Hi all.
I have an '08 987 Base. The other day while at a stop sign, I noticed weird idling behavior. I usually idle around 800-1000; however, it started idling around 1600. A quick blip of the throttle will settle it down, but then it goes back up. I drove home, parked it for a few hours, then drove it again. It started again after roughly 15-20 minutes of driving. I’ve seen some posts about being a new MAF, but also some about a throttle sensor. Any ideas? Oh, no codes either (yes, I know the lights on the dash. I needed air in one tire, and the other light is the car throwing a fit because an LED bulb). See video link. Thank you!
I would look for a vacuum leak somewhere. I would expect a code but you arent getting one, so perhaps look for a leak before the MAF. If I were troubleshooting my thought process would be:
In order for a code to appear, the O2 sensors would detect more air than what was measured by the MAF, therefore more fuel needs to be added. If there is a leak pre- maf, the extra air is accounted for, but because there is more air, there is also increased RPM. Also a reason why you see this after 15-20 mins is as the engine warms up, it breathes easier. Also take a look at the idle control valve if these cars have one, it might not be closing as expected. On my other cars, one way to test is to check resistance on the valve, for example on my other car I am expecting a resistance of 3 ohm, but I saw 13 ohm, that tells me my valve has a short. I dont know if the 987 has one and if it does, not sure if it can be tested in the same way.
Fantastic. I'll check everything this weekend when back home from work travel.
Thanks so much for the guidance.
Those are sort of classic symptoms of an intake air leak, especially blipping it, return to normal RPM then creeping back up again.
This model
Porsche
doesn't have an ICV (Idle-control-valve) - the electronic throttle body makes them unnecessary. A smoke test might be in order - try to locate the leak. There are plastic accordion like hoses all over the intakes, and those are known to not age real well.
BTW - a reading of 13 Ohms when 3 Ohms is expected doesn't indicate a short. A reading of 0 Ohms would intake a short. The 13 Ohms indicate some resistance in the path, possibly due to a dirty or bad connection.
Thanks for this. I'll be doing a smoke test (hopefully) this weekend.
