No power uphill

[GMC Canteen]

I have a early build 2015 gmc 3500 dually , w 66k i got in 2014. Have had this problem for awhile now. No power under load, if you slowly press gas it’s ok but no power under load, just bogs and won’t go over 2k rpm,Replaced fuel pump, air filter, catalytic converter , maf sensor. Don’t know if it related but also replaced a/c compressor and condenser but ac still blows at half speed and if you turn temp dial off of cold it gets hot and stays hot no matter what you do with dial.no cels or codes Please help

[GMC Canteen]

I have searched and gotten several answers, do you think I should try replacing the plugs ? Also someone said something about a “spider”? There are no wires right ? Just coils and a bad coil usually throw a cel , I am still under warranty and dealer has done all past work but he ran all the diagnostics and comes up empty, I could barely drive home today, much worse at end of day when hotter.

i use this truck for my livelihood, please help ! 

[GMC Canteen]

Come on guys , no ideas ? I have seen this problem many times around web but no real answers.....

[swathdiver]

I'm not familiar with K2 but there should be internal BCM codes with regards to the AC.  Now, is the engine a Duramax diesel or L96 gas?  

 

What happens if you gun it from a stop?

[GMC Canteen]

Sorry guys , I have the gas 6.0, if I gun from stop it will hesitate then take off and if I gun it while driving it will slowly add rpm, but if I feather the gas I can drive fine, almost 

[swathdiver]

Sounds like you're driving around with a locked up torque converter.  Or a bad MAF sensor.  If it was clogged cats it should have thrown a code.  Have you checked your Long Term Fuel Trims?

 

It's almost impossible to properly diagnose these trucks without a bi-directional scan tool.  The Tech2 is too old for these but you can get the MDI  with GDS software and put it on a laptop and see and check and test everything necessary to find the problem.

[GMC Canteen]

Dealership has used diagnostic tools and replaced maf sensor, I think it may be torque converter as I am feeling excess heat right under driver door

[MNorby]

Definitely let up know what you find. 

[GMC Canteen]

Dropping off at the dealership today and hopefully I’ll get an answer 

[GMC Canteen]

Heard from dealer today, my second cat was clogged, they had to replace the ECM because it was not throwing codes that their scan tool picked up and whole A/c control panel, have to pick it up Tuesday  , thank goodness I bought extended warranty 

[avalonandl]

The second cat is not monitored on the 6.0- so a new ecm is not the issue. 

 

But your symptons are exactly those of a plugged cat. Did they say what causes a plugged cat? Misfire?

[redwngr]

Have the easy things been checked?

 

Does the truck have adjustable pedals?

Are they all the way ahead?

 

Does it have floor mats that prevent pushing the pedal all the way down?

 

[4wdriver]

On 9/10/2018 at 12:47 PM, avalonandl said:

The second cat is not monitored on the 6.0- so a new ecm is not the issue. 

 

But your symptons are exactly those of a plugged cat. Did they say what causes a plugged cat? Misfire?

Does not monitored mean that if it were missing the truck would be unaware?