Bowtyrel

Just finished my th400 swap and the car wouldn't idle at all, kept surging until I hooked up the speedo but once I shut the car off it's like it resets itself and starts surging again until I move the car and the speedo starts working. Can this be fixed with the retune or is there another problem? mph is not accurate and needs to be adjusted also.

JetMech442

iTrader: (1)

I'll take a crack at this one. First, tell us what engine/mods/ecm etc.. are.

I'll make an assumption that you have an LS1 with an LS1b ecm. You have a throttle cracker table for both P/N and in Gear. Is your ECM recieving a signal that your trans is in PN or inGear to tell it what table to use? I propose that when you start moving, the cacker table adds airflow and settles your idle. but when you stop that added airflow decays out and surging starts again.

So to keep it short, yes I think a retune would help this situation.

Bowtyrel

Sry yes ls1 h/c/I and it was a 6 speed before, neutral safety switch wired up and that's it