Hi all I am new to all this performance stuff and need some help. After reading your posts I sounds like you guys know how to tune modified engines so I would like to ask you for assistance.
I have a 2000 GMC Yukon SLT 5.3 4WD.
I recently replaced my stock 5.3 engine with a LS 327/327 engine. http://www.chevrolet.com/performance...nes/ls327.html
I added a hughes 22-20L torque converter, and blocked of the EGR valve.
The Truck runs better, more power and shifts OK. But is rough and misfires at idle and looses power on the highway.
I replaced all spark plugs and leads, no improvement, no codes found when scanned.
It runs rich, fuel consumption is high.
It has only been driven from 1600 miles.
I think it has major tuning issues, but I am a complete newbie to this whole car tuning thing.
If there is someone on the forum who understands what may be wrong and how I could go about fixing it, I'll greatly appreciate their help.
Does it need a HP tune or not, might there be something else wrong?
Chevy327