w6grace

Greetings,

I just picked up a nice 99 Boxster. The car had a CEL that turned out to be an issue with the ECU not sending a signal to one of the vario camshaft solenoid. I had the ECU fixed and no more CEL, however there is a persisting idle issue that I can’t seem to solve.
When the car is at idle the RPM is continually fluctuating. Idle ROM seems to be around 790, and varies up to 40-50 RPM. I had my mechanic look at the car and he is telling me it is “normal.” It seems to be more variation than I would call normal. I have had the oil changed, cleaned the MAF, ran injector cleaner and nothing has made a difference. The car runs amazingly and I have put 5,000 miles on it with this annoying issue.
Please advise if there is anything else I can clean before take it to my nearest Porsche shop (not close). I was considering cleaning out the TB. The car just went through 45,000mi, one owner. I am hoping this is not a major problem; my last Boxster had a massive IMS failure within 200 miles of me buying it.
-Will

Ahsai

Welcome. You may want to clean your idle stabilizer and throttle body.
Try the Boxster forum for more suggestions

w6grace

Is that the small black electrical box on the side or the throttle body? I took that out and cleaned it with MAF cleaner a while back, that didn’t seem to help. What sort of cleaner should I be using. I noticed it has a paper gasket that has a rip in it; maybe a tiny air leak there is causing my problems? I may try to make a replacement gasket, or see if I can pick one up on Amazon or something.

Ahsai

Yes, that's the part. MAF or Carb cleaner should be fine. Air leak is definitely a common issue but it's kinda hard to track down by yourself especially if the leak is small, which seems to be your case IF air leak is the issue. Yes, any leak after the MAF sensor will give you problems. Spec rpm is 700 +/- 40 so 790 is definitely not in spec.

w6grace

Yeah, I didn’t think it should idle so high. It occasionally (once a week) manages to get itself to a idle around 700 and it sounds great... Then at the next stop it’s back to somewhere between 790 or as high as 1100.

I will pull off the TB and clean it and the stabilizer tonight. Thanks for all the help.

-Liam

Soaringman

Could be lipstick or eyeliner pencil rolling around under the gas petal from the previous owner.

Please forgive my bad jokes

kromdom

OP, welcome. Here's the link to that forum in case you missed it when you were searching

https://rennlist.com/forums/boxster-...-986-forum-67/

w6grace

Oops... I thought I had posted in the Boxster forum...

No worries, I removed the eyeliner and lipstick.

Soaringman

Ha ha, don't take me too seriously , boxster is a beautiful car

w6grace

It is a fun car. For the $10,000 I paid, I can't really complain.

I installed the rear speaker kit last night instead of doing the TB.

Imo000

Pull the idle air controller off again, apply some power to it so it opens (9V battery) and then use some carb cleaner and a dental pick and clean off all the carbon from the plunger.

I'm in the middle of fixing my PCM because one of the vario cam solenoids aren't being triggered by it. How much did they charge you to fix yours (the PCM only)?

w6grace

I pulled the TB and cleaned it (it was really dirty). Cleaned the idle air controller, reinstall and..... Still the same.... Maybe slightly smoother, but idle is still just a hair below 800, sometimes right on 800.

I think they charged me $800 to fix the PCM, my mechanic sent it to Florida to be done. There is a place in New York that looked at it first but sent it back as "no repair needed." The place in Florida also required the immobilizer to be sent in with the PCM. If you want I can get the contact info for the place in Florida, they were quick and professional.

w6grace

So I am looking at the idle controller. How big of a gap should there be where the little metal actuator is? It seems rather large, maybe about half open. Maybe I need to submerge it in cleaner for a while to get some of the crap out that I cant see. Seems it could be slightly stuck open. I cant seem to find a picture of what it should look like when "closed." Anyone have a picture of a good one?

Imo000

Thanks for the info but I'll be fixing it myself. Just wanted to know how much someone is willing to charge to change an $8 part.

w6grace

Yeah, I wish I had known you back then...

Just took out my IS again and it is soaking. It already has closed a little more than before... or maybe that is wishful thinking... Look like it stays open about 1/8th of an inch.