need help getting 12.7 miles per gallon

There's one guy on ebay asking $209 for them but he has make offer option. Always use the offer option and off $50 off or something because they'll almost always counter offer. You can counter a couple times, I think 3 times is the max.
 
FASTLLS said:
^
Good catch.. He is from cali too.. At the moment, there are no aftermarket cats available AFAIK..
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There is, but they usually cost twice as much because they have to go through a certification process that's expensive because the state does it.
 
flowmaster02 said:
Thanks for the help fellas hopefully this will fix my problem.
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What else have you tried?

Engine codes? Cleaned MAF sensor, Tire pressure? Low compression? Are there any other symptoms? Did you feel the tailpipe for abnormalities? Any gas smell at start-up? Check all you filters? Check your fuel pressure? Timing? How long have you owned your LS? What kind of driving do you do? It could be more then one thing.

There's much more to check before just assuming it's clogged Cats.

Edit: oh, have you tried different gas stations? Ethanol is bad for fuel economy too and some stations have to much which will :q:q:q:q fuel economy.
 
im right here with you im getting bad gas mileage as well 2000 v6 ls about 160 miles on a full tank i need a valve cover gasket because oil is leaking into my spark plugs and i had a misfire a while back
 
dnce0589 said:
im right here with you im getting bad gas mileage as well 2000 v6 ls about 160 miles on a full tank
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Holy mother! A lifted suburban does better than that!

Replace the Spark plugs and PCV valve/elbo while you're in there too.
 
Mechanicboy said:
What else have you tried?

Engine codes? Cleaned MAF sensor, Tire pressure? Low compression? Are there any other symptoms? Did you feel the tailpipe for abnormalities? Any gas smell at start-up? Check all you filters? Check your fuel pressure? Timing? How long have you owned your LS? What kind of driving do you do? It could be more then one thing.

There's much more to check before just assuming it's clogged Cats.

Edit: oh, have you tried different gas stations? Ethanol is bad for fuel economy too and some stations have to much which will :q:q:q:q fuel economy.
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There are no engine codes and I usually check my tires often. Every now and then my car make a wierd sound it kind of sounds like its farting. I can't smell any gas and my filters are clean. I haven't checked my compression or fuel pressure though. Where is tha MAF sensor located? As for gas I usually go to 76 and I only put premium.
 
flowmaster02 said:
There are no engine codes and I usually check my tires often. Every now and then my car make a wierd sound it kind of sounds like its farting. I can't smell any gas and my filters are clean. I haven't checked my compression or fuel pressure though. Where is tha MAF sensor located? As for gas I usually go to 76 and I only put premium.
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MAF sensors don't always throw codes when they get dirty. It's located just after the air filter housing. Get the special Mass Air Flow Sensor cleaner from your local auto parts, it shouldn't cost more the $5-7 for a can.

Try using a different gas station, a good common brand. I know 76 is common but that doesn't mean they couldn't be getting a bad supply of gas.

Describe the fart sound better. Is it more of a fart or pop sound? When does it happen, how often and where doesn't it sound like it's coming from? It could be a number of things. I haven't personally experienced all these but here's a short list: blend door, water in gas(I.E. bad gas, use HEET to fix) bad vacuum assist pod(don't think the LS has one), radiator cap bad, or air somehow getting in the radiator, transmission solenoid, and bad catalyst can't cause this.

Also, is your car operating at the normal temperature? Right about the center line?
 
Mechanicboy said:
MAF sensors don't always throw codes when they get dirty. It's located just after the air filter housing. Get the special Mass Air Flow Sensor cleaner from your local auto parts, it shouldn't cost more the $5-7 for a can.

Try using a different gas station, a good common brand. I know 76 is common but that doesn't mean they couldn't be getting a bad supply of gas.

Describe the fart sound better. Is it more of a fart or pop sound? When does it happen, how often and where doesn't it sound like it's coming from? It could be a number of things. I haven't personally experienced all these but here's a short list: blend door, water in gas(I.E. bad gas, use HEET to fix) bad vacuum assist pod(don't think the LS has one), radiator cap bad, or air somehow getting in the radiator, transmission solenoid, and bad catalyst can't cause this.
Also, is your car operating at the normal temperature? Right about the center line?
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The fart sound comes from the exhaust and doesn't happen too often but it has been doing it more often. And yes the car is opperating at normal temp.
 
flowmaster02 said:
The fart sound comes from the exhaust and doesn't happen too often but it has been doing it more often. And yes the car is opperating at normal temp.
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Exhaust leak? Start the car cold and plug the exhaust top with your hands(if you can reach) and see if you can hear exhaust leaking somewhere else. If you hold it long enough the engine should die, if it does then there's a leak but you should hear a leak long before this. While you're there see if one side of the exhaust seems to have more flow than the other.

It could still be a clogging cat, but it would be nice to know for sure before you send a lot of money and find out it wasn't the problem.

Also, I did some research and you must by a catalytic converter that matches your engines EFN, engine family number. This number will be on your emission sticker under your hood.
 
I will keep that in mind for the C.C. Can anybody send a link on how to change the fuel filter? I can't find it right now for some reason.
 
You don't really need a how to for that. It's located behind the drivers side front wheel. You have to remove the plastic wheel well to get to it.
 
flowmaster02 said:
Is the filter plug and go or do I have to do something else to it before I start the car?
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I cycled the key a couple times to build pressure in the system. There will be some air in the system9because it's a return-less system) so if the car stumbles or stalls at first don't worry about it just cycle again and start it.
 
well final changed the fuel filter but haven't been able to drive because I had the coolant reservoir changed and they didn't bleed the system right. So hopefully this will help out with some gas mileage.
 
That definately doesn't sound right. I have a 2004 3.9l (Don't know if it is gen 1 or 2 but I think 2, don't even know how to tell) I don't drive it hard but I don't baby it either. I get 21 in the city and 25.6 on the highway @ ~80mph
 
03 and up are gen2 same size engine but more power do to changes in the engine but I don't think they get that good of gas mileage on the street through. Next I'm gong to clean the Mass Air Flow Sensor and hopefully that will help out some too. Thinking about getting rid of my 20s and getting 17s to drop some weight. I'm trying to do anything I can to get better gas mileage. I don't want to get rid of my car but if I have to I will.
 
flowmaster02 said:
03 and up are gen2 same size engine but more power do to changes in the engine but I don't think they get that good of gas mileage on the street through. Next I'm gong to clean the Mass Air Flow Sensor and hopefully that will help out some too. Thinking about getting rid of my 20s and getting 17s to drop some weight. I'm trying to do anything I can to get better gas mileage. I don't want to get rid of my car but if I have to I will.
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I'm getting close to 380 miles per tank of gas so it must be pretty close. Do you think your injectors are gummed up? If you already answered that I'm sorry I have bounced in and out of this thread a bit
 
flowmaster02 said:
I don't think that they would be I put fuel additives every 3 or 4 months or so.
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I've read too much fuel additives are bad of 02 sensors, not sure if it's true though. I just wish I could help you more but down south is a long drive. ~500 miles

Although, in about late june early july I might be in the oxnard area because my brother is coming home from Afghanistan so I'm going to try to get away from work and head down there is I can. If you haven't solved this problem by then, then maybe We could meet and I could try and help you figure it out.
 
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