Poor Fuel Economy

10 MPG average is horrible unless you drive WOT a majority of the time.
If not, the exhaust fumes would be awful at idle.

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Hey y'all, sorry it's been so long. I totally forget about this thread, but it's been several months that I've had my Marty tune and I absolutely love it. I manage 15 mpg in my area in most of my tanks, although I still get as low as 10 sometimes, but I suspect that's just from the geography.

All is good, and thank y'all for your suggestion of getting a Marty tune. He does good work, and my car feels so much faster.

Thinking of maybe sticking some 4.10s in it if the fuel eco wouldn't suffer too much. Thoughts?
 
baloneyhomie said:
Hey y'all, sorry it's been so long. I totally forget about this thread, but it's been several months that I've had my Marty tune and I absolutely love it. I manage 15 mpg in my area in most of my tanks, although I still get as low as 10 sometimes, but I suspect that's just from the geography.

All is good, and thank y'all for your suggestion of getting a Marty tune. He does good work, and my car feels so much faster.

Thinking of maybe sticking some 4.10s in it if the fuel eco wouldn't suffer too much. Thoughts?
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You'll lose maybe 1 or 2 MPG. Well worth the 4.10's.
 
If you are really getting 15 mpg's or lower in regular driving you still have a problem. Your profile says your MM is NA. I'd take the car to Mo's and have them go over it to find out why your mpg's are so bad. You should be getting low to mid 20mpg's.
 
Mr. Man said:
If you are really getting 15 mpg's or lower in regular driving you still have a problem. Your profile says your MM is NA. I'd take the car to Mo's and have them go over it to find out why your mpg's are so bad. You should be getting low to mid 20mpg's.
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It's effectively stock. I assumed 15 was normal for NA but I guess not. My old '09 SAP CVPI with 3.27s managed a solid 20-25 in my town.

Luckily I live about an hour away from Mo's; I assume I just gotta give his shop the call and let him know what's up?

Now I'm getting a bit worried, considering how good of shape this particular car is in :P
 
My first Marauder was stock when I bought it. My first mod was 4.10's and a tune. Best bang for the buck!
 
baloneyhomie said:
It's effectively stock. I assumed 15 was normal for NA but I guess not. My old '09 SAP CVPI with 3.27s managed a solid 20-25 in my town.

Luckily I live about an hour away from Mo's; I assume I just gotta give his shop the call and let him know what's up?

Now I'm getting a bit worried, considering how good of shape this particular car is in :P
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Make the call to Mo's. I'm getting 24-5mpg on the freeway and 19-21mpg putting around town. Be interested to hear why your mileage is so bad. I'm making an assumption you are not wide open everywhere you go.
 
Mr. Man said:
Make the call to Mo's. I'm getting 24-5mpg on the freeway and 19-21mpg putting around town. Be interested to hear why your mileage is so bad. I'm making an assumption you are not wide open everywhere you go.
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Nope. I went a full tank going full grandpa-light-on-the-pedal once or twice and still only managed 15. I drive it mildly spirited and I still (sometimes) get as low as 10. Usually 12-15 though.

Who would have thought this thing managed the same fuel economy of my three ton hightop Chevy conversion van with the 350.

No worries though, I’ll shoot Marty a call once I’m free this afternoon.
 
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No way should you be getting such poor gas mileage. I would be very curious to hear what Marty finds. I am guessing if you are calculating your mileage correctly I would check: brakes possible bad calipers. Pull all spark plugs they will give you a world of info. Maybe your injectors are leaking, bad or wrong stall speed converter or maybe cams have been advanced either way your car will be in the best of hands.
 
burt ragio said:
No way should you be getting such poor gas mileage. I would be very curious to hear what Marty finds. I am guessing if you are calculating your mileage correctly I would check: brakes possible bad calipers. Pull all spark plugs they will give you a world of info. Maybe your injectors are leaking, bad or wrong stall speed converter or maybe cams have been advanced either way your car will be in the best of hands.
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Just checked the plugs in fact. They look good, ditto for the coils. I have yet to service the brakes or calipers since my purchase of it last year although it doesn’t feel like anything is wrong on the brake side of things.

I gave him a call and left a voice message and let him know what’s up. Will update y’all accordingly.
 
Probably just some lazy oxygen sensors.

But don’t believe every claim you here. When mine was first purchased the best I could get was 21.5. This was zero traffic, speed limit 45 for five miles, then expressway for fifteen, and finally another fifteen or so of country roads at 55 with maybe four stop signs so definitely not city but a mixture nonetheless.

Then I put on the Trilogy I used to have and mileage actually went up one from tuning I suppose.

Finally a best ever of 23.5 once I had a dyno session and custom tune.

It’s been a long road down to single digits since. [emoji16]


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It's entirely possible you are right - I'm also a stubborn fella and I would really like to think I could squeeze more MPGs out of this 2 ton hunk of steel.


At worst, I'll be tuning up the crap outta this car, so maybe not a complete fool's errand. :P
 
I spoke to Marty a week ago and he suggested some stuff. I've already done the first two suggestions, and the third was swap the fuel filter. (The filter on my car is 5 years old)

The filter only has 5kish miles on it, but it's an 8 dollar part from Rockauto and OEM so worth a shot. I hope to replace it and maybe even crack open the old one and see how it looks. Will update more, thanks y'all.
 
baloneyhomie said:
About an hour drive from where I live. I'll try and put some time aside to give them a visit this weekend. That being said, what's the issue with the Reinhart tune, or is it more of the fact that Mo's Speed Shop is just better?
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Be sure to call first, don't just show up. Busy as hell shop, it's based on appointments not walk ins... it's not Autozone...
 
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