[SoCal LS-L]

Originally Posted by dcarrb

I understand that the intake of an SVX can get pretty gunky and suppose that might impede performance ever-so-slightly, but I need someone to explain why this would cause a stumble or miss.

dcb

My first thought would be the Idle Air control, the actuator that opens and closes to allow idle while the butterfly valve is closed. Gunk causes the actuator to not open or close properly, which will screw with idling. This same gunk will also coat intake and exhaust valves, causing them to not seat right, leading to compression leakage from the cylinder, which makes the engine idle rough due to misfire. Even slight misfiring screws with fuel trim, which will also make the car idle/run weird and substantially degrade performance.

I invite you to pull the small EGR temp sensor off and see whats in there. Even the big plastic intake tube gets really nasty as much of the PCV vapors are pulled directly into it (all those hoses attached suck in crankcase fumes and cylinder blow-by)..... which then coat our butterfly valves and the rest of the intake runners and attached components.

Many here have used the Seafoam with very positive results, it takes time to do it right but from what I have read the benefits are worth the effort.