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Author Topic: Lost MPG after custom tune  (Read 4101 times)

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mxzretta

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Lost MPG after custom tune
« on: November 22, 2015, 17:03:29 PM »

Had a custom tune done and I went from 15 mpg down to 11 mpg. My truck has had the cats gutted so it was always throwing 420 and 430 codes. I had him make it so it wouldn't throw the codes. Wondering if the computer is not getting any readings from the o2 sensors thus causing the poor mileage. Tune was dome with EFI live. Thanks for any help
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Randy

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Re: Lost MPG after custom tune
« Reply #1 on: November 22, 2015, 17:48:50 PM »

P0420-P0430 only tell that the converters are not working properly, turning those sensors readings off does not affect the air fuel ratio.

The questions are???

1. Have you been driving it like you stole it checking the performance after the tune.
2. Who tuned it.
3. Was it a performance tune or a mileage tune.
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mxzretta

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Re: Lost MPG after custom tune
« Reply #2 on: November 22, 2015, 18:56:28 PM »

When I first got the tune of course I drove it like I stole it. But that was over a month ago. Drive like I always have. The tuning was done by a very reputable tuner up here in Edmonton. He mainly does diesel tunes. As for performance or mileage tune never asked. He rode with me made some changes flashed it and had me drive to see how I liked it. More than happy with the tune. Just wondered about the mpg.
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Randy

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Re: Lost MPG after custom tune
« Reply #3 on: November 22, 2015, 19:41:21 PM »

The ECM's can be programmed for performance, towing,  mileage and low/high octane. Talk to your programmer and let him know, they usually give a few re-tunes a year at no charge.

Something else could be wrong also, if you have allot of miles on the spark plugs and/or upstream O2 sensors a performance tune may not perform..


Good luck
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02 2500 Summit White-Loaded, Heated Leather Seats, Sunroof, Pioneer AVIC-Z3 Navigation System with back-up cam, front cam and Blue Tooth. Nelson Tune, UPD/K&N Intake, Dual Magnaflow SS Mufflers and 3" Tailpipes, Powermaster 225 Amp Alternator, Dual Optima Batteries, Full Traction 6" Lift with 305/70/17 Goodyear MT/R's and SSBrakes, Calipers and Rotors, E-Z Down Tail Gate.

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enoniam

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Re: Lost MPG after custom tune
« Reply #4 on: November 23, 2015, 07:54:25 AM »

Performance tune or not, you shouldn't be getting that much if any of a mileage hit unless he changed the part-throttle shift points a lot.  Does it upshift at around the same speed as before?
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25hundred

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Re: Lost MPG after custom tune
« Reply #5 on: November 24, 2015, 17:20:52 PM »

Where did you get the tune done? I am in Sherwood park is the reason I ask.  Those mpg numbers sound like big block stats!
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2005 / Black 2500. 496 Diablo Tuned, Air Raid intake, Magnaflow exhaust.

Lvrboy

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Re: Lost MPG after custom tune
« Reply #6 on: November 24, 2015, 21:22:09 PM »

Also in Edmonton and get about 400km to a tank of gas in the city. This is with a 6.2 however. Did you go to Moretto?
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mxzretta

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Re: Lost MPG after custom tune
« Reply #7 on: November 25, 2015, 19:27:44 PM »

New plugs and wires this summer as well as 02 sensors. Also a new transmission. Went to Coopers Custom Solutions. Just east of Beaumont. I'm getting about 550kms out of a tank with the 5.3
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Lvrboy

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Re: Lost MPG after custom tune
« Reply #8 on: November 25, 2015, 21:09:10 PM »

To me that doesn't sound that bad. Back when I had my 5.3 and 5.7 I was in those areas. Did you get a new converter put in with the tranny? Maybe a higher stall?
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2002 z71 powered by an LS3 480, 9000lb warn front winch, LED lights front and back, aftermarket ram air hood.. and more to come..bad assalanche

MS03 2500

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Re: Lost MPG after custom tune
« Reply #9 on: November 25, 2015, 22:26:14 PM »

It would be interesting to know what year and model he has. Along with what other mods he has done.  ???


Also why did he gut the cats
« Last Edit: November 25, 2015, 22:27:45 PM by MS03 2500 »
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2003 2500

mxzretta

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Re: Lost MPG after custom tune
« Reply #10 on: November 26, 2015, 05:42:26 AM »

Other mods are magnaflow exhaust, AFE cold air intake. Had the tranny replaced on holidays. It went in Merrit,BC. When it was in getting the work done they discovered one of the cats was plugged so I had them gut them instead of getting them replaced to keep the cost down. Old converter was installed. Btw don't do business with Murray GM very poor customer service. Took them 3 weeks.
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MS03 2500

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Re: Lost MPG after custom tune
« Reply #11 on: November 26, 2015, 07:55:24 AM »

I'll let the other folks address your tune, but since it's getting cold outside your mileage will be worst in winter.
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2003 2500

mxzretta

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Re: Lost MPG after custom tune
« Reply #12 on: November 27, 2015, 04:36:17 AM »

Forgot to add its a 2004 1500. And it has 220 000 kms
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25hundred

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Re: Lost MPG after custom tune
« Reply #13 on: November 28, 2015, 06:18:22 AM »

My mileage gets worse in the winter also, additives in the fuel and extra ideling.  Are you able to go back to stock with your programmer and see if the numbers come back up?  Or is the Ecu just flashed.
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2005 / Black 2500. 496 Diablo Tuned, Air Raid intake, Magnaflow exhaust.

mxzretta

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Re: Lost MPG after custom tune
« Reply #14 on: November 28, 2015, 06:35:53 AM »

I have had this truck for couple years and never got this bad of mileage. Even in winter I would get 500kms out of a tank. Out of my last tank I got 350kms out of 88 liters of gas. Think I will go back to my tuner and see what he can do.
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Henry

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Re: Lost MPG after custom tune
« Reply #15 on: July 24, 2016, 09:52:36 AM »

When I removed the cats I lost 2 mpg.
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