RichiRich

I've noticed recently that when I push hard on the accelerator (gas) in my 964 Turbo, I get a puff (smell) of exhaust fumes in the car (with windows shut, but fan on) - any idea why? Under normal driving I don't get any.

Rocket Rob

Was your heat on? The heater draws its air from the engine compartment. If you have any exhaust gases in the engine compartment, it will be pushed into the cabin.

elbeee964

Don't forget the obvious leak path - leaking exhaust manifold/heat exchanger.

(though how one would test for a leak there is beyond me.)

springer3

Any after-market exhaust parts? Is the cat still installed?

Exhaust contains carbon monoxide which is dangerous even at very low concentrations. If you are getting whifs of exhaust smell under hard acceleration, you are probably getting lower levels all the time. I would be taking this seriously.

RichiRich

Heat was set to '21' and fan was set to '1'. I generally drive with the sunroof open, even in the winter, so I'm not so worried about the CO - though it is a consideration now that you've mentioned it.

I have a 'maxi-flow' exhaust/muffler (but am not sure who makes it) with the main cat still attached, but the secondary ones have been removed as I understand.

crg53

My guess is you have a leak in the power steering pump drive where the cam shaft comes out of the cam tower. Mine did exactly the same thing, and changing the seal and the o-ring fixed th problem, also cut my oil consumption in half. The drive is located in such a way, that the oil drips right inside the heat exchanger, and you will get a burnt oil smell in the car and especially under hard acceleration.

RichiRich

Thanks. Was it a relatively cheap fix?

springer3

Burned oil smell is a different problem from exhaust smell. If you have oil smell, you have an oil leak getting to the exhaust and smoking. If you are smelling exhaust fumes, you have a crack or hole in the exhaust letting the exhaust get into the heater boxes. Cracking is a common problem with after-market exhaust systems.

Oil leaks are a relatively cheap fix, most of the time. Replacing or repairing the exhaust system is not.

RichiRich

Maybe I need to smell it a little better as I'm not sure I know the difference between exhaust fumes and burnt oil - to my embarrassment. I would sometimes have likened the smell to an extinguished match (when it's still smoking) - does that make any sense or am I just confusing you all?

I think it best that I just take it to my indy and get them to look at it. Thanks all for your help/suggestions.

springer3

There is no mistaking the smell of burning motor oil. Put a drop on the exhaust after the car has been on a hard run.

An acrid smell like the the fumes from a recently extinguished match is probably exhaust. Unless I am mistaken, the heater boxes are up-stream from the cat, so you will have the smell of unburned hydrocarbons. You will also have carbon monoxide, which does not smell.

Frank 993 C4S

I have the same issue, except that my smell is definitely not burnt oil but more like fuel and it only happens under boost. I wonder whether the above is the explanation for it or whether it is just running waay too rich. Will check.

Do you have headers?