I have a 2001 996 tip with 40k that has developed (or I just noticed) a slight idle issue.

In gear stopped I can feel a slightly rhythmic pulsing but the rpm is very steady- it is the same in park as well. But if I just touch the gas to bring rpm up to @ 1000 it pulses up and down @ 200rpm each cycle. The car drives normally and it is not something that affects drivability but wondering what it is.

New air filter, new fluids, well taken care of and no codes popping up. Top tier gas used, and no oil usage between changes at every 5k.

Should I try a spray cleaner into the throttle body to see if any buildup - but it looked very clean when I changed the air filter recently. ICV possibly or an intake leak of some sort - what is the best way to test this?

Thanks for any ideas to resolve this minor issure - before it might turn into something larger...


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I think the AOS(if on its way out) can cause some smooth idle issues, others will pipe in no doubt.

 

Can also be an O2 sensor getting ready to check out. The sensor will trip the cel when it does completely give up.

 

Clean the sensor right before the intake that is attached to the air filter box.

Don't touch it. Just use the spray in heavy amounts like instructions say. Fastest first check to do.