Just as the title says, it surges, hesitates and bucks under light or medium throttle. WOT is fine. Its done this ever since I put the engine together, so I usually run it in open loop with the o2's disconnected. At idle the car smells filthy rich (even with the o2's plugged in). Well at work today I decided to hook up my scan tool and look at a few things with the o2's plugged in. Under part throttle, the long term fuel trim counts drop to 110-115 and it hesitates and bucks. Once i let the engine idle, it runs kinda bad untill the LT fuel rises to about 128 and then it idles fine. Is this some sort of a tune problem? I had it tuned from pcmforless. My o2 sensors are one year old, and they are bosch... maybe thats the problem. Anyone help me out?

 

I have heard from lots of people to only use AC Delco O2's because the aftermarket ones can have all sorts of problems. They are like $35-40 each on Ebay. Well worth the little extra to have the piece of mind.

 

I just got a tune from them too, and imm experiencing the same type of problems. When I accelerate anything less than wot, instead of the power being a smooth linear increase, it kinda surges. Im working w/ him now to fix it. I hope we can.

 

make sure you guys check your spark plugs... i had this same problem when i had new plugs and wires installed by a **** poor shop (Burkart Automotive, yes the same burkarts that run the funny car) and they installed my #6 and #8 cylinder spark plugs with absolutly no gap... car bucked like mad when i was just trying to cruise but pulled fine at WOT