Thanks

Dave

I have the same problem with my 2000 boxster but mines has gotten worse. My engine RPM flactuates on idle non-stop. It goes down to around 600 then shoots to 800 then 700 then repeats continuosly. I have taken it to many shops but no one seems to know what the problem is. I replaced so many things already that I might as well build a boxster from scatch. I replaced the Mass Air Flow sensor to no avail. I was thinking that it might be a vac leak but from what I have been reading here it sounds like a softaware issue that will never be resolved. Good Luck to all.

Regards,
Ivan

The idle is the same. I remember that the idle went haywire after the installation of the mass air flow sensor.

Is there some type of special mapping that should occur after the sensor is replaced? It does seem to be linked to the sensor.

Any information would be much appreciated. I love this car, otherwise it is faultless.

Sorry I wasn't more clear. Cleaning the valve did not change the frequency of occurrence but it did minimized the severity (the RPMs did not drop as drastically or overshoot quite so much.) As for long-term durability, there are zero concerns there; it will have no long-term impact on durability. Trust me, I've had the problem for 8 years! It's no different than taping the throttle plate or, really, even from normal idle. Annoying? Yes. Damaging? No.

One major change that would help eliminate the problem would be the upgrade to a larger displacement engine. More displacement means more torque at idle and less susceptibility to accessory load fluctuations. Yes, I'd love to have 3.8L 911 engine dropped in my Boxster, but I have to be realistic: it's never gonna happen!

Thank you for your prompt response. After reading your story and doing some research around the net, I don't have much confidence in ever being able to resolve the problem. From what I have read on the problem at http://www.986faq.com/10-0/problems.asp#003 PCNA has not even admitted that there is a problem. Customer service in my country is a lot worse than it is in the US and I doubt they'll do anything about it here.

While my problem is essentially identical to yours, there is a slight difference in the RPM at which it occurs. My normal idle RPM is 700 (maybe even a whisker under 700), not 800 as is the case in your Boxster. It goes down to 600 (exactly as yours) but recovers and overshoots to 800 (not 1,000 like yours) before settling back to the normal 700.

When you say that cleaning the idle bypass valve minimised the problem, do you mean it reduced the severity (RPMs drop less and then overshoot less) or the frequency of the problem? Also, do you know if the problem causes any long-term damage to the engine? If not, I guess one can simply learn to live with it.

Thanks again.

Ranesh

I have not managed to completely eliminate the problem. I did minimize it by removing the idle bypass valve and cleaning. This is a small, electrically -ontrolled rotary gate valve that controls the amount of air that is let around the throttle plate at idle. So, if engine speed starts to drop, the valve opens up, allows more air, which in turn allows more fuel, which finally raised engine idle speed. My idle bypass valve had a lot of carbon deposits on it that I manged to remove. I thought I'd found the final solution, but it did not totally eliminate the problem.

You may want to give this a try. As I remember, it was very easy to remove (2 bolts) but there was a paper gasket that was not very durable. Also, my Boxster is a version that does not have the electronic throttle pedal / throttle plate. Your's does have the electronic throttle controls (Porsche calls it E-gas.) I'm not sure, but the electronic throttle plate may completely eliminate the idle bypass valve (since the engine computer controls the throttle plate, it may eliminate the need for a second air flow control device.)

This has been the one frustrating problem I've had with my Boxster that I've not been able to solve. I'm sorry to hear that you are having it as well. Best of luck resolving it and please let me know what you find.

-Carlton

It seems I have the exact same idle problem as you do on my 2004 Boxster which I bought in January 2007 with less than 20k miles on it. Of course, I only noticed the idle problem in March 2007 when I started using the AC. (In case you're wondering why I would start using the AC so early in spring, I live in Dubai, UAE and it gets warm early here.)

I'm wondering if you've finally managed to fix the idle problem. If not, do you know if it causes any long-term damage to the engine? Or is it just an irritant that one will have to live with if one was unlucky enough to buy one of the affected Boxsters?

I'm just beginning my effort to try and fix this problem. If I meet with any success, I'll be certain to keep you updated.

Thanks.

Ranesh