BPG_Austin

Hello all, I know hunting idles have been discussed in previous forums, I went through them but didn't find anything exactly like the symptoms I have. I have a lower mileage '99, 35k. Idle with drop down to 200-400 rpms when the AC is kicked on. Often rpms drop so low that the clutch will shudder a little. After a few 'bobs' on the tack idle will stabilize and things will be fine. This also will happen when car is hot, coming down from higher RPMs's, though not as severe as start-up. I'm wondering if this idle issue is sensor related or possibly because of a dirty throttlebody? I have cleaned the tb with carb cleaner on a clean rag but haven't pulled it off and thoroughly gone through it. cleaning did little to stabilize the idle. Any suggestions? Thanks.


Ben

99firehawk

BAISCS FIRST

how old are the plugs
hows the air filter look ?
how dirty is the t body ?

cant really tell ifs its sensor related with out a scan tool to read sensor data

BPG_Austin

I did the plugs about 8k ago. I had a look at the airfilter last week and it was in good order. The throttlebody didn't look bad to me when I cleaned it. I couldn't look too far in as I didn't take it off the car. I don't have much experience here and don't know what a 'dirty' tb would look like. Just some light black on the rag after cleaning. I might be way off track, but could there be any kind of varnish built up inside? The PO only drove the car 5k miles in his 5 years of ownership. could this be a possibility? The car had a little hunting idle when I bought it. The dealership did a PPI and diagnostics were all clean. Hastn't been on the machine since. Thanks Brad.

BG

99firehawk

no check engine light now ?
its really hard to day whats going on with out diag infomation. do you have acces to any type of scan tool?

BPG_Austin

No check engine light. I'll be purchasing a diagnostic tool shortly to wipe out an airbag warning light. (seatbelts..). will the durametric reader handle this diagnostic?

99firehawk

i belive so
I have no experience with the durametric only porsceh tester and snap on scanner

BPG_Austin

Well, looks like I'll have to go run some diagnostics. I'll repost when I've got some more information. I'll be ordering the reader unless anyone in the Austin area has one available??? There would be a free case of beer involved!

Ben

cdodkin

Just a personal observation - just because the air filter looks ok, doesn't mean that it isn't restricting air flow.

I swapped out a good looking filter on my 996 and was amazed at the difference this made at idle - replaced with a stock filter of course.

1999Porsche911

I am assuming since it is a 99 that it is NOT EGAS and therefore you should remove the ICV from the side of the throtlebody and spray it clean with carb cleaner. Take a toothpck and make sure the window pivots freely.

deliriousga

No. The Durametric will only give you codes and very limited "live" info. It does not give you O2 sensor readings, fuel trims, etc. The other one I have (AutoTap) does all of that and records it, but it will not clear airbag, alarm or a/c codes like the Durametric.

BTW, if you end up needing an ICV for a '99, I have one I bought on accident that I'd be happy to send over for 1/2 the dealer's price to get it out of the drawer.

Todd Holyoak

That is simply not true. The Durametric gives you all the 'live' data, fuel trims, o2 readings, maf, voltage and air flow etc. Yes you can only stream 8 at a time but they are all available.
Check out their site, if you have a late model porsche it is the tool to own short of buying a PST2.
Also short of the factory tester, I know of no other tool that will allow you to reset the air bag light.

Todd

Loren

Since it is a MY99 my bets are on a dirty throttle body/butterfly and/or idle control valve.
Buy a can of Gumout (or like) and clean it all up.

samluke

I had a similar problem, and mine was a dirty throttle body. The throttle body has to be removed to clean it properly.

BPG_Austin

http://forums.rennlist.com/upload/bgicvalve_copy1.jpg

Ok, first time posting a picture. I couldn't figure out how to post both, so bear with me, I'll post the other in a seperate reply. Here's the idle control valve after I cleaned it iwht some carb cleaner and a Q-tip. It was dirty and did not move smoothly. Lots of crud buildup came out, wow. After the cleaning she opened up smoothly. couldn't get all the dirt out, but most. The thottlebody was pulled off and cleaned as well. It didn't look awful except the upper areas where the idle control valve and the other butterfly-mounted valve sat. This area required a bit more work to clean out. Picture was taken before this area was finished. Put her all back together with good results! Idle does drop a bit when AC is kicked on but nothing like before. From several very helpful PM's this appears to be within normal Boxster specs. The clutch no longer flutters and rpms stay above 550-600. Idle has increased about 100 rpms. Thank you all for the help. Greatly appreciated! Oh, and for anyone who would like to do the above work it only took 2 hours or so at my slow pace. An easy and fun job.

Ben

BPG_Austin

http://forums.rennlist.com/upload/bgtbody_copy1.jpg