Loud explosion inside cabin Z4M

[Punisher3.0si]

Originally Posted by The HACK

Have you tried jump starting the car? Car should still run without the battery.

Modules don't like large voltage spikes. I've seen them let the ghost out doing that.

[RossBMWZseries]

My car doesn’t start or crank at all. There’s a clicking noise at the starter. I ordered the BST but no one seems to have it in stock locally or online. I’m having it shipped overnight once they have it in stock so hopefully I can get it before the weekend to install it. I have my starter ready to go so I guess it’s time to replace it as well. Will update once both have been replaced.

[Vanne]

My mate has bypassed the BST since last year, no issues. It too went pop withany anything going on.. was weird. hasn't had any issues since.
your mileage may vary though..

I wonder if its related to all the electrical gremlins you've had?

[RossBMWZseries]

I’ve wondered the same thing Vanne, aferall the electrical issues I have typically only happen when the air bag is lit on the dash. Once I replace the BST, I’ll clear the airbag code and observe if any changes happen with these gremlins. If that’s the case, i may save myself money on buying the SAS and clockspring. Currently waiting for my code scanner to arrive as well

[dc_wright]

Originally Posted by RossBMWZseries

I’ve wondered the same thing Vanne, aferall the electrical issues I have typically only happen when the air bag is lit on the dash. Once I replace the BST, I’ll clear the airbag code and observe if any changes happen with these gremlins. If that’s the case, i may save myself money on buying the SAS and clockspring. Currently waiting for my code scanner to arrive as well

In the BST assembly the plug on the end of the heavy cable is pushed into a socket. It's a press fit so that the explosive can blow it out and break the connection. I'm guessing that the connection there got some corrosion or something that increased the resistance of the connection. That created a hot spot which got hot enough to set off the explosive. The explosive compound is a bit heat sensitive and I set mine off cutting it open to see what was in the BST. If my theory is correct then you had an intermittent connection for your main power and that could cause some very unhappy electronics.

[Vanne]

DC, hmm, I hope so, but I was under the impression that that thick lead was for starting only, car will still run without the BST connected, just wont start.

at any rate, I hope things become clearer when we find out if the car is throwing any codes. Id take my hat off to you Ross, Having a car that's unreliable is the pits, regardless what make it is.

[StickMon]

I think dc is on to something.
Hopefully the intermittent connection was the source of all the meshugas Ross has been having.

[SaltyNC]

Originally Posted by dc_wright

The explosive compound is a bit heat sensitive and I set mine off cutting it open to see what was in the BST.

I bet that got that heart pumping.

[Huz-Z]

Recognizing that there are a great many folks on this forum who are incredibly talented with taking these cars apart and quickly and effectively finding and fixing issues - like I am totally in awe of them - and in view of the fact that this car has been driving our good buddy Ross for quite a while now and it really should be the other way around - would it be a fair idea to take the car to a decent local dealer (assuming such exists nearby, or am I delusional?) and asking them for a no obligations quote on what may be going on?

I'd just like you to have absolute certainty that the car is sorted in all respects, leaving nothing unaddressed, so that when you take her out for a spin, your only worry is sticking to the speed limit.

[RossBMWZseries]

What DC is indicating makes sense, I hope that turns out to be the case.

Huz-Z; Lol good one. I would do that if I could trust my local dealer or even my go-to guy with this type of issue, but I don't. I rely more on the knowledge of these helpful forum members and my ability to DIY it myself. I ensure I do it 100% correct, if not that's when I seek other help.

[GuidoK]

So are you going to delete the BST and bypass/fool the ecu or are you going to replace the BST?
It's after all quite an important safety feature.

[dc_wright]

Originally Posted by Vanne

DC, hmm, I hope so, but I was under the impression that that thick lead was for starting only, car will still run without the BST connected, just wont start.

at any rate, I hope things become clearer when we find out if the car is throwing any codes. Id take my hat off to you Ross, Having a car that's unreliable is the pits, regardless what make it is.

Correct, but having the battery connect and disconnect can still put some spikes on the 12V power.

[RossBMWZseries]

I’m not bypassing the BST GuidoK, too important of a feature to bypass like you stated. I have the new BST in hand now. I removed the battery and the housing that holds it. There’s a lot of dirt back here. When I crashed about 3 years ago I was hit exactly in this spot (rear quarter panel). Perhaps the BST was just triggered now as it wasn’t triggered years ago, highly doubt it though. My passenger tail light had a crack done by my local dealer, they refused to replace it. Through that crack, water and dirt came in. I’m guessing the connectors are dirty as previous members have indicated. I’m removing and cleaning EVERY cable I can remove and then putting in the new BST.

[RossBMWZseries]

Anyone know how to remove the BST red cable that runs down to the floor of the car?

[RossBMWZseries]

So I’m done cleaning and dusting all sensors and cables off. I can not remove the BST cable, the part that connects to the floor. I have unscrewed it from the cable itself and it keep rotating counterclockwise but it just won’t come off. Seems like it’s a bit loose now but that’s all it’s doing. I don’t have to crawl under the car and somehow unattach it right?

[GuidoK]

according to TIS you have to dismantle quite a lot under the car to completely replace that plus cable. Its quite a job by the looks of it.

Isnt it possible to put the pin back in the bst and drive around for a while with the new bst connected? From what I can see you havent 100% located the cause why it went off.
So maybe test it for a while?

[RossBMWZseries]

Originally Posted by GuidoK

according to TIS you have to dismantle quite a lot under the car to completely replace that plus cable. Its quite a job by the looks of it.

Isnt it possible to put the pin back in the bst and drive around for a while with the new bst connected? From what I can see you havent 100% located the cause why it went off.
So maybe test it for a while?

By any chance Do you have a link to this TIS? I’d like to dismantle and put everything back today if possible.

You’re right, I still don’t know the reason as to why it blew up. I’m not sure how I would figure this out so I rather just get it back to how it should be.

[GuidoK]

I think you need this one:
https://www.newtis.info/tisv2/a/en/e...-cable/ILOsAx4

I didnt realize that the main + cable was in 2 parts, apparantly the bst is just a short piece with the z4m (for the normal z4 you have to replace the cable all the way up to the engine bay)

[RossBMWZseries]

Originally Posted by GuidoK

I think you need this one:
https://www.newtis.info/tisv2/a/en/e...-cable/ILOsAx4

I didnt realize that the main + cable was in 2 parts, apparantly the bst is just a short piece with the z4m (for the normal z4 you have to replace the cable all the way up to the engine bay)

Yes sir it’s more of a PITA for the non M. Those intrauctions are it! Let me give it a go, thanks for the help GuidoK!

[3798j]

Originally Posted by RossBMWZseries

Yes sir it’s more of a PITA for the non M.

If I had to replace one (non M), think I'd try splicing in the new BST using an insulated cable splice like this...

[RossBMWZseries]

So I cleaned everything, replaced the BST from under the car by placing the rear tires on the ramps. I started by following the TIS provided by guidok. I removed the carbon canister and right tension strut, THAT IS ALL. I didn’t remove the muffler/X-pipe, right output shaft from the differential, or the stabilizer bar. I was able to squeeze my right hand right next to the differential and kind of did most of the work with my right hand and one finger from my left hand. The rubber boot under the BST holds a nut where the BST screws into. That rubber boot has a cap, just had to be pried off.

As I’m placing everything back, I accidentally over tightened and broke a small screw on piece #4 shown on the diagram above. It’s a built in screw that faces up, and is tightened by a nut. The whole piece is about $30 according to realoem, but I don’t wanna wait for shipping and I doubt the dealer has this part in stock. Is there any other simple solution to this? Providing pics below showing all the dust collected, also showing where I was able to access the underside of the BST, and the screw I broke

[RossBMWZseries]

I hope pictures are clear enough