2003 Silverado SS (6.0L)

About 6 weeks ago truck started having a weird delay between the 1-2 shift. Its almost the exact same amount of delay every time, not matter if I give it more gas or just sit right at the normal shift point. It also isn't as responsive and feels like a bit of a turd. Below is a quick vid of the delayed shift.

Silverado SS hesitation shifting from 1-2. Transmission or computer related? - YouTube

About the same amount of time my speakers started popping and my battery draining dead overnight. I traced that problem to the radio fuse which had a large parasitic draw when the truck was off. I don't know if the two are connected at all, or just coincidental.

On a side note when I first got the truck it wasn't shifting at WOT unless the gas was let off. I took it to a performance shop and they said the PCM tune was wacky. Got it tuned and it had ran great up to this point. Is it possible for the tune to "go bad" or corrupt? Could it be an electrical issue that relates to the radio not shutting off?

I do throw some codes every now and then. Usually it's a P0171/P0173 or 2/4 combo. Sometimes it throws a P0101 with those as well. When it does throw the codes its always around right after the delayed 1-2 shift.

What I've done so far (and plan on doing):

-Cleaned then replaced MAF & connector

-Replaced TPS & connector

-Replaced O2 sensors.

-Replacing MAP tomorrow.

Plugs & injectors are all newish.

The truck has been throwing the lean codes since I got it, but I've never had any issues with the tranny shifting strange or the P0101 codes.

I know these trucks had weak transmissions, but it just doesn't seem like the transmission is going bad to me. Its not slipping, I'm not missing an gears, and it shifts from D-N-R-N-D quickly and smoothly. Could it be a big vacuum leak? I'm probably going to have to end up taking it in for a fog test and maybe get hooked up to a real scanner. Just wanted to see if anyone on here had any other ideas.

Thanks ahead of time.

 

Check tranny fluid?

 

It seemed fine to me.

 

Have try changing any solenoids in tranny

 

MAF is one of main inputs to TCM for shifting. If it delays it could be because of DTC. When p0101 sets it'll freeze trans adapts and command full line pressure. With the p0171 and p0174 lean codes I'd check for leaking intake manifold gaskets. Very problematic. I'd replace intake manifold gaskets before replacing MAP sensor or any other sensors. Also make sure there are no intake leaks post MAF sensor. Unmetered air getting into engine will cause all those DTC's to set

 

My 04 Yukon denali started doing the same thing. No codes though. Thought it was tranny related didn't even think of intake gasket

 

Thanks for the suggestions guys. I'll be taking it in this coming week to see what's up.

In the meantime, any idea what this unplugged connector goes to? Its the blue one hanging down in the middle of the below picture. It is in/from the same bundle that the MAF wires go to.

 

I'm not exactly sure. But it doesn't plug in to anything. A lot of vehicles have this. I think it's one of those items GM decided to save money on and instead of making different harnesses for every vehicle they just decided to leave a connector and plugged and program the vehicle per the RPO's it is equipped with. I always see this connector and think myself where does it go. My best guess is for vehicles with rear A/C but don't honestly know.

 

x1 on checking for intake leaks. best to check when engine is cold. will usally leak more when cold. old style intake gaskets used on pre 04 models leak all the time the rubber is orange on them and new ones are green. i do not like the felpro metal ones except on boosted applications.
i would check
check fuel pressure for intermitant lean codes. also open the relief valve fully on the fuel gauge to test the volume of the fuel pump. engine should not miss a beat or stuble when the valve is open. also a purge valve that is stuck open can cause p0101 and lean codes when the fuel tank level is low. easiest way to check purge valve is to unplug it pull the evap line off of it run the engine and check for vaccum coming through the port.

 

the phantom connector is for a low coolant sensor which the gas motors do not have. the connector is the same for the low pressure cycle switch is the same but when one is hooked up wrong the a/c no worky and it sucks to try to diag