Alternator testing woes.....bit of a story.

[Dave M]

Due to chasing this ignition issue with no resolve (yet), I've begun to suspect my alternator. Please bear with me, there is a test (question) at the end.

Since yesterday, I've had my alternator (bosch unit from my M50) into 3 shops to have it tested.

The first joint brought it back to me and said:

"it doesn't work"

I say, "so......whats wrong with it, what was it putting out?"

Them, "I don't know, I didn't do the test" (this is the owner speaking, by the way, great customer service)

I say, "can you do some investigation and let me know whats wrong with it"

I call back later and he tells me theres a part broken, he may not be able to get it, BUT, he won't tell me what the part is. He sais, "why would you want to know that". I dunno, just to piss you off? Hence, I assume he's trying to fleece me and I leave him with a bewildered look.

Shop #two brings it back and states its "intermitent" and "we wouldn't fix it, we'de sell you a new one". I don't ask details as I'm running late, but do inquire, for fun, what a new one would cost. Answer $575 .

So, later in the day I hit up little hole in the wall place and am greated by a friendly young man who helps me out. He tests it immediately and states it seems fine. I tell him the story of the other two places and he agrees it sounds fishy in the least. I ask him to take a better look at it and that I'll pay him for his time. He declines $$, looks at it, calls me back and states he can't find anything wrong.

So, WTF? As my ignition cuts out at low rpms, I asked him to try and turn it as slowly as possible to see if it fails. Maybe the other places were turning it slowly? Haven't heard back yet, but I thought it was an interesting morning and wanted to share. Oh, if it checks out OK, am I out of line to ask either of the other two places to show me the test? I wonder if they'd both decline.

F'ck, I wish it was as simple as a bum alt. End of semi-rant. Still optomistic,

Dave M

[632 Regal]

I still think its something to do with the alt or regulater, hope you figure this thing out soon.

[ryan roopnarine]

dave, take the access panel off of it and see if the voltage regulator i sent you will look like it will fit. from your pics, it looks like you have the utilitarian 100 amp model (the regulator i sent you from mine is 140a unit), but if the board says it can work, you are certainly welcome to put it in...i guess you'd have to get the brush soldered in there first. i personally don't think that you have an electrical problem, as my FPR has started acting up in the cold for some reason, but, as i hopefully implied, i sent the thing to you with the hopes that you can get some utility out of it.

[pingu]

Can you temporarily wire in a multimeter so that you can always keep an eye on the voltage at the B+ terminal (don't trust the OBD #9, it's not so accurate as a DMM) when your ignition next cuts out?

In any case, presumably your battery isn't too good as even if the alternator is intermittent, I'd expect the battery to be able to power the car.

Did you see that post a couple of days ago by shogun that required registering at a 7 series form? They described a case situation where the B+ connector itself was faulty which had the effect that the alternator wasn't always properly connected to the battery and ignition system - or something like that!

[Dave M]

Well, I was able to watch the last alt test and I am now convinced its NOT an issue. The last guy took it apart, spent some time and said its fine. He was a bit ticked the competition was, seemingly, less than honest. Ryan, I do have a 140 amp Bosch unit, but the regulator you sent won't fit (my brushes are > 5mm). Anyhow, I just finished re-installing it and doing another load test with it in the car. At idle the batt is kicking out ~14, when loaded with everything electrical I can throw at it, it dips to a low 11.7-12 at idle and back up to 12.5+ at 2000 rpm (OK by bentley). It stuttered once while I was looking at the multimeter and it seemed as though the temporary, subtle drop in voltage was more of a symptom than a cause.

I received a coolant temp sensor today, swapped it in and it still missed a couple of times . The f'ers at Winnipeg bmw dealership didn't pack the dme and fuel pressure relays so i get to wait a while longer. Good news is, Shawn's check valve arrived, so it will be sent to GB ASAP.

Question: when I was messing around with the coolant temp sensor and engine temp sensor, I recalled being a bit befuddled when re-assembling my engine last winter. I failed to mark which connector went to which sensor and took my best guess based on bends in the wiring. If I got it wrong, might it cause this problem? Hmmmm, I swapped the connectors and the car ran fine (the temp gauge showing a bit hotter), but I'll have to wait for another cold start to find out more.

Anyhow, Jeff, i'm not too concerned as its no longer a needed vehicle. I'm more annoyed that the first two alt shops I wasted my time at may have been trying to fleece me

I'll be back

[Dave M]

In any case, presumably your battery isn't too good as even if the alternator is intermittent, I'd expect the battery to be able to power the car.

Well the batt passes all the tests so I assume its good and a sign that something else is up if it still hiccups. Another reason i'm leaning < back < toward sensors, relays, wiring and gasp DME.

[BillionPa]

on my car when i started messing around with stuff.... i found that the remote battery terminal in the engine bay had about 3 wires feeding into it that were held in place by a screw, and oh boy that screw was loose! check there.

[Dave M]

on my car when i started messing around with stuff.... i found that the remote battery terminal in the engine bay had about 3 wires feeding into it that were held in place by a screw, and oh boy that screw was loose! check there.

Fortunately, my batt is located in the engine bay, so no extra wiring. I'm not ruling out a loose connection, but I'm pretty sure my batt connections are OK. In fact, I scrubbed everything down again last night when i replaced my alt.

Thanks,

Dave M