I got my 2013 CS4 two days ago and found that it has a strange smell (petrol like) when braking down from relatively slow speed to a full stop. The smell occours about 5 seconds after the stop and lasts about 30 seconds (Aircon on Auto).

First I thought the smell was from the brakes (Ceramic) but now I am leaning towards fumes of gas. It is clearly entering via the AC, since if I enable the recycle function the odor does not occour. I therefore opened to inspect the AC intake/filter and to my surprise I found that porsche has placed the fuel pump straight in front of the AC intake (!). That does not seem to best practice engineering to me..

My theory is therefore that the fuel inside the tank moves upon braking to cause fumes to enter the AC compartment and that the pressure in the fuel system is in this condition (braking at low RPM) "just right" for the fumes to leak out of the fuel system causing this.

Taking it back to the dealer tomorrow (got a headache after driving/inhaling to diagnose this!), but any input from this forum would be highly valued!

 

!!!
Not good at all.
Please keep us updated on what happens.

 

Yes looking forward to the diagnosis. I've got C4S too!!

 

Ok. Will post once this issue has been found. Do you have the Ceramic brake option?

 

Other than PCB and Power Kit...I checked every other box !

 

Dealer had the car a full day now checking it without results. The Mechanic i took for a drive could smell the "fumes" immediatally after starting test drive and stated that "this is not like it is supposed to be". They are still not sure what the smell origins from (breaks, fuel, or other). It has a tint of burned "something" to it. There are (strangely enough) however all sorts of sources for smell in front of the AC intake including battery, EVAP unit, EVAP canister, Fuel-lines, Breaks etc. Later the sales guys told me that they had been out driving and did not smell anything.... Today the sun out for the first time since I got the car and it is in the shop

 

I always drive the car for the senior mechanic to replicate the problem them.

Does it get worse if your fuel tank is full?
If you have the car on a steep decline / incline does it smell?

Just because it seems to be coming through the AC, doesn't mean its not happening further back.
I would not accept this car until they find the source and fix it, which probably means taking it apart to trace the fuel lines.

Please keep us posted.
Thx

 

Hi Dux. Thanks for your insight. The Mechanic did recognize that it was a problem when I drove the car with him but I guess He just forgot how to replicate it for the others at the shop (???). The problem only occours at VERY slow speed and full stop. (indicating that airflow might keep the smell from entering the area in front of the AC intake). This could of course strengthen theory that it is coming from something further back, like the engine, traveling below the car. Problem is mostly present when car has normal working temperatures and not when it is cold. The problem is equal independent on gas tank level. I have not noticed any difference during steep decline/incline. I will repeat that I am not sure if it smells of fuel or something else. Just smells like a mix of fuel and "burnt rubber" I guess. Any other ideas would be welcome. The shop seems clueless : -(

 

It is interesting that the cabin filter sensor did not detect the hydrocarbons. It is my understanding that when the sensor detects exhaust and/or hydrocarbons in sufficient quantity it causes the car to recirculate cabin air

 

Ok. I didnt even know that it was such a sensor. But in this case I guess the smell most be from something else than hydro-carbons (or in such a low concentration that the sensor would not pick it up).

 

Petrol has such a distinct smell (as opposed to burnt rubber) that they should be able to distinguish and separate the two smells.

Have you tried this with someone standing outside the car? Could it be even worse outside the car?

 

The Mechanic thought of that and dived down to smell the front wheel hub when he exited the car. He said he could recognize the smell , but unsure of if it came from the brakes (Ceramic by the way) or somehwere else.

 

Got the car back today after the shop (official Porsche center) had it in for two days. After the initial drive when I had the mechanic by my side, where he clearly acknowledged the problem I left the car with them and they had after this driven half a fuel tank without beeing able to replicate it (!). So they called and asked if I wanted the car back for the weekend so I would be able to check if the problem was still there. I got the car and drove off and after 30 seconds I pushed the brakes to a full stop and I could feel the smell again. Checked with my Wife and she could also smell it. During that 10 minute trip I was able to replicate the smell during every stop I had with the car. I find it very strange that the shop could not find it once after burning through half my fuel tank and having my instructions on how to replicate it. Afer more concideration it definately smells more burnt than petrol. The car was driven as a shop demo car before I got it and I now fear that the engine is leaking fumes and burnt oil that leaves odors traveling below the car towards the AC intake when doing a full stop. I have given them 1 week to fix it before I will ask for a full refund.

 

I opened the windows today when stopping at a light and Yes, it appeared to be worse then.

 

The only time I smelled something like that was when I performed a launch control on demo car. The salesman said that was pretty standard, but I wondered about it.

ChuckJ