awilson40

I notice the same thing on my car, but not bad, jut not glass smooth like I would like. Try disconnecting your O2 sensor and see if it smooths out. The DME is looking at readings from the O2 sensor(mixture) and Flywheel sensor(for rpms) and is changing the mixture as a result of O2 readings, then signaling the Idle valve to keep the idle constant. This 'dance' goes on causing an unstable idle. You need to have a good clean O2 signal, Idle mix adjusted as near to perfect as possible and your idle speed set to near perfect. The closer you have everything set, the less the DME has to adjust and the smoother it will be. I may even wire in a throttle switch to take the car out of 'closed loop' at idle so it will just ignore the O2 signak and remove one variable. Most people just think I'm **** about tuning my car and dont even notice the uneveness. You cant even see it on a tach, but I can hear it.