When it's cold outside and I brake hard,the engine wants to stall for a second and shakes violently and then goes back to normal idle,any idea what could cause that,I have no idea,thanks guys !

 

Need some more information on really what going on.
First, year of car, how many miles, and what recent maintenance have you completed?
Automatic or manual transmission? Any CEL / warning lights?
Have you scanned to see if there are any fault code present in the ECU's memory?

The braking action is helped by a vacuum pump that's attached to the camshaft of the engine.
I'd check to see if the brake line from the pump to the master cylinder has a crack or loose connection.
Does it only do this when it's cold?

- Erik

 

It's a 2005 auto with steptronic,112,000 km or 70,000 miles. I did my last oil change a few months ago and no major service eversince. It's doing it mostly on cold days,it's winter here in canada,and seem better as the engine warms up but it takes about 15 minutes or so. I have no codes so I didn't plug a decoder,no lights in the dash,everything else works fine,anymore ideas,thanks

 

With a 2005, you're in the wrong sub-forum; this is the 2nd-Gen (2007+) subforum.
You'll want to either have this post moved or repost in the correct 1st-Gen subforum.
The 1st-Gen owners will be able to provide better assistance; good luck!

- Erik

 

Will repost,thanks Eric