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.
if when its cold and runs at a high idle like normal, and then when it reaches operating temp it starts to fluctuate in the revs. (up and down from 900 rpm to around 2500 rpm) you will find that the engine management temp sender is faulty. To ensure this is the fault. When its doing this and at normal running temp. stop the engine, Disconnect the battery for a couple of minutes. Reconnect the battery this clears all the codes stored buy the computer. Start the car while still at the normal operating temp. If the problem is gone it is the sensor i have previously stated. This sensor can be found on th back end of the cylinder head its a two wire sensor. I hope this has helped.
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,
Has it always behaved the same? It has sensors that detect engine temp, outside temp, humidity and altitude to give you the perfect fuel air mixture for the conditions. 1300 to 1500 rpm is not unusual for cold engine warm up. You could have a bad sensor, but the codes should have revealed that problem. 10 minute warm up is not outside the norm. at idle, but 7 miles driving should make it happen a little sooner. As for the the stick moving when you "get on it", that is normal engine "torque", your engine mounts give just a bit to allow movement and to keep that "torque" from being transferred to the body/framework of the vehicle. You have hard rubber mounts. As they "fatigue" you will notice this movement increasing slightly.