SOLVED (hopefully) - Ran the same test: Turned on the ignition with only the DME and water pump connected, and then connected each of the other components separately (IBS, alternator, oil sensor), and when the oil sensor was plugged in the water pump started (I believe in effect sending a signal to the DME that causes a loss in connection between the DME and the water pump). I plugged in all components except the oil sensor and to my surprise I was even able to clear all the codes without the BSD error reappearing (I figured if one of the BSD components was disconnected I'd still get the error). So I guess I'll be ordering a new oil condition sensor and some oil since all the oil will need to be drained. I may not rush to do that since my oil was changed recently and I don't really need the oil sensor operational right away.

What's odd is that component appeared to be working fine, measuring correct oil level etc. Or at least I hope it's measuring correct oil level... maybe I do need a new one right away. Also, I'd tested disconnecting various BSD components in the beginning and still had the fault. I still suspect something was off with the alternator/voltage regulator as the symptoms were much less severe after replacing that. I also have some suspicion that the DME might have been confused and hooking up the battery with just the DME and the water pump may have helped - pure speculation on that though. I suppose re-cleaning the water pump connector may have helped, and possibly also getting a proper fit on one of the ignition coil ground wires. As always, there could have been a combination of problems, but it's still strange that all this started after changing the starter, a coil, and a new valve cover gasket - all of which seem unconnected to the BSD system!

Anyway, a sincere thank you to all those that contributed, particularly scottalexander - much appreciated! And thanks for your encouragement on the clean engine I will work on the sensitive areas, but with 175K miles I can't promise perfection. And I won't be sharing any pics of the underside of the car

 

NOT SOLVED!!!!

So I got the new oil sensor and installed it. Plugged it in - water pump doesn't run - looking good. Turn on the car and it runs rough and dies Unplug it and it still runs rough and dies. Plug it back in and unplug the water pump, and it runs perfectly. Plug the water pump in while it's running and it dies. This is driving me nuts! No engine error codes at all now! The car might just be possessed.

 

If I had to bet the farm on what's wrong, I'd vote for a bad water pump (again). Are you still getting the original error code? If so, I'd try unplugging everything on that buss one item at a time, and re-firing the car to see which one is triggering the code. Sure SOUNDS like it would be the water pump. There could be some sort of low-impedance "short" in the water pump wiring (from that oil leak?) that could be causing some odd current path across the wiring that doesn't happen when the pump is unplugged.

 

Thanks habbyguy. To clarify, I'm not getting any error codes now, which seems strange. It certainly could be the water pump, or something on the system that acts up when the water pump is plugged in.

Today I decided to go back to my last test state (pre- oil sensor replacement). Even though I now have no codes, the symptoms haven't changed much, so I'm thinking it still has to do with the BSD system. I unplugged all the BSD components except the water pump and DME, turned on the ignition to make sure the pump isn't running (it's not), plugged in the oil sensor and it doesn't start running. I'm thinking this is good since it establishes that maybe there was a problem with the old oil sensor. Anyway, I unplug the oil sensor so just the water pump is plugged into the DME, and then start the car - runs perfectly. So I plug in the oil sensor, still working, plug in the alternator, still working, lastly I plug in the IBS and the car stalls - red flag. I try a few other combinations like unplugging the alternator and plugging in the IBS in case there's an interaction that's not good, but it seems like the IBS is the root of the problem now (the IBS that I've already replaced once). I figure at least I can drive the car without the IBS even if I don't take this hunt any further. On a wild hunch, I check the recent battery registration I did when I replaced the battery, but the DME isn't showing it, so I re-register the new battery - could this be part of the problem? (I have to turn off the engine and plug in the IBS BSD line to register the battery). I restart it with everything hooked up and it seems to run fine. Of course it's fully warmed up now, which is when historically the symptoms disappear. Since it's running well and my rear tire is losing air after all this time, I pull it off the jack stands and drive down to the local gas station to pump it up. All goes well on the drive, but when I'm sitting in my driveway resetting the clock/date, the car dies again. Everything points to the IBS. Will try again tomorrow with a cold engine.

I'm thinking it's possible the new IBS I received was damaged when I got it - I've heard they're fragile. Plus, my voltage stays the same whether the IBS BSD line is plugged in or not, or whether the alternator BSD line is plugged in or not. I believe it's supposed to be different. I don't think there's any way of testing an IBS though. Reluctant to buy a new one just to test the theory. Regardless it seems like I must have had failures in multiple components to get all the symptoms I've had to work through. I suspect the IBS, the alternator/voltage regulator, and the oil sensor all had some sort of issue, and the battery was probably weak. I suspect the water pump/thermostat, and the starter might have been fine, and not needed replacing.

 

When in doubt how things work, it's always good to reference the Bentley Manual:

https://www.newtis.info/tisv2/a/en/...sv2/a/en/e60-550i-lim_200611/wiring-functional-info/body/voltage-supply/XlIbeSm

 

It would appear that ISTA-D has a mechanism to test the IBS.

Take a look at the attached picture and the red arrow I drew to the IBS section.

Go through the exercise and test the IBS in ISTA-D.

Next:

The IBS has a temperature sensor in it. You keep talking about how your car only runs well when its at operating temp.

Perspective:

Ok, you replaced a bunch of parts that are known faults on these vehicles and you have received all the personal intrinsic benefits of doing the work yourself. That's a nice benefit.

You've got a bunch of new parts in the car and it should run well for a long time.

 

@alphaphoenix - thanks for the link. It's helpful to understand the IBS a little more. I also noted that at one point it said "vehicles without intelligent alternator control", which leads me to believe that not all vehicles will change the alternator output depending on what the IBS says. I'll have to look into that further.

@scottalexander - thanks for the perspective - words of wisdom. I still have to get the ISTA-D package. I downloaded the standard package but am having some computer glitches... will continue down the path regardless because I want to get that set up, but for now I'm still working with my Foxwell scanner. I have limited testing time today but I wanted to do some basic tests while the car was cold.

I attempted to start the car twice with everything plugged in and it didn't start. So I unplugged the IBS and it started right up. This seems to enforce the previous theory, but after about 30 seconds it dies. So I try the reverse - plug in the IBS and unplug the water pump - it starts right up and seems to run well for a while (I don't want the car to warm up so I didn't test it too long). So I unplug the IBS then plug in the water pump again and stays running. Then I plug in the IBS and it dies immediately. Bottom line, something is off when both the IBS and the water pump are plugged in, and it seems from limited testing that the IBS is impacting the situation the most. Of course habbyguy could be right too - maybe I have another bad water pump. Since the temperature of the engine seems to have a big impact on the problem, I can't let the engine warm up too much, so my testing window is limited.

My other vehicle is a 2007 X5 and it occurs to me that the IBS is probably the same. I forgot that when I first suspected the IBS was a problem (close to the beginning of all these issues) I checked and they were different, BUT when I went to order a new IBS for the 525i it turns out BMW has stopped making that part so I had to buy the new "recommended part" along with two adapter cables (this makes me wary). Still, I bet with the adapter cables I can switch the 525i IBS and the X5 IBS and see what happens. I could even try the old IBS in case that wasn't really a problem after all. Looking at that now.

 

Quick update on the IBS swapping. I swapped out the new IBS with the old IBS and everything seems about the same. This doesn't solve much because I still don't know if they're both good or both bad. I was hoping to use the IBS off the X5 to see if I got a different result, to confirm either 3 good IBS's or 2 bad one's and one good one, but even with the adapter connectors I bought, the X5 plug is slightly different and it looks pinned out differently (if I go by wire color). Looks like that test might be a dead end.

With the IBS disconnected again, it started fine, then died after 30 seconds. I restarted it and it's been running fine for 15 minutes or so. It's almost normal/driveable at this point if I just leave the IBS disconnected. Still, I'd love to get this resolved properly.

One interesting tid bit - I ran some tests on the X5 and also didn't get much of a change in voltage when connecting/disconnecting the IBS BSD cable. One interesting difference was that I got an error code with the BSD cable disconnected that I don't get with the 525i - a 2EDE error (DME: Power management closed-circuit current violation). The X5 is the same 3.0 engine and the same year, but it could be running different software. Probably nothing, but figured I'd mention it.

 

I'm in a position to make you an offer.

First, a little context before the offer.

I was working with a guy on this forum many months ago. His battery was going dead because the water pump was running continuously. After the car was shut down the water pump would still run and kill the battery.

What he would do is unplug the water pump at night and then the battery had enough energy in the morning to start the car.

Now he discounted the water pump was bad because it was only 2 years old and didn't have many miles on it. What he did was buy a new water pump. Before he installed it, he connected the new water pump up to the electrical harness and much to his amazement the water pump didn't turn on. Good news. He knew that if he installed the new pump it was going to function properly.

Here's the offer:

We can run a similar test at a low cost.

I have a water pump with 45,000 miles on it sitting on my shelf. I can give it to you for free. The cost to you is shipping cost from Philadelphia to where ever you are.

Why do I have this water pump?

I wish I had a dime for everyone on this forum who's water pump died. I wanted to avoid that event. Being paranoid, last year when my car hit 45,000 miles I proactively swapped it out for a new one.

Some say the circuitry in these water pumps overheats and the board cooks so the pump fails. Another hypothesis is the water pump being covered with oil doesn't help and the oil makes its way to the electronics. Also, many don't change their Pentofrost NF and claim that doesn't effect pump operation.

 

Thank you - I really appreciate that. To clarify though, the water pump is no longer going on when I plug it in (that was the case in many of my previous test scenarios, but after replacing the oil sensor that doesn't happen at all). If I plugged in a new correctly working water pump then it also wouldn't (and shouldn't) turn on just like the one I have now. I suppose if I plugged it in with the IBS plugged in and the car started fine that would say a lot. I probably should try plugging in my old water pump in first and seeing if that makes a difference (in case the new water pump is bad and the old one wasn't). Of course they could both be good or both be bad, just like my recent IBS swapping test. What are your thoughts?

 

Good thinking.

Run an exercise and plug in the old water pump and see what happens.

 

OK, so I plugged in the old water pump with everything connected and the car didn't start (and the pump didn't run). Then I unplugged the IBS and the car started but ran pretty rough - much rougher than the day before. So I unplugged the old water pump and plugged in the new water pump and it was still running really rough. It was colder and rainy, so that could have been why. I also thought maybe there was oil contamination on the plug from the old water pump, so I thoroughly cleaned everything with the electronics cleaner, let it dry (I thought), but now it won't plug back in. Feels a little spongy at the end where the clip would normally snap into place, so maybe I over doused it and whatever gasket is in there swelled up. Everything looks squeaky clean, but I can't get a super close look because the car's on the ground. Hoping everything will snap back together once it fully dries out, otherwise I'll put it back on the stands and inspect closer (the plug is just a tangent I realize). Bottom line, it appears to act the same with both pumps. I expect both pumps are good. It seems unlikely that many new OEM pumps come off the line not working... has to be like a 0.1% thing I would think.

 

BTW, I did also test it with both the water pump and the IBS unplugged and it ran perfectly... makes no sense (to me anyway). The difference between how it runs cold and warm is a head scratcher too.

 

New Idea:

You are not the first person in BMW history with this problem. While we can't find the solution in the BMW forums, we might be able to find the problem in other forums (e.g. Mercedes).

Next:

Its time to call Pierburg and Continental who makes these water pumps. Which pump do you have?

The Pierburg product managers who work with their knowledge management data base each day know what is happening with your water pump. They can crack this mystery in two seconds.

There was a guy recently on this forum with a transmission problem. His mechanic did a bunch of replacements and it never fixed the problem. The mechanic finally called ZF and they told him the solution. It was a bushing.

Its time for Pierburg to tell us the solution.

 

Good suggestion - thanks. I have the Pierburg pump.

Another thought... not to confuse hot/cold vs moisture, but I recall many, many years ago having misfire problems with my old car whenever it rained. It turned out the spark plug wires were bad/old. Could the temperature/weather affect the wiring somewhere here to make the fault mostly disappear as the temperature goes up and humidity go down? BTW, still no error codes except the scan tool recognizes when certain components are unplugged from the BSD system.

 

Good point. There could be wiring faults or a water pump harness connector fault.

Next:

You have a Foxwell scan tool and all the BMW forum guys love the model 510.

However, we are at the point were we can't rule out the following.

If we connected ISTA to your car, would ISTA capture a fault code that Foxwell isn't identifying?

We have to run the exercise with ISTA because it might give us a aaahaa moment. Or it might not produce anything new, but worth a try.

I live and die by ISTA and work on the premise if ISTA can't identify a fault, nothing can.

 

Thanks. I'll work on the ISTA install. I'm sure i need to buy a cable too. I want to back up my computer first since I was having some issues... I'll get there!

I did send Pierburg an email - might be a bit of a long shot that they'll respond to an end user, but you never know.

 

Similar story:

I reached out to Valeo in France last year (the firm that makes my alternator).

The reason I did this is because I wanted to buy a voltage regulator for $30 and everyone wanted to sell me a new alternator for $400. Many places had Bosch voltage regulators, but not Valeo.

I did some research and found the name of the product manager for Valeo alternators. I didn't tell him I was a retail customer.

It took 3 weeks and he told me two firms that will sell me the Valeo voltage regulator.

Better late than never and it was a 5 minute job putting in the new regulator.

We need to find the right guy at Pierburg and he'll help us.

Its going to be funny if we find out Pierburg gets this question 20 times a day.

 

Thanks once again for the feedback.

I have a new idea I wanted to float out there (to see if it's crazy or not). The starter has two connections - the main power connection and a secondary connection, which I assumed was to activate a solenoid to engage/disengage the starter with the flywheel. Is it possible it does more than that? Presumably a lot of power is coming from the battery and that gets switched off or redirected at some point and the alternator kicks in to provide power to the battery.

Background - I was keeping the engine revved up today while the monitoring the engine cutouts (it was almost shutting off but keeping running) and I noticed a consistent drop in voltage each time the engine almost shut off (the battery was also low so that may have contributed to the drops). Anyway, it lead me to thinking that the ignition (spark plugs) may be getting most of their power directly from the alternator rather than the battery, and if the alternator shuts off suddenly and temporarily, maybe it switches to the battery, and then back to the alternator causing the shut off. Question - is there something in that connection to the starter that controls power distribution, and if that connection was bad, could it cause power interruptions from the alternator? It seems a bit left field, but if the starter connection were messing with the alternator, perhaps the alternator could have been messing with other components on the BSD system. Again, I don't have a good enough understanding of the interactions. Might be a crazy idea but it would line up perfectly with the starter replacement being the root cause. Of course to get to the connector, I'd need to take out the intake manifold, so it's not an easy test. Crazy idea or not crazy idea?

 

Quick note - I sent an email to Pierburg/Rheinmetall and a Service Engineer from Dormagen, Germany is helping with the problem! I've shared some more details with him so hopefully he'll have some insights. I'm impressed that they responded. Usually companies only deal with their direct Manufacturers or Distributors. Thumbs up for Pierburg!

 

Whoa... that's odd. Depending on the actual voltages you're measuring, that is.

It would be potentially normal for the voltage to sag a little if the engine speed was reduced to below idle speed, if the battery isn't fully charged, at least. But if you're seeing the "battery voltage" dropping below 12 volts with the car running, it COULD be causing your other maladies. All those electronics get really fussy when you take away their nice, clean 12-14 volts!

What is the "normal" voltage, and what is it dropping to when the engine stumbles?

 

The normal running voltage seems to be about 13.7 volts, and when it drops it drops into the 12's. Not a huge drop, but keep in mind I'm getting my readings from the scan tool that's talking to the DME. I don't know where the original reading comes from. I'd guess from the IBS, but when the IBS is unplugged I still get a voltage reading, so who knows. There seems to be a delay in the reading though so I'm thinking it could actually be dropping below 12 volts, but since the drop is for such a short period it never registers that low because the power comes right back on. While it makes sense that a sudden drop in voltage could cause a whole bunch of other problems, why would the drop not happen when the water pump and IBS are disconnected...

 

Nice to hear Pierburg is helping with the problem.

With thousands of people ob BimmerFest.com its a good idea for them to weigh in.

At some point Pierburg will tell us what they believe the problem is likely to be


Let's have some fun and make a few predictions when Pierburg comes back to you. They will say:

a) your problem is very sophisticated and we are working with Steven Hawking's younger brother to diagnose the issue

b) your BMW has coronavirus we are working with the Wuhan team. I hope we can get it fixed while you are still young

c) this issue is cake and my grandmother has been assigned to contact you shortly with the resolution

d) ?

 

Haha! Nice

 

You are not going to believe this. I think the problem is solved!

As I've been contemplating voltage drops, that nagging theory about bad coils was bouncing around in my head (mentioned in post #42). Just like the starter cable connection theory, I didn't like it because even if it were a bad ignition coil causing all sorts of problems it makes no sense that unplugging the IBS and water pump would stop the problems from happening. The voltage issues would still exist regardless of what was plugged in. Still, it was bugging me, and I figured it was an easier test than getting to the starter connections. While it seemed like a long shot, since I had a spare ignition coil, I replaced each coil one by one, and started the engine, experiencing the rough running each time. On the fourth coil, I noticed the coil I pulled out had a broken ground pin.* Replaced it with the extra coil, started the car and now the car seems to run perfectly even with the water pump and IBS plugged in.* I'll test it again tomorrow when the engine is cold.*

This makes no sense to me.* It's also amazes me that a car can have a bad ignition coil causing all sorts of voltage and engine cut-offs and throw zero codes. If anyone has any insight how unplugging a water pump and IBS from the system can alleviate the engine cut off symptoms, stemming from a bad ground on an ignition coil, I'd love to hear the theory.* I'm glad it appears to be working now.* By the way, here's the link and explanation from the referenced post in case it helps anyone figure this out.

Link
Explanation:
Root cause:
Aftermarket Delphi coils sending voltage spikes back through the "ignition" circuit due to insufficient insulation.
Side effects:
BSD codes, alternator damaged by the coil voltage spikes, causing the alternator to send its own voltage spikes through the charging circuit
Diagnostic path and fix:
1) Replaced alternator after observing it spiking voltage on charging circuit; new alternator does not spike voltage, but BSD codes still present (and related drop to battery voltage when present)
2) So tested other components on BSD line - all good; then tested ignition circuit and observed a separate voltage spike on that circuit coming from the coils (not a misfire in combustion chamber, so no misfire codes). Replaced coils with genuine OEM coils and these voltage spikes disappeared.**

Anyway, thanks again for all the help and suggestions. It's truly appreciated! Hopefully all your insights help many others. Feeling humbled by how much I still have to learn, but in the mean time I'll be driving around