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Baaaaaad Gas Mileage


ardavis78
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I've got a '96 Pathy w/ approx. 125,000 miles on it. My gas mileage never was that great, but I am recently getting about 10 -11 mpg. I just replaced my plugs and air filter(K&N). I thought that would make a big difference because the gap was approx. .080 on the old plugs(new are gapped @ .040) ,but nothing. I know about the oxygenated gas in the winter, but this is awful. My check engine light isn't on and the truck runs very well. Any hints maybe? I even installed manual hubs too. Any little tips or tricks would be appreciated. Thanks!!

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A bad O2 sensor will sometimes not set a CEL.

 

Another possiblity is that the coolant temp sensor for the EFI has died. This won't set a CEL either.

 

Agreed! In my 98 I replaced the coolant temp sensor at about 90K and got 2 mpgs back....I was really excited about this maint. because it was sooo easy and about $24. I would look here first. If you have the loot replace all 4 O2 sensors and never think about it again, or for at least 85-100K.

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I'm kind of in the same boat.

 

But I did: plugs, wires, fuel/air filter, all 4 O2 sensors, PCV valve, and seafoam, and still get ~230 to a tank which equals ~12MPG but with the 31s I am running I don't know what the actual mileage is. I'm guessing ~13MPG. I guess the next things I can try is cleaning the MAF sensor and replacing the coolant sensor. Where is it located? I'm guessing on the lower part of the radiator?

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I'm kind of in the same boat.

 

But I did: plugs, wires, fuel/air filter, all 4 O2 sensors, PCV valve, and seafoam, and still get ~230 to a tank which equals ~12MPG but with the 31s I am running I don't know what the actual mileage is. I'm guessing ~13MPG. I guess the next things I can try is cleaning the MAF sensor and replacing the coolant sensor. Where is it located? I'm guessing on the lower part of the radiator?

 

 

The 2 prong coolant sensor I changed was on the thermostat housing. 19mm wrench is all you need. Cost bout 20 bucks.

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  • 3 weeks later...
The 2 prong coolant sensor I changed was on the thermostat housing. 19mm wrench is all you need. Cost bout 20 bucks.

 

 

My gas mileage has also gotten really bad lately. My check engine light goes on and off so I wasnt sure what the deal is. A lady I work with has a 99.5 and she is having the same issues. Her husband is a mechanic and he thinks its the 02 sensor. I was gonna hold off doing anything until spring, but Ill be broke by then the way its going. I figured the sensor would be super expensive because they are on my M3, well I guess everything is expensive on it, but you guys are making it sound pretty cheap.

 

So what else should I get? Coolant sensor? I was going to change my spark plugs until I saw all the stuff I have to remove to get to them. Is replacing them as big a PITA as it looks? Any DIYs?

 

Also, can I get these parts from an auto parts store like auto zone or do I need to go to the dealer?

 

Thanks in advance.

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Replace:

 

O2 sensors with good ones (Denso)

Plugs & wires (use the supplied kit under the rear seat makes it very easy, even #6)

PCV valve

Air filter

Fuel filter

Coolant temp sensor

Clean the MAF sensor

Seafoam the the intake, fuel, crankcase

 

I bought my O2 sensors & PCV valve online because they were a lot cheaper than in the store. www.autopartswarehouse.com

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Hi!!

could you answer this questions?

 

1. what is MAF?

2. Where do i find MAF?

3. How can i clean MAF?

 

Thank you very much!!!!

 

1 - Mass Airflow Sensor

2 - it's a plastic box that is connected to your air cleaner box.

3 - Should be an article about it on here. Just need some electrical contact cleaner and some q-tips.

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