deane.barker

I posted about this saga previously here: 1999 996 Carerra delayed start...then no start

There was an ever-increasing delay in (1) turning the key, and (2) the car actually starting. I'd turn the key, and the car would...wait, for 3-4 seconds, then start and run normally.

Then, one day, it didn't start at all.

I don't have a local dealer, so I had to have the car flatbedded to Omaha, where they worked on it for two weeks. They diagnosed it as a bad ignition module, replaced that for $900, and I drove down and got the car back.

The problem has now returned. There was a small delay when starting a couple days ago, then it got longer, and longer, and then this morning, I got it on video:

https://www.dropbox.com/s/nmit8ul2rp...47.19.mp4?dl=0

(Dropbox link. It should open in their player.)

This only happens when the car is cold (it's not bad in Sioux Falls right now -- low 30s this morning). I suspect the car won't start tomorrow.

I have emailed the Omaha dealer. I'll update this thread when I hear from them.

MikeinBloomfield

You replaced the ignition module because it wouldn't read the chip in the key, but did you replace the key? I am relatively new to these cars, but this seems to be an "authorization" issue, rather than a mechanical one. What I mean by that is once the car decides to start, it seems to work as advertised. The car seems to be waiting for authorization to do so. And some of that authorization lives in the transponder in the key. Just seems that way to me. I understand the dealer is far, so trying a new key may not be easy. Is the transponder "generic" or keyed to individual cars?

Ahsai

I agree with this advice. Any chance you can use another key (that has another transponder). Authenticating a transponder only takes hundreds of milliseconds but if it fails intermittently, the retries may take more time. It's quite plausible.

deane.barker

But what do you make of this -- the problem only happens when the engine is cold.

I just started it again, after it sat for three hours in 30-ish temps. It was bad. A 6-7 second delay (it's clearly getting worse by the hour).

I then shut it off and turned the key again...and it started immediately. No delay at all.

MikeinBloomfield

The only thing I can think is that maybe the transponder check has a time out you haven't reached. So if you try and start it having just shut it off, the car doesn't need to check with the transponder. Unlikely, I admit. Or whatever is affecting your transponder reacts to time or temperature.

In any case, if the transponder isn't individually specific, you could hold another 996 key near the ignition when you try and start it and see if that changes anything. The transponder is probably car specific so this would probably not work, but its just a thought before you drive all the way to the dealer.

Ahsai

...

Ahsai

Just wire a 12v light bulb to the starter relay and see if it lights up during that delay. If it does, good news. It's likely your starter. If not, it's likely the key/immobilizer.

rb101

Ok, my quick quess is the starter solenoid is sticking. There is power at the starter all the time via the heavy cable from the battery. The immobilizer allows current to the solenoid (small wire) when the key is turned and approved. The solenoid moves the bendix into the flywheel and makes the connection between the battery cable and the actual starter motor. The solenoid is gummed up and slowly moves the bendix/makes motor connection, this is worst when its cold.

Ahsai

^ Exactly. Just wire a 12v small light bulb (where you can see it when cranking) between pin 87 of the start lock relay and the ground.

https://rennlist.com/forums/996-foru...l#post12188715

speed rII

And after you test that there is no 12v on starter solenoid, clean the immobilizer ecu.

deane.barker

First of all, I didn't get notifications of the above responses, so I haven't tried any of that. Thank you guys for all the advice.

However, I do have a very weird clue. Stick with me, because this is gonna seem a little strange --

First of all, the problem has been infuriatingly random. It comes and goes. There's no rhyme or reason to it at all, which drives me nuts because I can't just drive it three hours to the dealer and hope it happens while it's there.

But, tonight after work, I turned the key...nothing. I turned it back, then tried again...nothing. I took out my spare key (I'm still testing the bad key theory) and tried that...nothing. Then, I tried one more time...and it started normally. So, it started on the fourth attempt.

And this is where it gets weird, because, sitting there in my now-running car, I realized something: I knew it wasn't going to start when it didn't start, and the last time when I tried it, I knew it WAS going to start. I'm very serious. I just...knew at some level, right before I finished turning the key to ignition, when it was going to start, and when it wasn't going to start.

What this means is this: there's a "tell." There's some kind of clue right before ignition that subconsciously tells me that the car is going to start or not start. Forgive the comparison, but I'm reminded of the "aura" that epileptics feel just before a seizure. They know they're about to have a seizure, but they can't tell you why they know, they just do.

When I got home, I sat in the garage and turned the key to the "ready" position a couple of times (so, to the position just before the final turn when it starts -- I don't know what this is called). The car makes a bunch of sounds when you turn the key to here -- a bunch of dash lights go on, and there's some clicking and whirring from under the dash or perhaps from around the battery compartment. It all happens within a second or two.

One of these things does not happen when the car isn't going to start. I can't tell you which one, but I swear, one (or more, I guess) of these sounds doesn't occur, so I can just subconsciously sense when the car isn't going to start. Then, the final time I tried it tonight, that sound did happen, and that's how I "just knew" the car was going to start.

I swear I'm not crazy. Does this make sense?

(I told you this was weird.)

What's great is that now I have something to listen for. Whenever I start it now, I'll pay very close attention to the sounds, and with any luck, it will happen again and perhaps I can isolate the sound that missing from the no start situations. Stay tuned.

Woodman71

Stranger things!

Ahsai

I think if the immobilizer can't detect a valid transponder, it's not going to activate the fuel pump. I'm not sure if this is true even for the normal 1s priming you hear at the last position before cranking. If it does, that could explain what you are experiencing and it also points to an immobilizer issue. BTW, have you changed out the ignition switch?

deane.barker

This is what was on the paperwork from the dealer after I got the car back:
I am beginning to think that this was not the problem, and the sporadic nature of it just cleared up while the car was at the dealer.

deane.barker

Here's some more stuff from the dealer paperwork:

FAULT CODES 23 W LINE SHOT TO B ANS 25 TERMINAL
86 S NOT DETECTED STORED IN THE ALARM SYSTEM
CONTROL UNIT. VEHICLE KEY UNIT IS FUNCTIONING
AT THIS TIME. VERIFIED FUSE 1 CHECKS OKAY. FOUND
LOW VOLTAGE READING AT FUSE 5-6 VOLTS. VERFIED
WIRING BETWEEN FUSE AND IGNITION HOUSING IS OKAY.
IGNITION HOUSING ASSEMBLY IS FAULTY AND WILL NEED
REPLACEMENT.