ok so i kinda just joined here but i've been an enthusiast for a while.
I have a 2001 volvo s40 1.9t its nice i love it but theres a problem
for some reason everytime i floor it black smoke comes from under my car.
(or thats what friends say) my check engine light starts to blink at around 4000 rpms. also when its at around 4000 rpms the car shakes like theres something wrong with the turbo. its like when the turbo spools faster it just starts to jerk. i dont know if anybody has had these kind of problems before
does anybody have any ideas?

 

Check the spark plugs,coils and wires.

 

check the engine mounts as well...

 

i forgot to mention that you get a loss of power too, so its not really the car shaking, but the engine kinda jerking. its kinda hard to explain.

 

more than likely you need a thorough tune up!

 

The black smoke is un-burned fuel...
So you need more air/spark.
Like above, a tune up is a great start!

 

+1, if you haven't had a tune up in a while... Can't hurt PLUS it's one less Variable.

 

I'm gonna bet misfire.
based on the fact that the CEL blinks at WOT -- very common sign of misfire I believe (do you concur tech)
everything I have read about misfires say that.

check plugs, coil packs for cracks/wear, and plug wires

Good Luck!

 

+1 on that.

 

So did you ever find out what was happening?!
Don't leave us hanging here!