Hunting Idle

[slithern]

Hello all,

I have researched this extensively but am still coming up short on an answer so here is my issue:

2000 Boxster 2.7
80000 Miles
Tiptronic

The idle is going up and down from about 600-800 when in Park. If i am just at idle speed with the car in Drive the idle is a little rough but nowhere near the bouncing up and down.

It doesn't happen when the car is cold and first fires but as the idle settles in, it starts the issue.

There is NO Check Engine Light

Air conditioner on or off doesn't change it much at all.

I can pull the oil cap off easily and the car idles terribly when i do, so no vacuum leak in the crankcase and AOS is probably OK?

The MAF was replaced to try and solve the problem a year ago and it seemed to be better but has since gone back to the issue. ( I don't drive the car much)

I added a bottle of fuel injector cleaner today to see if that helps.

The care seems to run fine when moving. This seems to be strictly an idle issue.

I'm prepared to clean the throttle body, clean the new MAF, check the AOS, check the O2 sensors (somehow), replace fuel filter if need be etc. but would appreciate a point in the right direction.

Bill

[Heiko]

Take the throttle body off and clean it really well. Chances are that there is some buildup on the edge of the butterfly as well as on the sides of the tube. You'll have to remove the air intake pipe and then remove the throttle body before it goes into the intake manifold... you can use regular carb cleaner spray (works well) and a clean rag (if its heavily soiled, use a small brush a some gasoline first to get the rough stuff out)
That should do the trick (just a little dirt in that T-Body can make a world of difference!
H

[Jager]

Yep... Throttle Body cleaning.

[Topless]

+1 on TB cleaning. Also have a good look around at vacuum lines. A crack in the tubing could be enough to cause this at idle.

[thstone]

Double check the MAF. Disconnect it and see if the problem persists. If so, then the MAF is ok. If the problem goes away, replace the MAF again.

Check for air leaks (including dirty throttle body which does not fully close/seal and creates a small air leak).

[aussieboxy]

I had the same problem. Cleaned the throttle body & issue resolved.

[Pinarelloman]

This happened within two weeks of me buying mine, I was more than a little worried. Mine also was hard to start.
After cleaning the throttle body all was well. Follow the instructions on Pedros board.

[slithern]

Thanks everyone. Cleaned the throttle body and problem went away. Purring like a kitten.

[coolbreeze551]

I did the same thing; cleaned throttle body, intake tubing, etc... to no avail. Still have idle dip when I come to a stop and then it levels out again... I guess the only thing to do now is to send it to Jake at flat 6 to massage it to 2.9 and put a turbo on it :dance:

[Mrmaddbrad]

Originally Posted by coolbreeze551

I did the same thing; cleaned throttle body, intake tubing, etc... to no avail. Still have idle dip when I come to a stop and then it levels out again... I guess the only thing to do now is to send it to Jake at flat 6 to massage it to 2.9 and put a turbo on it :dance:

Haha, or go have it smoke tested at a shop and fix the leak :P

[bobbyg]

Thanks for all the info guys. I might need to clean the TB also then :-). My Boxster just started doing that two days ago, hunting, and got me worried. I'm still a baby whne it comes to the Porsche cars :-).

Cheers.