Drop of mpg

[danmp]

Hello,

Since november my mpg have dropped really low.


I know winter fuel will drop, but it's my 4th winter with it , and it had never been so bad. Even if i'm very very light on the gas pedal I can't go over 12-13 mpg in city and 15-16 on highway.

I got a rotten egg smell sometime, is it possible that the cat's are gone at 30000 miles?

Can it be the cause of the sudden drop of mpg. Other than that nothing change, same gas, same station, tire etc...

 

[shane1981]

the smell sounds like your cats might be collapsing which would cause a mpg loss it can cause other issue too you might want to get it checked out

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[monteholic]

that smell could also be caused by a rich fuel condition, my first thought would be an O2 sensor or coolant sensor

 

[whetrick1]

Could be the cats because usually when a sensor starts giving you problems it will throw a code. And the cats could be restricting the exhaust flow.


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[liftedgm1982]

You're obviously burning more fuel than usual. I'd also guess a faulty O2 sensor without looking around at it personally. No codes on dash? Has it thrown a code at all recently? I'd scan it just to be sure.
This is the reason I calculate fuel economy at every fill up. It's a good indicator if your engine is running right.


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[Mbrigh3]

Thats about what I get... I usually get 12-13 Mph in the city and 16-18 on the highway.

 

[danmp]

No i never got any code.

I hand calculed few times, and the truck was almost right every time with minimal error.

I will take it to the dealer, hopefully they will found something.

 

[liftedgm1982]

No i never got any code.



I hand calculed few times, and the truck was almost right every time with minimal error.



I will take it to the dealer, hopefully they will found something.

I would. Just do yourself and the dealership a favor and try to write down your hard numbers of fuel economy from before/after you noticed the drop. Also any signs/symptoms that you can think of that may be associated. This might help your service department get an idea of where to start, as well as not just pass you over as a guy just complaining about fuel economy in his big heavy truck[emoji1303]


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[danmp]

It's that bad

 

[danmp]

I would. Just do yourself and the dealership a favor and try to write down your hard numbers of fuel economy from before/after you noticed the drop. Also any signs/symptoms that you can think of that may be associated. This might help your service department get an idea of where to start, as well as not just pass you over as a guy just complaining about fuel economy in his big heavy truck[emoji1303]


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Anyway I had to go there. I probably have a manifold bolt problem. And I don't know if it can be related, but after a oil change i have some time hard knocking, like this truck : https://www.youtube.com/watch?v=0CFXKOlyxZo

 

[liftedgm1982]

Anyway I had to go there. I probably have a manifold bolt problem. And I don't know if it can be related, but after a oil change i have some time hard knocking, like this truck : https://www.youtube.com/watch?v=0CFXKOlyxZo

Not really sure what that sound is, but I'd say the dealership would be a priority if it were mine.


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[whetrick1]

Yes I agree the dealership would be my first choice.


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[jljbtm]

If you have an exhaust leak then it is also sucking in air into the exhaust. The down stream 02 sensor then sees a lean fuel mix and the computer then is compensating by adding more fuel.

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[RAMTRPR]

What's the best way to test for exhaust leak? I have headers and checked all bolts are tight. Checked also the header to cat and that seems good but when driving I still hear what sounds like exhaust from the drivers side. Any suggestions?


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[hemipower95 2.0]

It's that bad

Are you french

 

[shane1981]

What's the best way to test for exhaust leak? I have headers and checked all bolts are tight. Checked also the header to cat and that seems good but when driving I still hear what sounds like exhaust from the drivers side. Any suggestions?


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headers are very noisy you can wrap them and it will quieten them down but if it is an exhaust leak then get a piece of rubber hose 3/8,1/2 etc and put it to your ear and probe around and it will show up . i had this same issue i killed myself trying to find a leak and eventually told myseif it was lifters 3 weeks agi i wraped my headers and now the truck is super quiet

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[jljbtm]

I had a pin hole in the left header on my Hemi magnum had to remove it and had the hole welded then reinstall with new gaskets. It sounds like Ike the "hemi tick" but a little Louder. Mostly heard at a toll booth or drive thru when the tick sound is bouncing back at you. You can also look for soot.

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[jljbtm]

Any exhaust leaks will spoil your tune

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[RAMTRPR]

Time to start leak hunting and wrap my headers


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