Diablosport Forums

I just bought an inTune and was very excited to start tuning my truck. I've used a few different tuners on other cars, so I have a fairly good background. I updated the device on my desktop computer and went out to my truck to get the tune started. The only two tunes available were the DiabloSport tune and the 87 octane tune. Since I had a full tank of 87 octane fuel, no real engine modifications, and no plans for major mods, I figured I would install and stick with the 87 octane tune.

It wrote to the PCM with no issues. But as soon as I started the truck for the first time, I noticed the idle was jumping around slightly, but I figured that the fuel trims may have been reset and just need to relearn. No biggie. I took the truck for a test drive. The tune made a major difference. The shifts were held longer and were much firmer. Much more than I wanted, or would even expect. Because I don't want to break hard parts on my truck while towing with such hard shifts, I tried to dial these down by adjusting the shift time and shift pressure back in the 87 octane tune. None of the changes I did made a difference.

I had a small trip over the weekend, so I figured I would just drive it gently and see if the shifts softened up over time as things settled in. The first portion of my trip was small time city. So I noticed the increased power, and of course the break neck shifts. Once on the highway with the cruise set at 65mph, I noticed the transmission temp gauge was much higher than I have ever seen it before. It was almost up to 200 deg in 50 deg ambient temps. And the engine temps were higher than normal too. Over 200 deg as well. Then I noticed that the RPMs were higher than normal and the average MPG was decreasing on the onboard calculator. I was down to almost 8.5 mpg with no trailer and steadily decreasing on open flat highway. Then I put it all together. It didn't seem like the torque converter was locked up in 4th gear. I didn't notice if it locked in 3rd or not. But it definitely wasn't locked in when on flat roads on at 65 mpg. My usual RPMs are around 2000 when at 65mph. With the 87 octane tune, I was running 2400-2500rpms, the tranny was building up heat, the engine was hotter than normal, and the fuel mileage was horrendous.

So I pulled off an exit, reset my tune to stock, and hopped back on the highway. The change was instantly noticeable. The RPMs were back to normal at 2000. The tranny temp started to cool off and settled in around 150 degs. The engine coolant temp dropped back below 200. And the fuel mileage started to slowly increase back to expected.

So my question after all of that, is this normal? Should the torque converter be locked up with the 87 octane tune? I wasn't expecting miracles, but I thought I would gain a little seat of the pants HP and torque increase, and a slight increase in mileage. I wasn't expecting it to drop under easy, normal driving! And the shifts! Is there any way to soften them up just a little? Nothing I did seems to work.

Any help you can offer is greatly appreciated.

Is this a 6.0 or 8.1?

I'm sorry, I should have included that information.

The Avalanche 2500s all have the 8.1L engine and 4L85E transmission.

post the tune files from the tunes folder please.

These are the two files in the tunes folder.

Can anyone offer any advice on why this tune acted the way it did on my truck? Or what can I do to use the inTune with my vehicle?

Thanks.

Can you tell me which Tune you loaded here?

Zach wrote:Can you tell me which Tune you loaded here?

I loaded the 87 octane tune.

Can anyone provide any insight? I would love to use my tuner, but it has been sitting on the shelf since this happened.

Did I do something wrong?

Is this the wrong place to ask these kind of questions?

Any help you can provide is greatly appreciated.

Thanks!

Please load this up and let me know how it reacts.

I have the same exact problem. With the factory settings my torque converter would lock up at 55 mph with light throttle and letting off the throttle slightly , and about 60 mph with steady throttle. Loaded the 87 economy tune and now the converter doesn't lock up until 70 mph with light throttle and letting off the throttle slightly , and about 75 to 80 mph with steady throttle and then will unlock again if below 65 mph where as the factory tune it wouldn't unlock again until below 50 mph with light throttle. I have a predator 2. 2003 chevy avalanche 2500 with 8.1 and with 37" tires and 2200 rpm stall speed torque converter. I tried messing around with the 1 to 2 , 2 to 3 , and 3 to 4 shift pressures and made no difference.

Never mind on that last post. My speedometer was off and was reading low so when i corrected it it reads higher and is dead on. When my converter locks in at 65 to 70 mph im at 1500 rpms which seems about normal as my speedo was off by about 8 miles an hour before thats why it locked in at a lower speed before , was really doing 65 and thought iwas doing around 55. So all is good and working good.