Mpg

[akcamaro02]

I just recently replaced my fuel pump and filter and ever since then i get like 15 MPG, and my last tank, i didn't get on it at all and got 14.8 MPG and this tank i got 12 MPG...it used to get 19-20MPG and I was wondering does anyone have any ideas of why I would be getting so bad of MPG now?

[pace2006]

Re: Mpg

Could be a number of things... searching might be able to clear up a few options. Other than that, anything else noticeable? Fuel smells? Hard to start? Clogged cat?

[akcamaro02]

Re: Mpg

It has a delayed start in the morning but I'm sure that's due to the fact that the engine has sat outside in 30 minus degree weather so it's just a little cold...no fuel smell though...How do you determine if the cat is clogged?
I've ran through everything I thought it could be, I checked the tire pressure....rear tires are 36-37psi...fronts 34-35psi...so tire pressure is good, I drove around 2500RPMs and less to conserve gas...the highest gas mileage I've gotten since the fuel pump/fuel filter replacement is 16.1 and that's because of the highway miles I had on that tank...it's a stock v6 and somehow it went from high 18s, 19s in MPG to 16MPG and everytank has been getting worse...
i bought some fuel system cleaner stuff from autozone that's supposed to clean out the tank, fuel lines, filter, and all the way up to the injectors.

[whitdog54]

Re: Mpg

im getting like 15mpg right now......exhaust smells rich, but im not throwing codes? any help would be great as well

is it just that my car hates the cold? it happened as soon as my windows started getting frosty in the morning....

[cam98aro]

Re: Mpg

that is a very high tire pressure reading.. especially in the cold, i would defiantly lower them

[kristen]

Re: Mpg

how are your injectors, plugs and wires?

[whitdog54]

Re: Mpg

I think my problem is a crap 02 sensor.....it stopped throwing a code, but I think thats still it.

[Leonard 3.8L]

Re: Mpg

yea i was going to call 02 sensor

[Rob Bell]

Re: Mpg

O2 sensors can go bad and not throw a code. As they age they start slowing down their switching speed and their voltage readings can become marginal, but not out of the range where it would cause a code to be thrown. So then you start running rich or lean with no codes. This is where you need a real-time scanner so you can see what they are actually doing.

[akcamaro02]

Re: Mpg

well when i first bought my car in may of this year, i had it inspected and the drive belt was cracked and i've never had it replaced but im going to in a couple of days because i've had some voltage issues and the alternator issues and climate control issues and i think my belt is slipping but do u think that would affect the MPG?? oh and within the first 2 weeks i had my car 1 of the front O2's broke and was replaced but only one of the fronts were replaced and i talked to some f-body people and they suggested to replace both but my warranty wouldn't cover both, do u think that O2 might be failing also? btw, i filled up today, 13MPG--stock V6=terrible

[whitdog54]

Re: Mpg

O2 sensors can go bad and not throw a code. As they age they start slowing down their switching speed and their voltage readings can become marginal, but not out of the range where it would cause a code to be thrown. So then you start running rich or lean with no codes. This is where you need a real-time scanner so you can see what they are actually doing.

What should I be looking at on a real-time scanner? I have a friend with one.

[zz_camaro_zz]

Re: Mpg

have you checked to make sure its not leaking from a fitting somewhere? you wont always smell it when that happens.

[whitdog54]

Re: Mpg

Yea, no leaks, I just recently tightened all my flanges and everything. I have locking nuts on the header bolts...maybe ill check those again anyways.

Ill try to get some readings from a scanner today.

[cam98aro]

Re: Mpg

What should I be looking at on a real-time scanner? I have a friend with one.

you should be able to use the scanner to give you the true MPG your car's computer is calculating if you have obd2

a great little tool is a scan gauge 2.. its only $170 and you can do a bunch of stuff with it, check codes, get a bunch of gauges, get a trip function, its pretty neat, they have a website, just search google for scan gauge.

its worth the price IMO

[Rob Bell]

Re: Mpg

Yeah I would love to get one of those Scan Gauges, they look pretty cool. As far as watching the O2's, find out first what the specs are supposed to be, like voltages and switching speeds. Then watch the O2's on the scanner and see if they are working as they should be.

Even if an O2 is not covered under warranty, I would replace it anyway. They are not real expensive. But they are probably the main thing that tells your computer how to run the car. If one went bad, the other is probably not far behind.

13 mpg is pretty bad, I'm kinda surprised you aren't smelling almost raw gas from the exhaust.