5.7 vortec mpg

[Mark Gilbert]

I'm not interested in a tune I find on a gas truck there a waste of money I've had gas trucks dyno tuned with exhaust and intake mods to just have $700 less in my wallet. I think my next thing will be mpfi upgrade and new fuel regulator looks like a pain in the A$$ of a job. However I do find unless my truck is plugged in when it's cold outside and it's its sits overnight it won't start it just cranks over but if it's plugged in it fires up the second you touch the key. I was told it could be the temp sensor by the thermostat so put new one in no difference also had a shop do a fuel pressure test and said it was very good well within spec for the 5.7 vortec. So only thing I'm thinking is the fuel injectors and regulator. Why like to get to the bottom of this as I'm confident this truck should be getting better mpg and have more power then it does. And when I did the plugs they were bad it ran lot better after tune up just didn't change mpg at all it did look like I had a couple cyclinders running a bit lean there was touch of white on three plugs. And the truck also has all new 02 sensors.

The problem with this statement is assuming all tuners are the same. There are countless stories of people taking their vehicle to get a dyno tune and then comparing the changes from their stock tune and seeing very little improved, or in some cases made worse. It is like every profession, there are good and bad tuners as well. I do my own tuning and while I have made improvements I would not call myself a tuner. Your best bet is to find someone that has a good reputation, I have yet to hear a negative experience about Black Bear, but I have never used them myself.

My only point is that you may be doing a disservice to yourself to write off tuning because of 1 incompetent tuner in a industry filled with them.

 

[L31MaxExpress]

My truck used to be the same way, wouldnt start under 35°F without the block heater plugged in. My spyder assembly was pretty clogged. I should've replaced them with MPFI unit, but at the time I didnt know there was a replacement. But now that I have a #7 injector not working right, MPFI will be coming soon.

And may i ask what vehicle you had dyno tuned? I've seen a few 5.7 vortecs around here gain 40-50HP just from a tune, no exhaust, intake, ect.

I gained about 40 ft/lbs of torque and over 30 hp tuning a 245 hp 5.7 Vortec calibration. With the 4L85E swap I used the stock 2002 0411 1-ton van tune. Then I removed torque management, tuned the spark and fuel, and setup the transmission to my liking. At the time the engine had a very small cam, 1.6 rockers and shorty headers.
Cam specs with 1.6 rockers
208/212 @ 0.050
.488/.488 lift
110 LSA
106 ICL

Before

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After

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Both the engine and trans ran cooler after tuning as well.

 

[CRF450R]

My truck used to be the same way, wouldnt start under 35°F without the block heater plugged in. My spyder assembly was pretty clogged. I should've replaced them with MPFI unit, but at the time I didnt know there was a replacement. But now that I have a #7 injector not working right, MPFI will be coming soon.

And may i ask what vehicle you had dyno tuned? I've seen a few 5.7 vortecs around here gain 40-50HP just from a tune, no exhaust, intake, ect.

It was a regular cab Short box Z71 GMC Sierra 5.3 was huge waste of time and money plus had to run premium and premium is hard to find as I live in middle of nowhere. I've road in other 5.7 vortecs all stock with way more power then mine my truck feels like a 6.2 gutless diesel. I guess I'll try the mpfi upgrade.

 

[Dre319]

With all the stop and go around here, I was lucky to get 11 mpg city.

Thats me majorly feathering the pedal too bro. Other then that I’m sure on a normal day with a slightly heavier foot, the MPG will diminish


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[L31MaxExpress]

Thats me majorly feathering the pedal too bro. Other then that I’m sure on a normal day with a slightly heavier foot, the MPG will diminish


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Traffic in front of me permitting my foot is always atleast 1/2 way down taking off. When the Express was stock the throttle was on the floor more often than not.

 

[Dre319]

I’ve had this truck since 2000. It now has a new motor from the dealership (crate motor) and it needed new injectors one day as well. The truck will average on a regular day, 13 in the city and that was both prior to the new motor and now. Fortunately now it’s not my daily driver so I never really worried about it anymore. Still if I could improve the MPG, that would be great.


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[letitsnow]

It was a regular cab Short box Z71 GMC Sierra 5.3 was huge waste of time and money plus had to run premium and premium is hard to find as I live in middle of nowhere. I've road in other 5.7 vortecs all stock with way more power then mine my truck feels like a 6.2 gutless diesel. I guess I'll try the mpfi upgrade.

I get the feeling that the stock LS motors benefit less than a vortec 350 from just a tune.

 

[CRF450R]

I get the feeling that the stock LS motors benefit less than a vortec 350 from just a tune.

I'm not doing a tune ive bin thinking of buying a HP tuner as my truck Is 98 and I could make money on the side working on freinds trucks. My truck is a 98 Z71 Silverado with 350 000km on it it was gutless truck from factory it's even more gutless now with age. All I would like to see is more mpg highway my engine finally came on the other day it to buddy's shop asap and it's coming up fuel pressure but when fuel gauge is hooked up fuel pump is still well in spec so we're set it's the spider injectors and or the fuel pressure regulator. Disconnected the battery for few hours no more engine light I'm sure it'll be back I ordered a mpfi AC Delci mpfi with regulator will be installing it over the Christmas holidays. Hope to gain some mpg and some power it's embarrassing trying the pass I drop it to the floor and it just falls on its face takes forever to pass anything I'm sure not a fan of these vortecs my 5.7 TBI was way better powerwise and mpg.5.7 vortec to 5.7 TBI swap

 

[letitsnow]

Hopefully the spider fixes it for you. When I go to pass, my vortec 350 pulls hard.

 

[L31MaxExpress]

Hopefully the spider fixes it for you. When I go to pass, my vortec 350 pulls hard.

x2
Always has....When it was stock more than once I ran it up to the 100 mph fuel shut-off without it ever even downshifting out of 4th.

This was mostly stock after a tuned 0411 swap.

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Not bad for a 3 ton brick on wheels.

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