ebfox

On a trip last week my check engine light came on; at the same time the car developed a rough idle (it starts fine, but dies when I am rolling up to stoplights, etc.) Using Bill Wagner's excellent diagnostic directions, I have determined that I have a fault code 1115, which means Idle Speed Contact Break (makes sense). No other fault codes are recorded.

I have no idea where the idle speed contact is- can anyone give some direction to an aspiring mechanic (I have an engineering degree, but it is in Civil so keep it on a reasonable level). Thanks

E. B. Fox
91 C2 Targa

Adrian

If you check the thread on this forum called
"ISV, air-flow meter and idle microswitch clean" you will find the idle microswitch which is mounted on the throttle quadrant.
Ciao,
Adrian
964C4

Lorenfb

If you're going to be a DIYer on your car, you need to start out by buying this book,
Porsche 911, Enthusiast's Companion. On pg 139 the idle valve and idle switch
are discussed. You need to do some background reading and not rely on the
forum for all your DIY efforts and problems.

ebfox

Loren,

Thanks for the book advice- I have been looking for a good one. I have a Clymer manual but it does not give me the detail I need.

EB Fox
91 C2 Targa

Bill Wagner

Yes, Loren, but if he never came to this web site he wouldn't have found the reference to the book!!

By the way, what's a "Clymer Manual"? I've never heard of it.

ebfox

Bill,

Whoops, I misspoke. My old manual is a Haynes manual. I have a Clymer shop manual for my Kawasaki.

Thanks for the pdf; I finally got it to open. I am going out of town this weekend- will be troubleshooting my idle problem next week.

This web site is a great idea.

E. B. Fox
91 C2 Targa

Lorenfb

You can quickly check the idle switch with an ohmmeter between pins 52 & 30
on the DME connector without going in the engine compartment. You should
measure less than 2 - 3 ohms with the throttle pedal at rest. A small depression
should "open" the switch.

Kahdmus

Someone get out of bed on the wrong side? Sheez!

E.B - I usually find a LOT of answers by doing a search of the forums before anything else - its a great database to get your research going in the right direction before you start asking questions, reading manuals or talking to a mechanic.

Dont stop asking obvious questions because of the occasional J**k off - many people will be able to benefit from the answers as long as the information is searchable.

Oh - and DEFINATELY invest in a copy of Adrians book - it is invaluable to say the least!

Good luck,

Doug H

Haha, or you could be like me, read the book and still have questions.

Kahdmus

Exactly!! I'm amazed I haven't been expelled or banned by certain members due to the number of times I've repeatedly sought help!!! The generosity and true passion of people on Rennlist never ceases to amaze me!

Lorenfb

If you do some preparation/reading before asking the questions, you probably
will receive more helpful and applicable answers. Members are more receptive
to questions when one has done some analysis on his own versus the typical,
e.g. "My car makes some smoke. Got any ideas?"

Bill Wagner

Speak of the Devil!!!

I just noticed this, not only on my 964, but my Z as well. Every time I start the car, some kind of smoke and odor comes out of the exhaust pipe.....Any ideas anyone?

ebfox

Guys,

After extensive research and half the morning taking it apart, it's fixed- and it was not what I expected.

I first tried the airflow meter/ISV/idle microswitch cleaning procedure as detailed by DavidI. As I was cleaning it up, I was thinking that it was not that dirty- sure enough, I put it back together, reset the DME, enjoyed a "spirited drive" and the check engine light came right back on. Same fault.

CKKrause had posted a detailed graphic out of the shop manual, so I spent the next 20 minutes fiddling around with the idle microswitch. I noticed that if I jiggled it just right, the idle smoothed out and the fault cleared. After 3 or 4 times I noticed that my jiggling was also jiggling the cruise control cable- what was happening was that the cruise cable was holding just enough tension to keep the idle microswitch from making contact! A simple tension adjustment and I am back in business.

Many thanks (in no particular order) to Bill, Adrian, Loren, David, CKKrause, and all the countless others who wrote the myriad of posts that I read.

E. B. Fox
'91 C2 Targa
"Experience is what you get when you thought you were going to get something else"