Started my car and it was running rough. The "Check Engine" light was flashing. Seems to be running on three cyl.. Also noticed a sulfur smell coming from the engine. Any ideas what's going on with it? Thank you!

 

Welcome to the Forum!

We need more information please. When is the last time a tune up was performed? Did the engine smooth out after awhile? Did you shut it off and not restart it? Any work performed on the car lately?

The flashing check engine light is telling you what you already know with a severely misfiring engine. I ask the above questions to get an idea where to look first. Normally, a misfire is the engine telling you it needs a tune up. The sulfur smell I'm not certain about. I've always associated that smell with the cat convertor.

 

That's what is crazy,ran fine going to work,went out after work started it up,was running rough,like on 3 cyl.check engine light flashing.Shut it off for 1/2 hr.restart,same thing,so I drove home easy.Car seemed to have no power, so I easied home about 45mph,and at times would smell the burnt match smell,my son followed me and said he smelled this smell also behind the car.Now this car has a new top end that was do to a broken timing belt,(and you know what that does,) just 5000 miles ago,plus we did all the little things you do while you are that deep into a repair.all done by a very good shop. I consider myself a decent mechanic,only on cars prior to 1985 after that to many computers,sensors.I myself think the smell is from the cat. system,but that dosen't explain the rough running,maybe the timing is off,causing the roughness and firing at a different time causing the gases to be diferent in the cat .system.I know that this engine has the variable timing,so maybe that sensor,pitched.See got to have a computer to tell you what code is going off so you know where to start,or a diagram of all the sensors to unplug / plug to start your hunt.

 

Probably faulty o2 sensors which will damage the cat if bad enough.
Can you get the fault codes read. That will show up a list of faults relating to the cat and /or the sensors if it is that.
If the cat is badly clogged up it will cause the engine to run very rough as you describe.The honeycomb materials within burn out hence the extreme smell.
Has the fuel economy been worse or late?

 

It's a bad idea to drive a car with a known misfire. If the fuel injector is firing all that fuel winds up in the catalytic converter where it is oxidized - i.e. burned. Cat gets red hot and can set your car on fire. Many years ago I nearly lost a Saab that way. It's not easy to throw water onto the bottom of your car.

As far as the misfire goes, read the codes. Then hope it's not a burned valve from a botched head rebuild.