2000 Yukon slt 5.3l

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Rollincoal

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Hello to all. Wondering if anyone can steer me in the right direction. I have a 2000 GMC Yukon slt 4wd with 5.3. Cats were plugged so I deleted them when I did my long tube install. Also did cai, and egr delete. I have 1 7/8 speed engineering LT’s going to 3 in x pipe with a foot or so of straight pipe Out of the x to dual flowmaster outlaw mufflers with turn downs dumped out before the rear axle. Truck starts and idles great. Something is definitely wrong though. I don’t know if all the tables are out of sorts, or maybe not enough back pressure? Runs up to 40-45 mph great then it hit a wall. It’s like it wants no gas or all the gas but no inbetween if that makes sense. Definitely smells like it’s running pretty rich. Maybe need longer exhaust and tuning? Anyone want to chime in. Please and thanks!
 

Teamiez

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What did you do with the egr sensor & the o2 sensors
 
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Rollincoal

Rollincoal

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Truck also wants to seem to almost stall while in reverse, almost like an aggressive cam would act.
 
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Rollincoal

Rollincoal

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Maybe just need to keep driving like it is until I do my cam swap and intake manifold/TB then go for tune and see what happens. Almost just seems like a back pressure isssue
 

Teamiez

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Maybe just need to keep driving like it is until I do my cam swap and intake manifold/TB then go for tune and see what happens. Almost just seems like a back pressure isssue
I’m not a expert but I think vehicles do need some back pressure to run properly, not to sure.
 

Joseph Garcia

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Do you have a Tech 2 or equivalent bi-directional scanner? I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me will chime in.
 
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Rollincoal

Rollincoal

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Hey thanks for the reply Joseph, unfortunately I don’t have a scanner. I have had ses light on for months due to the egr delete, and rear o2s are not in due to lt header install. I’m kinda scared how many codes it might find. The truck sounds so good I hate to mess with the new exhaust. I think it’s lack of back pressure
 
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Rollincoal

Rollincoal

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Need to find someone in North Carolina that’s near Greensboro! That can tune ls engines.
 
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Rollincoal

Rollincoal

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Teamiez you’re absolutely right, I seriously think it’s combination of not enough back pressure, and the factory tables for everything are just out of whack from all the mods
 
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