When the outside temp is in the upper 80,s+ and the car has been running under load for 30-45 minutes with a.c. or not.the idle sometimes revs up to the 2,200 2,600 rpm range. it does not do it consistently.there are no codes or check engine light on when this occurs.i've changed the tps and the iac still no change.sprayed contact cleaner all around everything searching for an air leak, no fluctuation in idle.checked coolant temp with scanner and it's ok.
any ideas? a hose colapsing ? other sensor ? ?????????????????
Check the inlet air temp sensor. It should be located near the airbox but before the throttle body. This unit does not show in code. It registors the outside air temp and adjusts throttle and fuel mixture to match. If the sensor id faulty it will show as being cold and set the throttle for cold starting and running. Check manual or Autozone for multimeter ohms check on this unit.
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QUESTION: 1991 Sedan Deville, 4.9 port injection Car runs great until outside temp reaches 92 deg. or above. the car will start to cut out under load (take off or hill. if i pull over the car will idle fine rev the engine to a steady high rpm and it will cut out. i had a code e44 (o2 sensor rich)so i replaced o2 sensor with no effect. the other code received was f85 (Throttle body service required). I have checked all connectors and hoses attached to the throttle body. all ok. looking inside throttle body there ar two tubes under the flaps one is totaly restricted with a black buildup and the other partly blocked. Not sure what these tubes do and if that could cause engine to cut out when hot and under load. any ideas?
ANSWER: You found your problem which is this black residue which when hot turns to a jelly substance and blocks the idle air passage. You need to clean all that residue from the throttle body and do not forget to spray the small hole in the side of the throttle body just behind the throttle plate.
This sounds like you have a pcv hose that has become an open vacuum leak. It is located under the upper intake, or given the year your air filter box may not be correctly sealed and possibly have a mass air flow sensor concern. Any Check engine light or codes to work with ? I f you have further questions just leave a comment on my page,