My BlackBear post

[PNWMuseumman]

Sub'd for the updates, trying to sell my wife on BB tuning her Denali.

 

[M1Gunner]

Fuel trims and engine speed will be a dead give away for a vacuum leak. Especially going from idle to accelerate to higher steady speed and back to idle. Hopefully that’s all that’s needed was that 90.

 

[cmc76]

I will find out as soon as i get it put back on. The only other thing i found, i believe its a purge solonoid. Its looser than it should be, but the nut that is affixed to the manifold is stripped. Im going to have to figure out how to get it out and jb weld the nut back in so its secure. Im not sure what if any effect that is having.

 

[Rocket Man]

Justin has helped me a few times with problems, some not even tune related. One of the reasons I love the Autocal. Tunes usually take a week or more, be patient.

 

[cmc76]

So I got the vacuum break fixed this morning. I ended up having to put some random fittings together myself. After a few days of looking, i couldnt find the OEM elbow. But i made it work.
Are these trucks vacuum assist on brakes? I had noticed some weak spongyness as of late, figured i would pull a wheel off once it is finally warmer. But placebo or not, after the vacuum fix they seem to perform better.
So i did a new log of the existing tune. Got an error code again. Pulled the radio fuse and then it did a correct read. The last file of the existing log i sent was corrupted and not able to be used. My only concern is that todays log didnt save with the correct date.
I did another log file driving. Justin had asked for a new one once vacuum was corrected, and some higher rpm pulls. Assuming the vacuum is now set. I went out for a half hour of harder driving. I put it in my email to Justin, but I am sure someone will chime in here. In D, i couldnt seem to get it to 5000 rpm. JUst didnt want to go. I pulled constant up to the govenor. Since he asked for 5k though, i i dropped into 3 and launched and it was no problem. Again, since i never in the past really pushed it, I am not sure if that is normal or not?
So thats it for today. Assuming the files are all readable, I should have some news next week.

 

[Rocket Man]

So I got the vacuum break fixed this morning. I ended up having to put some random fittings together myself. After a few days of looking, i couldnt find the OEM elbow. But i made it work.
Are these trucks vacuum assist on brakes? I had noticed some weak spongyness as of late, figured i would pull a wheel off once it is finally warmer. But placebo or not, after the vacuum fix they seem to perform better.
So i did a new log of the existing tune. Got an error code again. Pulled the radio fuse and then it did a correct read. The last file of the existing log i sent was corrupted and not able to be used. My only concern is that todays log didnt save with the correct date.
I did another log file driving. Justin had asked for a new one once vacuum was corrected, and some higher rpm pulls. Assuming the vacuum is now set. I went out for a half hour of harder driving. I put it in my email to Justin, but I am sure someone will chime in here. In D, i couldnt seem to get it to 5000 rpm. JUst didnt want to go. I pulled constant up to the govenor. Since he asked for 5k though, i i dropped into 3 and launched and it was no problem. Again, since i never in the past really pushed it, I am not sure if that is normal or not?
So thats it for today. Assuming the files are all readable, I should have some news next week.

Yes the brakes are vacuum assist unless you have the hydroboost option which is unlikely. Hydroboost brakes are assisted by the power steering pump so they're hydraulic but it's not a common option. And not being able to rev to 5000 rpn in D on a stock tune is normal. You'll be able to once you get your tune though. Looking forward to your impression after the tune.

 

[swathdiver]

If you've got a round booster behind the master cyllinder and a hose coming off of it to your intake, that's vacuum assist brakes. If no booster and a bunch of metal hydraulic lines running down to the power steering pump, hydroboost. Mark just beat me to it but I'm not gonna erase my post! LOL

 

[cmc76]

Dont worry about erasing. Id rather have more information than less.
And Im anxious to see as well. This isnt my first modded truck. But the first Tahoe I have had. This stuff is quickly addicting.

 

[cmc76]

Another update.
So I still have a vacuum leak. Once temp breaks ill investigate further.
And Justin said I was only at 79% full throttle. I just might be the dumbass who lets the floor mat get stuck under the pedal....stay tuned

 

[cmc76]

So other than this loose purge solenoid. I cant find any leaks. I finally got it out .The tiny brass insert had spun in the manifold. I'm going to try to epoxy it back in. The solonoid wasn't snug .Could have been losing pressure.
And i pulledmy floor mat out. Sure as shit was blocking pedal travel. Wtf?