One of the first things I installed on my 348TS was a pair of hyperflow cats. Before taking the car for a weekend run, I always let it idle for 5 minutes....but suspect doing so without the garage door wide open would probably kill.... as the exhaust fume build-up is *really* bad. (no smoke...but the smell is far stronger than my day drive Benz) Begging the question, do hyperflows have to be hot, in fact quite hot, before they catalytically convert? or perhaps this is an impending O2 sensor problem? Any thoughts/experience here most welcome !
all cars run rich when cold and you really need to have the door open when you leave the cars idling like that.
Sorry nothing recent.... but will post some soon. Yes the Oz market is in turmoil with cheap UK 360 imports due the high $A.... but I figure cars that have been running on roads covered with salt + snow and ice will have corrosion problems for their new owners .
I assume you are idling the car with the garage door WIDE open (not clear from the first 2 posts???). I have a 355 with hyperflow cats and I start it once a month in the winter. I let it idle for about 5 minutes then run it at fast idle (roads too salty for a drive) until both fans come on. The car is running for about 20 minutes max and during that entire time (in my garage with the door open ) there is NO strong exhaust smell at all. Something does not sound right with your car as the hyperflows should not 'stink' as described above (assuming you are idling the car with the garage door wide open).
On the 355 air is air pumped into the headers on cold startup (first few minutes) that helps burn the rich fuel mixture.....this pump makes a very distinctive high pitched whistling noise. You may want to check if this is operating on your 348 as this could cause an overly rich mixture on cold startup.
My hunch is the same.... I suspect the car still has the set it originally came with.....ordered a new pair of sensors yesterday- pick them up next week
Could be bad O2 sensor, as stated. Could also be a non-functioning air injection system. My air injection pump is fried (corrosion, I think) and is non-functioning. I get the same smell OP is describing for the first 30-60 seconds when I start my 355 up cold. After that, cats seem to warm up and work just fine, no odor. Not too big a deal if you can live with it, as emissions testing only occurs on warm, running engines. (That is if you are even required to get smog tests, depending on where you live.) John
