Ignition switch replaced... still no dice.

[JebLacey]

Car starts so intermittantly, its not even funny.

It was starting fine today, but I replaced the switch anyhow. Took it for a drive, and sure enough, after about 15 min. of driving, it just died while on the road. Trans. went to safe mode, and when I tried to restart, no dice.

Questions...

This problem started immediately after I washed and filled up the car a few weeks ago. After a few days, and perhaps a quarter tank of gas, it stopped all-together and was driving normally every day. Then, when I got the car down near empty, it started again. It happens while rolling and while in park, going to safe and dying at the same time. It never goes to safe and stays running, it always dies, so I know the problem is inter-related. Also, when it goes to safe (flashing between the d and 4) the CEL is not on like it should be. Then, when I roll to a stop, the CEL obviously wont come back on. I dont do anything to get it to start again. Just leave it alone for a while (almost like it is cooling down), then the CEL comes on at ignition, it starts, drives fine until the temp gets up around 190ish, then dies again and wont restart for a while.

Could my problem be related to temperature..., i.e. computer getting hot and shutting down?

What about water... where are the grounds related to this whole system? I checked the #8 and #9 grounds today (the ones on the back wall of the rear compartment) and they seemed fine.

Does anyone have a full relay assignment listing for the relay panel under the dash? I only have a partial one on my "alldata" subscription... There are quite a few relays that are not listed, and I would like to know what they all go to.

Lastly, there is supposedly a large distribution center for all the electronics somewhere in the front passenger side of the car. Has anyone ever accessed this, and is there the possibility of water or something in there? I only ask because the starting problem began after I washed it.

Is there any special way to disconnect the battery? Should I do it w/ accessory on? Then turn off the key?

What about buying an aftermarket or used DME? Are they available out there?

Sorry for all the questions.... :(

[Loren]

One Tiptronic ground point is located in front of the instrument cluster on the dashboard support frame.

The other Tiptronic ground point is located on the rear wall in the rear luggage compartment, between the DME control module and Tiptronic control module.

There is also a connector that should be checked for corrosion or loose pins.

Plug-in connector X 2/6 (21-pin, blue) is located beneath the convertible top on the right-hand side member (in

the vicinity of the lower safety belt attachment).

[JebLacey]

Loren:

I found the first and second points you mentioned.

- the one under the dash and the one on the back wall. However, the second picture (supposedly of the back wall one) shows one that is near the strut tower. I cannot locate this ground. There is a black film that is glued down around the tower, and I am nervous to pull it up. Is this where i should be looking? Also, I could not locate the plug near the passengers lower seat belt... is it beneath thte carpet? Or are you refering to one of the plugs in the drivers side, rear wall of luggage?

Also, do you know relay assignments for the under-dash relays?

Lastly, i learned somehting new about my prob. last night. When the Key is at Accessory, the motor itself (sounds like the throttle body) makes an electronic humming noise. This noise is present until the key is removed. however, when the CEL does not come on, the engine does not hum. What is causing the electronic sound, and how could it be related to my problem?

Really truly Lastly, this motor is freakin dirty! It is perhaps the dirtiest motor i have ever seen. Is there any major grounds or distribution points in the engine comp. itself that i should clean/check? What about the maf? Has anyone ever heard of the MAF or any other sensor causeing a no-start, to include no CEL at Accessory?

Honestly, does anyone know where the CEL at accessory comes from? Like, what system, via what switches/wires? I am thinking that maybe if I start at the source of the CEL and make my way back, I may find my problem. For example... if the DME decides not to start the car, how does it do it? Start inhibit? or is there another system? Wouldnt the start inhibit merely cut the spark? The fuel pump should still kick in, and the CEL should still come on. The problem has to be in a loose wire/bad ground. I have spoken with quite a few Porsche mechs... Dean McCrarys, EuroCars of Tallahassee, Gossett in Memphis, and even the Porsche Regional Service Manager for my area... after it ran for a few days, they all said that it is probably not a computer failure, since it runs fine sometimes. Every example i have seen of DME or Tip failure has resulted in a constant issue, not one that goes away for days at a time.

The DME is covered under the emissions warranty... but if it is not the DME, then I end up paying dealership labor and such, plus have paid for towing across the freakin state of florida... which i am not willing to do yet. Does anyone in the Florida Panhandle have a PST2???????? I will BBQ and buy the beer!

Brian

[JebLacey]

One other thing about the humm...

when i touch any portion of the metal parts of the motor with a mettalic object (such as a wrench or a flashlight), the pitch of the humm changes, like i am altering the electrical pulse/curcuit. Is this normal? It sounds almost like a computer processing data :) how wierd!

[JebLacey]

i have located the electronic humming sound... it seems to be coming from the Idle speed adjuster attached to the throttle body. Should this be humming LOUDLY while the key is turned to accessory? Also, just as a side note, when the car wont start (no CEL at accessory), the humming from the ISA is not present... ie, it is not getting any power.

Could the ISA, if it is bunk, be my problem? I think not, but worth asking... i have never heard the humming before, when the car was running well.