2002 Porsche Boxster CHANGE OF IDLING RPMs

MELVIN588

MEMBER
2002 PORSCHE BOXSTER
6 CYL
2WD
MANUAL
42,000 MILES

Any input on the below problem:

I was driving the above car in the city when the engoine hot light came on. I stopped and after a while open the radiator and put water into it. The temp light went off and the temp dropped back to normal. @ Days later the same thing happen again. I had the car towed to the Porsche dealler and they checked the raditator and said it was fine but they found air in the system. The car was due for a major serv so I had them do it. After I picked it up I was driving home and the "check engine light" came on. I took it back and they only found again some air in the system. I was driving the car home today and all was fine untill I stopped at a red light and the engine idlle dropped to 4000-5000 rpm making it seem like the car was going to stalll but did not and slowly settled at a normal idle of 8000 RPMs. I am only having this problem when the A/C is being used, when the A/C is off no problem the car runs fine. The car has had the air flow sensor checked and it was OK. I am now awaitng another appointment at the Porsche dealer.

2 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

To startt off, does it still get hot? Or isit running at normal temp naow. If there is still air "appearing" in the cooling system, it can cause the Coolant Sensor to give false readings which can make them run poorly or different. The Coolant sensor cant read air, so it may be trying to adjust mixture for a temp it cant really even read. You may also need to clean out the throttle bore around the butterfly. Over time "Coking" will build up around the butterfly changing the set minimum air that is allowed in, which in turn will effect the idle stability.

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Thursday, July 29th, 2010 AT 8:03 AM

CWPORSCHE

MECHANIC
58 POSTS

You need to find out how air got into the system in the 1st place. There may be a coolant leak somewhere that is not obvious, i.E. Under the carpet in the rear trunk. Coolant tanks crack after a period of time and slowly leak under there but not on the ground. The coolant light won't make the check engine light come on unless it was severely overheated and this is probably not the case. They should have been able to tell you why the check engine light was on when they serviced it. Also have the throttle body cleaned and that will likely take care of the surging idle. You have multiple issues here that a reputible Porsche dealer should be able to correct. Hope this helps.

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Friday, July 30th, 2010 AT 10:46 AM