JohnandMindi

New to this forum... Having an issue with my 99 Camaro with a V6 3800 series. The car runs rough at cold start and will almost stall out if it is put in gear before it smooths out. Once it heats up for 30 sec-1 min or so it runs fine most of the time. I am having a studdering problem occassionally when accelerating from stop and the car will sometime studder between 40-50 mph. This occasional studder appears happens at both low 500-700 and higher RPM(2000-2500). Every so often it throws the check engine light with P0300(autozone read this for free) but the light shuts off within 20-30 miles of additional driving. I have no mods on this vehicle. I have replaced the Spark plugs and wires with Bosch parts, replaced the fuel filter, PCV, and had the fuel system cleaned with my recent oil change. None of this seems to have helped the situation. Not sure where or how to proceed from here. Any help would be greatly appreciated.

maxharvard

If you've replaced the plugs and wires, the only thing really left is the coils and the injectors. Fuel system cleans are pretty much worthless, ask the Car Talk guys... even they think its junk (not the fogger style, sometimes that helps), but the traditional run some shady crap through the fuel system type stuff.

It would be nice to know what cylinder is misfiring...

I'd bet dollars to donuts it's an injector failing or has a bad o-ring for example. Could be that simple.

JohnandMindi

Is there a way to know which cylinder is misfiring? The Autozone tech said it is a random multiple cylinder misfire code.

Is there a simple way to test the coils or injectors?

maxharvard

You'll need a scan tool or a laptop with the correct software to determine that.

It is also entirely possible you have a fuel pump that is failing, but that seems less likely.

Looks like you have only 3 coils, meaning 1 coil per 2 cylinders, could very well be one of the coil packs has crapped out.