0 The ignition key in my Z8 has been sticking since I aquired the car. I posted about it back in July and the consensus was basically try some lubricant in the key barrel or save up for the inevitable flatbed to the dealer for an expensive part replacement. I don't know about you, but I get a little hesitant to drive a car when it's really a crap shoot on whether the car will start again. So I've been worrying about it. This is a bit of a long post, so to cut to the chase, it all seems to be working correctly now (no sticking key) and I'm not sure why.
In researching the problem of the sticking key, I found this TIS article which explains the the startup sequence:
https://www.newtis.info/tisv2/a/en/e...n-lock/X0VbKnJ
In short, as I understand it:
When a key is inserted, it is recognized at insertion and the steering lock is released at that point. You should hear a sound like closing the bolt on a rifle (thanks to Matt Carver at Peter Pan for that description). A signal is sent out on the K-bus to release the turn inhibitor on the key barrel. This was not happening on my car (no rifle bolt sound) - on my car the steering lock never engaged - steering was free to turn at all times, car locked or unlocked.
If the car is asleep or does not electronically recognize the key at insertion, key rotation is noticed by a Hall sensor as the key moves 10 degrees toward the accessory position. Key rotation is blocked at 10 degrees until a signal is received from the K-bus recognizing the key. Key rotation is blocked for 700ms waiting for a signal from the K-bus. This is what was happening with my car. This is what feels like the key is sticking. It's an error message to the user that there is a K-bus problem! To the user, it seems like wiggling the key moves it past the sticking point - but really the system is waiting 3/4 of a second for a signal.
After the 700ms time out, the rotation block on the key barrel is released and the car decides to trust the key. Otherwise the K-bus error/problem would immobilize the car.
Anyway, that is what causes the "sticking" key.
My car reliably worked this way for months. Turn the key halfway to accessory, pause for a count, and then continue. Worked every time. So what changed?
As I mentioned before, I don't really know. Here's my solution sequence - it is long, but it did work in my case:
- Start the car (turn key, pause, finish turning key)
- Back out of garage
- Wash car
- Pause and appreciate just how pretty a black Z8 is when clean
- Hop in the car to move back into garage
- Discover the key won't turn past 10 degrees. Stuck. Try multiple times. Sigh deeply. Enjoy multiple emotions - sadness that it's broken - gladness that it broke at home - relief that now it's broken it will have to go to the dealer for some resolution.
And of course, resignation - after discovering that you can't push the car on your own and will have to explain to your wife that she will have to assist with pushing the expensive paper weight into the garage.- Once your wife is in attendance and has finished laughing, try the key again. This time it will work as before - turn, stick, pause, and it turns to the On position. Before the car changes it's mind, startup and pull into the garage.
- Get the car settled, finish the door jams, etc.
- Try the key again - stuck. And the stuck condition continues. Pulling into the garage was the last gift from the automotive gods for that day.
- Now the car is dead in the water. Key won't turn past 10 degrees. What could have changed? No obvious water in the cabin, all electrics working normally. When the key turned to the sticking point, after the pause I'd hear tic tic tic. I assume that was the barrel lock trying to release. I couldn't think of anyway to help it release.
- I decided to check for blown fuses, specifically the ones involved in the steering lock and startup sequence. Maybe wash water shorted something. I check 16,17, and 27 in the passenger foot well. Removed those three to check, all looked good. No corrosion or obvious problems with the contacts. Retried the key, no change - stuck at the 10 degree point. Gave up at that point - or rather, retreated to consider my options.
- Next day, after remembering a post about this problem where disconnecting/reconnecting the battery would allow one startup, I returned to the problem. Tried the key before doing anything. Heard the rifle bolt sound for the first time ever. Key turned freely. And this situation has persisted for ten days.
So back to the TIS article - apparently whatever K-bus problem was afflicting the car magically resolved itself. The only thing I did was swing the fuse box down and look at a few fuses. And after a day long wait, not immediately, everything in the key startup sequence began to work as designed - which I had never experienced in my four months with the car. It's not a very satisfying solution at this point, but I'm still happy it's working!
BMWZ8.US
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