The 1/2 shift has been shuddering and slipping (F-ing new 80e swap UNREAL, but that's another story) and it seems the slipping is going into the other gears, just ever so slight.

Well the other day I nailed it to pass a car and it was like going nowhere real fast, stuck at the 5100RPM and pinging like a coffee can with nuts and bolts in it. This an isolated instance. Until yesterday, now it's permanent. I cannot accelerate without getting lots of resistance under load. The boost gauge shows excessive boost (like I am putting it under tons of load ie;6-7psi at 3K RPM and only 25%TPS), it doesn't feel like it is slipping, feels more like fuel is just not getting there. No codes, no misfires, no broken spark plugs, the injectors are firing at idle, I don't know how to test them while driving besides HPT telling me bank one is 20ms and bank 2 is 20ms. So that seems fine. It can't be mechanical can it? I mean it idles and drives fine unless you give it about 25%TPS or more. Also if you on the highway or whereever for that matter and try to floor it(I don't try anymore) the boost gauge will go to 10.3psi. Since my swap and install of the 6.0/4l80 it has never went over 7.6psi at WOT.

Anybody ever heard of this...could the trans be causing so much parasitic loss it's like holding the brake son the power train? I mean if it was just slipping then I'd rev until the limiter hit. I don't get this one.

Help?

 

From what I've read on this site and LS1Tech the 6.0L flows so much better than the 4.8 or 5.3 that you lose boost. Most guys seem to swap to a smaller pulley when they put the 6.0L in. As far as the 4l80E acting up, I'm not sure. Almost sounds like your converter is not seated or locking up right. Maybe Zippy will chime in, he's the tranny guru. I hate transmissions, they are the devil.

 

Sounds like the cat collapsed to me.
My Z28 did the exact same thing. Check your cats.

 

That's one of my suspicions, driving home yesterday, I thought about the cat taking a crap and clogging **** up. I did open my cutout(after cat) and it seems to have a little more "get up" but then it went away(the get up). However, I am sorta sold on the trans really screwing things up. I won't know until I get it out Monday and tear it apart, it's definitely screwed in the 1/2 area. It's still under warranty (what you call a warranty ). I just don't understand the **** loads of boost all of sudden with no power. If the trans was restricting, or the cats for that matter wouldn't the boost still be like always....7.6....not freaking 10.x?

I will check my cats though.

 

your boost will be higher with clogged cats, the blowers pushing the same volume but the cats are not letting it flow threw, as the back pressure increases so will the boost pressure

 

Yes the boost will be higher... much higher. I had the EXACT same suspicions when my cats went. If you can, I would go without them. I doubt that any cats will last long on your truck.

 

I live in MD, just as well be California as far as emissions goes. Thats the only reason. And you're right, this is my second set. But the others "melted" away. (very rich scenario). I understand the higher boost to lower flow, but I would never would of imagined the "banana in the tailpipe" effect.

 

Mine was doing this exact same **** tonight. No idea why,but, I can guarantee it's not the cats on mine anyway. They are brand new dynatechs. i don't know what the hell it is. my truck is like new england weather. If you don't like it, give it a minute, it will change. lol

 

You know dewmanshu, you truck sound so very much like mine it isn't even funny. I have the same thing with out the noise. the truck makes a hole lot of noise and boost but isn't very fast. I will be removing my cats this week I hope.

 

I see you have that wideband, notice any lean or excessively rich scenario's when you nail it with this problem?

My cat's are fairly new, I know in the world of mod's you can't rule anything out cuz it's new, tell my first set of "dynatech" cats that I lost due to running way too rich. I got the biggest cats this time around, still dynatechs. They only have about 6K on them. But Greentahoe is right, our setup wouldn't let them last anyway. Ugh. Let me know DenaliHD and Wilde how your's turns out.