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

[swathdiver]

So no V4 while coasting to a light or downhill off a bridge?  If not, it's been turned off.  

 

Get a Carfax and see if it shows where the vehicle was previously serviced.  Then call the dealerships and kindly ask them for any maintenance records.  If you show proof of ownership they will usually give them to you.  Somewhere along the way you'll identify the previous owner and can ask him/her directly.  Might even be a member of this forum.  If the truck has navigation, check for saved addresses and such.  

[1SLOW1500]

7 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.

 

 

 

Oh I hope there is a little more to it that just a few mph increase in shift points. That can cause real issues. That Diablo tune sounds limiting. I would like to read a tune of a diablo tune. and see what was going on. Maybe I should offer a local member a free unlock and HPT tune to get a copy. 

[ModernBoxChevy]

4 minutes ago, Darksky said:

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.

Right. Well the speedo seems to only be off by 1 or 2 mph.. if it wasn't calibrated wouldn't it be off more like 3-4mph? At the 30-35mph range. Also the power train warranty I'd what I still have left as for warranty. Has about 2 years left on it and I asked if that is effected being it has a lift and wheels. He said "no. It's got a note attached to it that the vehicle is a modified vehicle from us" 

[ModernBoxChevy]

6 minutes ago, swathdiver said:

So no V4 while coasting to a light or downhill off a bridge?  If not, it's been turned off.  

 

Get a Carfax and see if it shows where the vehicle was previously serviced.  Then call the dealerships and kindly ask them for any maintenance records.  If you show proof of ownership they will usually give them to you.  Somewhere along the way you'll identify the previous owner and can ask him/her directly.  Might even be a member of this forum.  If the truck has navigation, check for saved addresses and such.  

Correct. No v4 when coasting. On highway. Or at idle. I do have the Carfax on the vehicle. Shows as a leased vehicle from Michigan. Then sold at auction in Columbus Ohio area. I'll check the contacts in the trucks entertainment screen. Be cool if I can just get the previous owners contact from there. I know in past vehicles I've found old contacts. 

[swathdiver]

3 hours ago, ModernBoxChevy said:

Correct. No v4 when coasting. On highway. Or at idle. I do have the Carfax on the vehicle. Shows as a leased vehicle from Michigan. Then sold at auction in Columbus Ohio area. I'll check the contacts in the trucks entertainment screen. Be cool if I can just get the previous owners contact from there. I know in past vehicles I've found old contacts. 

That suggestion is what I did with mine and was able to get service records at the two dealerships that worked on it.  Even have the mechanic's name.  Wasn't able to reach the owner, he passed away.  Google even showed the truck in his driveway.

[Bill Reinhardt]

17 hours ago, 1SLOW1500 said:

Oh I hope there is a little more to it that just a few mph increase in shift points. That can cause real issues. That Diablo tune sounds limiting. I would like to read a tune of a diablo tune. and see what was going on. Maybe I should offer a local member a free unlock and HPT tune to get a copy. 

You are correct, much more goes on than just that!

 

However, we are trying to figure out if the OP's truck is tuned and if so, by what. 

 

The Diablo tunes do this, it's a measurable trait that the OP can go and test to rule out a Diablo tune. These are also relatively cheap tunes, so I'm not surprised. Email from Diablew attached below.

 

I don't think OP bought a truck tuned with a Diablo tune because not only would the transmission have a particular and unique shift behavior, but also the speedometer does not seem to be calibrated for the tires (which is just as easy to adjust as disabling V4 with the Diablo. The options are right next to each other).

 

It's entirely possible that the previous owner bought a used Diablo, disabled V4, then sold the unit or did not do anything else with it. Unlikely as there are far simpler and cheaper methods to only disable this one feature and not apply a tune.

 

Edited December 24, 2018 by Bill Reinhardt

[300 Blackout]

You need to measure the actual diameter of your tires to make this calculation more accurate, but if you follow me here you’ll get an idea of what gears you have.

 

Data for calculation based on info you’ve provided:

Tire Circumference = 109.95”

Tire revolutions/mile = 576.26

Engine RPM @ 70mph = 1800

6L80 6th gear ratio = 0.67

Driveshaft RPM @ 70mph = 2686.56

 

576.26 revolutions/mile x 70mph = 40,338.2 revolutions/hour

40,338.2 / 60 minutes per hour = 672.30 revolutions per minute

 

2,686.56 driveshaft RPM / 672.30 wheel RPM = 3.996 gear ratio.

 

If your tires measure bigger than 35”, then you have 4.10 gears. If your tires measure less than 35” then you have 3.73.

 

If your truck isn’t tuned, your speed error will be just under 10%. If your speedometer reads 70mph, your actual speed will be 76.8mph. If you have a second way to verify your speed with cruise control set at 70mph (iPhone gps works) then you can see if your truck speedometer is corrected.

 

[Scooby1974]

On 12/22/2018 at 5:30 PM, ModernBoxChevy said:

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. 

Hi there, sorry for the late response. It sounds like you definitely have some kind of tune/programmer. Your truck should be shifting like a glove. The previous owner did some work on it and for sure a tune was added to compensate for larger tires/wheels.What size wheels/tires does the truck say it came from factory?

The shift points are too aggressive to be stock. I don't think that the gears were replaced because its cheaper to just add a tune to get the speedometer about right and the extra hp to move the truck. As I see the Dealership where you bought it knew the truck was not stock and all they had to do is replace the computer but then again if you bring the truck in for any reason, thats when the Dealer is going to tell you that your warranty is not good due to powertrain modifications.

I would have test drove it first and see where the limiter would stop or just by feeling the shift points.

The tune is probably locked. Get it tuned back to stock if possible if not replace the computer.

By the way I used to own a 2016 Silverado Regular cab and the 4 cylinder light would only come on if I took off barely touching the gas pedal or coming to a stop.

Hope all is well for you and your truck.

 

[Evan Poulos]

I’m a tad late to the party, but I’m having the same issue as OP. I recently purchased a 2015 Silverado LT Extended Cab that the previous owner modded. It has MSD coils, upgraded spark, a Jammer CAI, and I have no idea what else. It shifts and sounds aggressive, however my 1st-2nd shift happens around 25-30mph. Trying to find out how to reverse search what was done to the truck somehow

[pokismoki]

if you purchase HPtuner software , you can install the OEM tune and adjust that to your liking,. you can also do a comparo file look at OEM vs your tune see whats wacky or cool