Weird idle

[ILikeMy240sx]

96 240sx OBDII 78k miles

This never happened before and it only happened for a short time. The weather outside was pretty cold... I parked the car/turned off the ignition whne everything was running fine. I came back after 10 minutes or so and started her up. All of a sudden my idle jumped to 2000 RPM then dropped to 1000 then I started driving. As soon as I was in neutral and idleling. It would steadly climb up to 2000RPM then drop down to 1000RPM then again climb to 2000 rpm then drop again... then it would repeat...

After few minutes of driving idle was back to normal and hasnt happened since

What is wrong? Is there something wrong with the enging temperature sensor?

[s13sr20chris]

that sounds kind of like the famous ka24de intake gasket leak. try spraying down the intake manifold with carb cleaner with the engine running and see if the idle changes.

[MECPInstaller]

not trying to hijack but mine will do this right when slow down to a stop. the engine surges from 600 up to about 900 for afew seconds before it levels itself out around 700rpms. So the carb cleaner to the intake manifold will help this? sorry once again for the jack

[JoeKansas]

The carb cleaner spray won't be "helping" the problem, it just helps you detect leaky intake gaskets. If there is an intake gasket leak, the carb spray will get sucked in this leak and noticably change the way the engine runs- enough so that you will notice it right off. Get enough carb cleaner in there at once and it would make the engine sputter and die- if you don't throttle the engine up real quick and make it come out of it......