Squealing (? belt) noise on reversing when wet and hesitant start

[claudiu]

Dear all,

Hello, this is my first message to you...I'm in love with my first 911. I've experienced only 2 problems in the last 6 months, otherwise I am extremely impressed with my "mistress". I wonder if anyone has experienced a squealing noise coming from the back for about 10-15 seconds when one starts the engine from cold and it's raining heavily or one has just used a pressure washer to wash the lovely 911 Carrera 4 (year 2000) tiptronic. The squeal starts when putting the gear lever in reverse (as I have to reverse first to come off the drive), and I suspected that the belt was causing the squeal by slipping. There was no noise in "park"on starting or when the weather was dry. I had the belt replaced by the dealer and for a couple of months there was no noise, but this morning, after a stormy night and a lot of rain, it happened again. Please help!

The second problem was a hesitant start from cold (even stalling altogether on 2 occasions) after cold nights (minus 2 or 3 degrees centigrade), with a lot of smoke and noticeable smell of unburnt petrol. The garage changed the air flow meter (although thier computer diagnosed faulty lambda probe), but the problem reoccured, then they changed the spark plugs and the problem still occured intermittently till they advised me to help out the engine on starting on cold mornings by pressing the throttle pedal to rev the engine a bit and all seems ok now. I was also advised, much to my delight, to drive in a more sporty style...

What are your thoughts please?

[Loren]

How old/how many miles on the belt?

They are fairly inexpensive and take about 5 minutes to replace.

If the smoke is black then that is un-burnt petrol. On egas cars like yours the idle is set by the throttle butterfly opening just a slight amount (older cars used a idle valve that let in a certain amount of air). When the throttle body and butterfly get carbon buildup the distance changes and the idle/startup becomes rough. Look through the forum here for tips on cleaning the throttle body - it has been discussed many times.

[claudiu]

How old/how many miles on the belt?

They are fairly inexpensive and take about 5 minutes to replace.

If the smoke is black then that is un-burnt petrol. On egas cars like yours the idle is set by the throttle butterfly opening just a slight amount (older cars used a idle valve that let in a certain amount of air). When the throttle body and butterfly get carbon buildup the distance changes and the idle/startup becomes rough. Look through the forum here for tips on cleaning the throttle body - it has been discussed many times.

Thanks Loren for the swift reply. The smoke is white not black and I was actually waiting to hear about the "squeal" when reversing and, secondly, if it's common that one touches the gas pedal to help starting a 911?

How old/how many miles on the belt?

They are fairly inexpensive and take about 5 minutes to replace.

If the smoke is black then that is un-burnt petrol. On egas cars like yours the idle is set by the throttle butterfly opening just a slight amount (older cars used a idle valve that let in a certain amount of air). When the throttle body and butterfly get carbon buildup the distance changes and the idle/startup becomes rough. Look through the forum here for tips on cleaning the throttle body - it has been discussed many times.

Thanks Loren for the swift reply. The smoke is white not black and I was actually waiting to hear about the "squeal" when reversing and, secondly, if it's common that one touches the gas pedal to help starting a 911?

I forgot to add that the belt was changed very recently. The car has clocked 38,000 miles.