I have a 2008 GMC Sierra 5.3l. I just installed pacesetter lts and had nelson performance do a custom tune and its throwing codes for rear o2's and front o2's up. I called Nelson performance and they are telling me that it's only the front and that the o2's are having trouble heating up. I called tsp and they told me the codes are front and rear. what can i do to fix the front codes and will my truck not perform like it should with the front o2's not heating up?

 

TSP won't know if it's both without looking at your tune. Nelson more than likely shut the rear 02's off if he knew you were adding long tubes.
I don't know if it causes any fueling issues when the fronts don't warm all the way up but you can swap them out for some out of a corvette IIRC.

Someone will come in and confirm or correct that as I'm not sure which ones to replace with

What codes did it throw?

 

What are the codes?
With longtubes having the sensors much further down stream,this can cause the sensor 1 heater performance codes

 

i had the same problem i just swapped out the fronts with come corvette o2s the part number is 91111 i think im not sure but it that fixed my problem

 

To really help you with correct advice, we need you to post up the DTC's.

 

got it fixed. thanks for all the help and response. Nelson is removing the heater performance codes on the front.

 

Here's another question is it normal to spell a very strong fuel odor from the exaust(tail pipes)?

 

smell

 

yup. until you get a tune, you'll probably be running pretty rich

 

It has a tune, but is getting another done and we be installed next week. Will a good cam really open the motor up and if so what's the best cam (DD) to go with? Want some serious hp with out spending 6k on a supercharger.