Hi guys... just wanted to see if anyone has an idea on this new issue I’m having. About a week ago I noticed my S is starting very rough. The car starts but shakes and rattles to the point it’s almost frightening. This morning when I went to start the car it bucked and shook like I was experiencing an LA earthquake before it SLOWLY started to come alive. And I mean slowly it started to idle up and up....then I let out on the clutch as I was in neutral and the car almost stalled until I gave it gas.

Once it starts it drives wonderfully. Accelerates and drives like a dream. I’ve made no recent changes to the car other than going full synthetic on my oil, but I can’t logically think of any reason why the oil would cause this behavior. Every 3 months or so I run Techron or Seafoam through a full tank of gas and only use Shell 93 to fill up. The car has 85K and I did the plugs around 65K. I'm religious about oil changes and the oil level is fine, I checked.
Any ideas on what this could be? I know I do need a new battery before it gets really cold out but otherwise I'm stumped as to why the car is doing this on starts.

 

I'm experiencing the same exact thing, it sucks the whole car shakes really bad

 

Motor mount possibly

 

Iacv? Search on that, sounds like a similar issue. I've never experienced the issue so that would be my best guess. What year?

 

It could be a number of things. You should start going through a process of elimination. I'm assuming you don't have a CEL.

Do you see more white smoke than normal coming from your tailpipes at startup? Losing coolant? A leaky head gasket could cause this.

Check your plugs right after the problem occurs. If you have one plug that looks very different, let us know. It could be oil fouled, or you could have a leaky injector.

I doubt that it's a bad coil pack, but you can't rule it out. I'd think a bad coil pack or plug would throw a CEL.

You may want to clean out your throttle body. This may be a longshot but it can't hurt.

If all else fails, consider doing a compression and leak down test.

 

I posted up about my car doing that only after it sits for about 3-7 days. It starts fine throughout the day and even after 24-48 hours, but if the car sits for longer than that it starts rough.