Why does my idle fluctuate on cold starts?

Several different things can affect vehicle idle quality on cold starts. Emissions controls can cause problems -- such as restricted or inactive exhaust gas recirculation systems. Any number of components can contribute to the issues -- when the engine is cold, the processor is in "open loop" meaning the engine's processor is not really using vehicle data to try and optimize performance. It waits until the vehicle is warm to adjust air, fuel and spark mixture. In the end, hands on testing is needed to check all areas - fuel, ignition spark, air intake, emissions controls, not to mention engine compression and timing. www.repairpal.com/repair-shops