installed new catco cat.update. need help 1-22-08 - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 01-22-2008, 02:22 PM   #11
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update- 1-22-08

o.k so i have tested the new cat and i am getting way better throttle response, way better power and low end torque, and im not getting the funny rotten egg smell anynore either and its not making the clicking noise when i turn the car off..(old cat did)

BUT

i did notice im not getting the mpg i expected.. in fact im not getting close to that..

what i did before i changed the cat was filled my tank all the way till the pump stopped then reset the trip meter and drove the car untill the low fuel light came on.
i was getting 200 miles on a full 18 gallon tank..

and now with the new cat i filled the tank 2 times and did the same thing.
and the foirst tank i only got 247 miles on a full tank and the second full tank just ended yesterday and i only got 251 miles on my trip meter.?

i cant calculate my mpg but this is not what i expected to see..

can anyone help me with what could be causing this poor milage..?

and could the fuel filter have alot to do with it.? thanks i appericate it...
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Old 01-22-2008, 02:34 PM   #12
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We'd need to know how much gas was put in each time. Fuel mileage can be roughly figured though. Assuming you had filled your tank and reset the trip at that time, on your next fill up, fill it up completely. Then, take the number of miles you just went and divide it by the number of gallons you just put in. That'll give you a very good idea.

It does look like you've gone up in mileage though from before, but there still might be other things. The computer might not be re-calibrated yet for the good cat. The O2 sensor could be on the way out, there could be another issue the cat covered up, etc.

I'd say give it some time and see. +50 miles is a decent improvement of 2-3 miles per gallon.
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Old 01-22-2008, 02:35 PM   #13
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Is it cold? Winter blend gas will make your mpgs go crap. Is your tires properly inflated? Cold air is more dense thus the air in the tires will shrink a bit causing loss of psi.

And more importantly, how do you drive?
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Old 01-22-2008, 03:08 PM   #14
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Quote:
Originally Posted by fuelforthesoul1999
Is it cold? Winter blend gas will make your mpgs go crap. Is your tires properly inflated? Cold air is more dense thus the air in the tires will shrink a bit causing loss of psi.

And more importantly, how do you drive?
tires are good, yes its cold its freezing here in pa.
and my o2 sensor should be good as its not black, invact it still looks silver like when you buy it. i believe i replaced it about 7 months ago.

and what do you mean exactly how i drive.?

i drive about 30 mph thru town. speed limit 35-25 mph in places.
i drive about 70-80 on the highway which is rarely
i also have 60-70 pounds of music in my car.
and most of the time its me , my wife , my 4 yr old and my 1 yr old,



did i just answer my own question.. damn wife and kids they are slowing me down.
music has too stay

but besides the weight in the car. is my mpg as bad as im thinking it is.?
what is it really.

and i fill up my tank untill the pump stops by itself which is around $50 due to gas price
then i drive it untill the low fuel light comes on.
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Old 01-22-2008, 03:14 PM   #15
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I mean, do you drive aggressively? Do you floor it or give the pedal some good mushing or you drive like there'* a egg under the gas pedal?

Driving habits will play a big factor.
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Old 01-22-2008, 03:15 PM   #16
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Quote:
Originally Posted by fuelforthesoul1999
I mean, do you drive aggressively? Do you floor it or give the pedal some good mushing or you drive like there'* a egg under the gas pedal?

Driving habits will play a big factor.
well i definetly dont drive like there'* an egg under my pedal.
but i dont floor it and make the tires screech either...
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Old 01-22-2008, 05:05 PM   #17
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next time you fill up, write how many gallons it too, and how many miles you went and post them up.

The low fuel light is not necessarily the end of the tank. You probably only use like 12-16 gallons at most, Assuming you used 12 gallons to go 251 miles, you are around 21 mpg, which is still a little low I believe for your year. I know my 93 regularly does 22-24 mpg.
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Old 01-22-2008, 06:44 PM   #18
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Quote:
Originally Posted by JimmyFloyd
next time you fill up, write how many gallons it too, and how many miles you went and post them up.

The low fuel light is not necessarily the end of the tank. You probably only use like 12-16 gallons at most, Assuming you used 12 gallons to go 251 miles, you are around 21 mpg, which is still a little low I believe for your year. I know my 93 regularly does 22-24 mpg.
o.k i will top off my tank again tomorrow as its running kinda low and should set the low fuel lightoff and ill ride it out.. then ill post back up with how many gallons i put inside and how many miles i get bytime the low fuel light comes back on..
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