Thats not too horrible for around town mileage. Thats about what mine get. I get about 12-18 mpg usually and I romp on it a lot.
 

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Discussion Starter #4
SilverMk2 said:
Thats not too horrible for around town mileage. Thats about what mine get. I get about 12-18 mpg usually and I romp on it a lot.

hrmm, ah........ cursed heavy foot. I need to look into some helium shoes. So a new O2 sensor probably wouldn't be worth my money then eh.....
 

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I usta get about 15 mpg and have very little power up hills. I thought it was just an old engine because I just got new plugs, wires, distributor cap and it was still like this. Then, I took it to my mechanic to do the timing. He did the timing and had to replace the fuel filter. When he gave it back to me, I had a completely new car. I've already put about 2,000 miles on it since this and I get insanely good gas mileage (22 city, 26 hwy) and I have tons of power.
 

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lots of things can cause bad gas milage...

- running rich
- clogged injectors
- bad or disconected 02
- blockages in the intake or exhaust system
- over tightened belts or seized brake calipers
- dirty air filter
- low compression
- bad spark
 

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check your error codes. if it's an o2 sensor it'll give you the error code but it isn't one of those things that turns the check engine light on.
 

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Recently fighting same problem-Last tank before Seattle Nats 25 MPG-After putting 2-1/2 Inch exhaust on down to 20 MPG-Back up to 23+ this tank with new air filter-Might have just been air filter on mine-Mike
 

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My 86 gets 21-22mpg mostly freeway with driving 75-80 mph.
 

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Oxygenated fuel

Could be the switch to oxygenated fuel. The government likes to change over to this fuel when cold weather arrives. The fuel is supposed to burn cleaner (that's what they say). Kind of silly, cleaner burnig, but greater fuel consumption, more times to the pump, more burning of fuel, greater emmsions. Its a joke.
I believe the addative to the fuel is called MTBE which creates the oxygenated fuel mixture. It's poison!!! Gets in our water!!! Although MTBE might be banned from certain states (not currupt ridden NJ).
My $.02.

Al
 

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I am getting about 19 when I used to get maybe 24. I am not sure if the fuel filter has EVER been relaced. What brand should I purchase?
 

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CarFreek said:
Recently fighting same problem-Last tank before Seattle Nats 25 MPG-After putting 2-1/2 Inch exhaust on down to 20 MPG-Back up to 23+ this tank with new air filter-Might have just been air filter on mine-Mike
I had this exact same problem after I switched to my 2.5 system. I traced the problem to a heavy right foot. The foot had gained weight due to the pleasures the ears was experincing which spread to a big goofy grin on the face. Other symptoms included anoyed neighbhoors and nasty looks from old ladies.

Still dealing with the problem, but "restraint" has helped immensly with increasing my gas milage, but it can't seem to be found anywhere when the wife isn't in the car.

:3gears:
 

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My poor mileage was due to a pair of rear defective calipers. Once I replaced them I went from getting 380 kms to the tank, to 500. The way you can tell is if your rims are hotter than normal after a 10-15 min run.

Hosam
 
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