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Trying to tell if my new/used truck has been tuned by previous owner.


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Ok first I want to apologise if this thread has been done. I just started my account today. 

 

So I bought a 2016 Silverado 1500 LT Z71 4x4 with 37k miles a few days ago. It has a 5 or 6 in RC lift and 35x12.50r20 MasterCraft courser MXT tires on it. And the Hostile predator wheels. My question is, I don't know if the truck has been geared. Tuned. Or calibrated by the previous owner. The dealership doesn't know. The truck doesn't feel "sluggish" to me personally. I drive past the digital speed trap in my town and if I'm doing 30 on my guages the reader says 31-32... On the highway at 70mph my tach reads the notch under 2k.. so 1800?.. when cruising at 30-35 my tach reads around 1100-1200. I find I get in town with A LOT of stopping and going around 13mpg and that's driving very conscious. I notice it shifts around 2500 and then lower in the higher gears like 2000 then 1500.. but seems to chug along nicely around that 1200 mark. Also. My V4 mode has never turned on once. Not sure if that's due to the current cold northern Ohio climate right now. Or if the previous owner has a tune on it and disabled that feature. I just don't want to spend the money on a tune and calibration if I don't have to. When I floor it it gets up and goes fast imo. I don't floor it often at all. It doesn't pull or tow or haul much. I'm a maintenance engineer in a flat Ohio town of 50k ppl. So I don't think I'll regear because it won't be working too hard. If I could get some folks to shed some light on my curiosity I would greatly appreciate it. If all else fails. I'm buying a good tuner I guess...

Thanks guys. 

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Shifts from 1st to 2nd at around 2500 rpm? Sounds like the canned Diablo firm shift tune. Stock transmission tune on my truck shifted from 1st to 2nd at 12mph (~2k rpm), but the diablo TCM tune shifted at around 17 mph (~2500rpm). The other gears shifted a little later, but on the 1->2 was noticeably different. You can test this by driving very slowly with minimal pedal input. Record the absolute earliest speed that the truck shifts from 1->2. The custom tunes will calibrate shift points by speed rather than RPM

 

I'm assuming you have the 6 speed with a 5.3L?

Edited by Bill Reinhardt
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4 minutes ago, Bill Reinhardt said:

Shifts from 1st to 2nd at around 2500 rpm? Sounds like the canned Diablo firm shift tune. Stock transmission tune on my truck shifted from 1st to 2nd at 12mph (around 2k rpm), but the diablo TCM tune shifted at around 17 mph. The other gears shifted a little later, but on the 1->2 was noticeably different. You can test this by driving very slowly with minimal pedal input. Record the absolute earliest speed that the truck shifts from 1->2.

 

I'm assuming you have the 6 speed with a 5.3L?

Correct. 5.3 and 6sp. And yes the first gear slowly/normal acceleration is 2500 and the rest have a trickle effect of around 1200-1500 I'll try extra slow acceleration after work tonight and see what the speedo says when first gear goes in to 2nd. I found if I get up to speed around 30mph and then left off the gas pedal it shift to the comfy gear of what I'm thinking is 3rd or 4th. And it gets great mpg chugging along there. It almost feels like a smooth coasting. Kinda reminds me of a good size fishing boat if that makes sense lol. The accelerator still feels snappy too. Thanks 

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I would say the afm/dod is the biggest test. There are many shift tables and it isn't quite as simple as ball parking it. Also even if you did still do3ant answer anything. What tune do you have and how is it set. If it is a HPT tune the vin is registered with HP and that is great news as you just saved a lot of money and can roll into a good shop and have it looked and or retuned. Or order a used HPT as you don't need credits and pull info.

I always suprizes me how many tunes I see that something as simple as tire size is wrong. I see it on the cheap dash mount can tunes also. You but in tire numbers and it pallbark the size. It is ok but there are a few other tables that would like to know the real size. Also I Google the manufacturer's specs for the height and the do math for revolutions per mile. There are tire manufacturers well known for there tires running smaller then stated.

I would want to know for sure. Gas mileage sounds low I get 20mpg best and that is 24" and 550+hp turbo 5.3l 6speed. And that isn't driving like a saint....

Sent from my SM-N960U using Tapatalk

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35 minutes ago, 1SLOW1500 said:

I would say the afm/dod is the biggest test. There are many shift tables and it isn't quite as simple as ball parking it. Also even if you did still do3ant answer anything. What tune do you have and how is it set. If it is a HPT tune the vin is registered with HP and that is great news as you just saved a lot of money and can roll into a good shop and have it looked and or retuned. Or order a used HPT as you don't need credits and pull info.

I always suprizes me how many tunes I see that something as simple as tire size is wrong. I see it on the cheap dash mount can tunes also. You but in tire numbers and it pallbark the size. It is ok but there are a few other tables that would like to know the real size. Also I Google the manufacturer's specs for the height and the do math for revolutions per mile. There are tire manufacturers well known for there tires running smaller then stated.

I would want to know for sure. Gas mileage sounds low I get 20mpg best and that is 24" and 550+hp turbo 5.3l 6speed. And that isn't driving like a saint....

Sent from my SM-N960U using Tapatalk
 

Yeah the v4 has never engaged once and the engine has never shut off at a light or anything.. so that has most likely been disabled. And you're right There are several tuners out there so I don't know if it was HPT or black bear or Diablo etc etc.. plus I guess there's a chance he could have even put 4.10s in, but I am leaning towards he left stock gears and had a over the counter tune and calibrated the speedo.. I will cruise it around and run a couple tanks threw and see what average mpg is at also. I did just get it a few days ago and reset all the digital charts in the dash. Also like I said. There is A LOT of stop and go stop and go traffic and turning in my town. Also being cold doesn't help. All very short commutes so I think that's why my current average is 13.5 - 14mpg.. but again, I've only had the truck 4 days now. The speed trap says I'm going 1-2mph faster than my speedo in the truck.. which isn't that far off. I went past this trap 5 times... When doing 25 it says 25. Thanks again guys. Any new info is much appreciated.

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14 mpg is normal for short commutes in cold weather on average.

 

V4 may not engage unless certain conditions are met, such as engine/transmission fluid temperatures. I noticed you said you have a short commute, as do I. Before I got a tune, mine would not engage unless I drive it for a while and only when everything is up to operating temperatures... took 10-15 minutes of driving at least just to hit those temperatures. With a 7 mile commute, V4 never turned on for me, even on the highway. Have you tried a long highway run at normal operating temps? Light throttle at 60 mph for as long as possible?

 

Also, I'd still suggest finding out the minimum speed from 1->2 to rule out Diablo/Lew tuning:

I have an email from Lew stating that all the Diablew tunes do to increase shift points is to bump up the upshift points by 2 mph, the canned tunes bump it up by 4 or more. Stock 1->2 is at 12mph, Diablew 1->2 is at 14mph, canned is at around 16mph. Obviously there is more going on to change the shift quality and speed, however, the truck will REFUSE to shift any earlier than 14-16 mph if the TCM is tuned with a Diablo tuner, even downhill, no matter the temperature or circumstances. Your digital cluster should have a digital speedometer option to help identify the speed. 

 

If V4 refuses to come on at normal operating temperatures on the highway and your shift points are set by mph, its most likely a Diablo tune.

 

 

 

Edited by Bill Reinhardt
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The dealership is full of crap and can tell you if it has been tuned. I would bet it has been tuned because of the way you are describing the shifts, the speed, and the AFM. Now you mentioned re-gearing, well let's hope so, if not that just sucks, and if you tow that really sucks. A 6in lift on 35s and factory gears is just wrong and so much of the truck is lost. If there is one more thing you do to the truck let it be a re-gear if it has not been already and it you do 4.56 unless not ever or not much towing then 4.10 is ok.

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6 hours ago, Bill Reinhardt said:

14 mpg is normal for short commutes in cold weather on average.

 

V4 may not engage unless certain conditions are met, such as engine/transmission fluid temperatures. I noticed you said you have a short commute, as do I. Before I got a tune, mine would not engage unless I drive it for a while and only when everything is up to operating temperatures... took 10-15 minutes of driving at least just to hit those temperatures. With a 7 mile commute, V4 never turned on for me, even on the highway. Have you tried a long highway run at normal operating temps? Light throttle at 60 mph for as long as possible?

 

Also, I'd still suggest finding out the minimum speed from 1->2 to rule out Diablo/Lew tuning:

I have an email from Lew stating that all the Diablew tunes do to increase shift points is to bump up the upshift points by 2 mph, the canned tunes bump it up by 4 or more. Stock 1->2 is at 12mph, Diablew 1->2 is at 14mph, canned is at around 16mph. Obviously there is more going on to change the shift quality and speed, however, the truck will REFUSE to shift any earlier than 14-16 mph if the TCM is tuned with a Diablo tuner, even downhill, no matter the temperature or circumstances. Your digital cluster should have a digital speedometer option to help identify the speed. 

 

If V4 refuses to come on at normal operating temperatures on the highway and your shift points are set by mph, its most likely a Diablo tune.

 

 

 

Ok so further review of driving. The v4 mode still has yet to ever engage. And I have drove the truck all day. Also. You are correct, when I slowly accelerate first gear shifts to second at 12mph.. second gear is around 16mph. So maybe it's stock gear and stock tune and just has the v4 delete. Possible he had a tune on it and threw the stock tune back on when sold the truck. It was a leased truck. Then sold at auction. The dealership says the lift and wheels were on it when they got it and that was all they knew. I may just end up buying a tuner.. like a Dash tuner like Diablo. Really wish there was a way to tell if it's been re-geared. But at this point I'm thinking maybe it hasn't. Because at 70mph my RPM is 1700-1800(notch under 2k) and if it was geared in the 4.56 I think it would be more like 2100-2200. My mpg in town are super low tho 12.5-13.5, again it's 30degrees out and a lot of stop and go traffic. I just want a good stock tune that can land a little better mpg in city. I rarely drive highway and never tow or haul major weight. 

 

So final thoughts are the truck is on stock tune and stock gears with v4 delete. (Possibly previously tuned)

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Ok so further review of driving. The v4 mode still has yet to ever engage. And I have drove the truck all day. Also. You are correct, when I slowly accelerate first gear shifts to second at 12mph.. second gear is around 16mph. So maybe it's stock gear and stock tune and just has the v4 delete. Possible he had a tune on it and threw the stock tune back on when sold the truck. It was a leased truck. Then sold at auction. The dealership says the lift and wheels were on it when they got it and that was all they knew. I may just end up buying a tuner.. like a Dash tuner like Diablo. Really wish there was a way to tell if it's been re-geared. But at this point I'm thinking maybe it hasn't. Because at 70mph my RPM is 1700-1800(notch under 2k) and if it was geared in the 4.56 I think it would be more like 2100-2200. My mpg in town are super low tho 12.5-13.5, again it's 30degrees out and a lot of stop and go traffic. I just want a good stock tune that can land a little better mpg in city. I rarely drive highway and never tow or haul major weight. 
 
So final thoughts are the truck is on stock tune and stock gears with v4 delete. (Possibly previously tuned)
The problem you might run into if it's been tuned before is that dash tuners will recognize it has a tune on it already and it wont allow you to tune over it. It can say something like (non stock condition detected vehicle may have been programmed with competitive product). If that's the case you will have to tune it in a different way like HPTuners or Blackbear or something similar.
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2 minutes ago, Bash74 said:
32 minutes ago, ModernBoxChevy said:
Ok so further review of driving. The v4 mode still has yet to ever engage. And I have drove the truck all day. Also. You are correct, when I slowly accelerate first gear shifts to second at 12mph.. second gear is around 16mph. So maybe it's stock gear and stock tune and just has the v4 delete. Possible he had a tune on it and threw the stock tune back on when sold the truck. It was a leased truck. Then sold at auction. The dealership says the lift and wheels were on it when they got it and that was all they knew. I may just end up buying a tuner.. like a Dash tuner like Diablo. Really wish there was a way to tell if it's been re-geared. But at this point I'm thinking maybe it hasn't. Because at 70mph my RPM is 1700-1800(notch under 2k) and if it was geared in the 4.56 I think it would be more like 2100-2200. My mpg in town are super low tho 12.5-13.5, again it's 30degrees out and a lot of stop and go traffic. I just want a good stock tune that can land a little better mpg in city. I rarely drive highway and never tow or haul major weight. 
 
So final thoughts are the truck is on stock tune and stock gears with v4 delete. (Possibly previously tuned)

The problem you might run into if it's been tuned before is that dash tuners will recognize it has a tune on it already and it wont allow you to tune over it. It can say something like (non stock condition detected vehicle may have been programmed with competitive product). If that's the case you will have to tune it in a different way like HPTuners or Blackbear or something similar.

Oh dang. That's good to know for sure. Thanks. I'll look in to HPT and Black Bear. 

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Put the truck on a lift and in neutral. Spin one of your rear wheels 1 full revolution and count how many times your drive shaft turns (Mark it with a marker to help keep a reference point). This will give you a good estimate of what gears you have. If the driveshaft spins:
~3.5 times = 3.42
~3.75 times = 3.73
~4 times = 4.10
~4.5 times = 4.56

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3 minutes ago, 300 Blackout said:

Put the truck on a lift and in neutral. Spin one of your rear wheels 1 full revolution and count how many times your drive shaft turns (Mark it with a marker to help keep a reference point). This will give you a good estimate of what gears you have. If the driveshaft spins:
~3.5 times = 3.42
~3.75 times = 3.73
~4 times = 4.10
~4.5 times = 4.56

Oh nice. Thank you. I'll try that for sure before getting a tune! Deff wanna make sure I have the right gears punched in the tuner before flashing it. Thank you. I did notice there was already some marker lines on the drive shaft going from the drive shaft to where the u joint is. 2 different color lines. Like blue and dark red if I remember. Not sure if that means anything or if that's a factory marking from assembly or something. Or if he had the slip yoke worked on or new gearing or what. 

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If the speedo is wrong with oversized tires, that does not indicate to me that it’s been tuned, part of the tuning process is to get the speedo corrected. The lack of cylinder deactivation is a much stronger clue. One of the things the dealership uses to sniff out tunes is looking at how many times the OBD port menu has been accessed. Maybe they could look at that. But now you're getting into rough water... What type of warranty did the used truck come with? Are they making an allowance for having sold you a tuned truck? You certainly don’t want them to try and deny you a claim based on a tune that was installed before they sold it to you. You might consider calling BlackBear and Diablo -(Lew) with your VIN and explain that you’ve bought the truck and are trying to ascertain it’s pedigree.

 

Good luck and keep us informed. This is somewhat new territory.

Edited by Darksky
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