Please help!

So my 1995 525i recently had a succession of issues and i am hoping someone may have some insight. First, my rpm gauge and mpg gauge, would start randomly going dead on me. Simultaneously the brake fluid light would come on. At first i thought maybe it was just a short in the cluster because the car ran fine and the problem was sporadic. The problem steadily increased, and then probably about a week later "bing" the trans program light comes on. I could shut the car down and restart it and it would go away and drive fine for about 5 minutes before it would come back on. I let the car sit for a couple days and noticed it was running rough when i started it until it warmed up. I have topped off tranny fluid and no change. Any ideas? Thank you!

As odd as it may sound, I recommend that you have the alternator checked. Your symptoms seem electrical in nature and I have seen others who got the dreaded trans program error and the fault was the result of a bad alternator.

Hope this helps.

Originally Posted by BMR_LVR

As odd as it may sound, I recommend that you have the alternator checked. Your symptoms seem electrical in nature and I have seen others who got the dreaded trans program error and the fault was the result of a bad alternator.

Hope this helps.

+1

Sent from my Desire HD using Bimmer App

+2

Low voltage problem, I agree.

Originally Posted by BMR_LVR

As odd as it may sound, I recommend that you have the alternator checked. Your symptoms seem electrical in nature and I have seen others who got the dreaded trans program error and the fault was the result of a bad alternator.

Hope this helps.

I had similar issues a little while ago with my 90 525i, took apart the alternator to find the brushes worn all the way down. Bought me a new set and soldered them in for a grand total of $6.44.

Take your car to autozone and have them test your alternator using their digital battery meter. Or use a voltmeter and google or youtube for the methods involved.

Interestingly enough, the car randomly decided to start running perfectly fine New Years eve. It ran fine again today. I took it to Auto Zone today and had a charging system test done that read 14.1 volts. The battery test failed but the test was done on the jump terminal not the actual battery. It read 12.39 volts.

Originally Posted by Bimmerfan84

Interestingly enough, the car randomly decided to start running perfectly fine New Years eve. It ran fine again today. I took it to Auto Zone today and had a charging system test done that read 14.1 volts. The battery test failed but the test was done on the jump terminal not the actual battery. It read 12.39 volts.

Did they put a load on the system or just use a digital multimeter? I assume from your post that the trans program error went away. That's great. It also tends to indicate to me that it was related to your charging system. I hope you can determine what the cause was or it is likely to happen again at the most inopportune time.

Originally Posted by Bimmerfan84

Interestingly enough, the car randomly decided to start running perfectly fine New Years eve. It ran fine again today. I took it to Auto Zone today and had a charging system test done that read 14.1 volts. The battery test failed but the test was done on the jump terminal not the actual battery. It read 12.39 volts.

12.39V is not normal (the low reading is not due to the jump terminal contact), especially considering that you drove to autozone, which means your battery should be charged.

If your battery is fairly new (how old is it ?) then you clearly have a charging system problem. Even if it is not new, then it is nearly dead and you must change it immediately.

Did they test the reserve charge or cold cranking amps (cca) using the digital battery testor ? This will tell you how decent your battery is. A reserve charge of less than 30% means your battery needs to be replaced.

If your battery is not that old, then they didn't test your alternator properly with the meter. It needs to be tested under load, no load, at different rpms, while starting, etc. Sounds complicated but can be done in about 5 minutes. Please google and read up for the details of this. Counter reference against several different websites to make sure you've got all that you can on this subject. Youtu be might have useful videos where the chap explains the stuff as he does it and that's a way to learn or corroborate what you know.

And then, go back to the autozone, use their meter, and get them to test it under all the conditions that they need to. Guide them accordingly. Or use your own voltmeter/ digital multimeter and test it at home yourself. Most portable dmms cost $5 shipped off ebay, and probably around there at walmart. They will do.

If your basic symptoms that you wrote about are electrical related (on this I have no clue), then I agree with Steve that these problems will reappear, and soon. Your gremlin is still out there.

You can not do a comprehensive starting and charging system test with a hand held multi meter.

The battery, alternator and starter all need to be tested under load, a dmm will not do this.

I agree, the battery is probably bad. If it was at 12.xx V in a static state, under load it will probably test bad. If so, it is putting additional strain on the alternator until it is replaced.

Originally Posted by snowsled7

You can not do a comprehensive starting and charging system test with a hand held multi meter.

The battery, alternator and starter all need to be tested under load, a dmm will not do this.

I agree, the battery is probably bad. If it was at 12.xx V in a static state, under load it will probably test bad. If so, it is putting additional strain on the alternator until it is replaced.

Well, I usually blast my radio, switch on my low and high beams, cabin and dash lights, a/c, rear demister, fog lights and hazards, and that suffices as load for me. I test the alternator for the voltage loss during crank, then its stable voltage, then with rpms up at 1500, and then at 3500, and then back at idle, with load, and the entire cycle again without load. The dmm is switched to 20v and in view all the way, to monitor its behaviour at various points.

Is this a satisfactory test?

Not really.

You want to know how many amps the starter is drawing. You need to put a load on the battery with the car off to test reserve capacity.

What you do not have is the ability to test amperage draw, which is much more telling than small voltage drops. You can make a guess using your method, you will KNOW when you are done with the proper test done on the proper machine.

Originally Posted by snowsled7

Not really.

You want to know how many amps the starter is drawing. You need to put a load on the battery with the car off to test reserve capacity.

What you do not have is the ability to test amperage draw, which is much more telling than small voltage drops. You can make a guess using your method, you will KNOW when you are done with the proper test done on the proper machine.

Ok a couple of things.

1. Thank you for the video. Its good to know what the precise test is like.

2. What you have written above relates purely to the battery, not the alternator.

3. There is a new type of dedicated digital battery tester being increasingly used, that can also test a battery's cold cranking amps (also known as reserve charge) along with watching other things like voltage. I believe a new battery's cca is around 750 on the meter (the ratings units are usually not stated on the meter). As long as your cca is above 25% of this figure (i.e. 187.5, lets call it 200 for ease of recall, that's only 27% so the error is not too great). I would have this tested once a year for free and take note of this in my little notebook.

4. With this new digital battery tester, there is essentially no need to perform the battery load test. The electronics within monitor all the elements as they should and display the final figure. Please note that some of these digital battery testers do not display the reserve charge in numbers but as a percentage. In that case, please use 25% as the threshold at which you need to get a new battery.

5. At the end of this video, there were links to another video, where I learned something interesting :



This guy says that, as long as the lowest recorded voltage during cranking is ABOVE 9.6 volts, then your battery's cca is fine. This is not a precise test like the new meters used at battery shops, but it is a quick and dirty method. I'm going to assume that he has the correct background/done the proper study to be able to declare 9.6volts as the threshold for reserve charge assessment.

6. Please note that in this video, this chap suggests that you get a dmm with a max min button that would record the maximum and minimum voltages during a test cycle. This can be bypassed by fixing your eagle eye on the meter during cranking, and by holding the crank about 2 seconds longer than needed for successful ignition.

7. I realise that the dmm method and the shops' digital battery cca test method does not tell you the current draw off the battery during cranking. That is indeed nice to know, when you can know, and not knowing it is a weakness. However, I guess it is safe to assume that if the starter cranks the engine and the car starts normally, and the reserve charge is ok, then the current draw must be within specs. If the reserve charge is alright, the alternator seems alright, and yet you are clearly having (or suspect ) electrical problems, then perhaps you can do the proper load test with the classic device.

8. The alternator's capabilities are satisfactorily tested by watching how the voltages change while performing the test cycle that I outlined in my preceding post. Since this is worthwhile imo to understand more precisely, I would recommend that the interested reader google for detailed writeups and explanations on this aspect.

9. My very strong suggestion to everybody is to google for this information and then to run the test cycle on your car right now, when you know everything is in good shape, to set a baseline for yourself. All you would need to purchase is a $5-$10 dmm with a backlight function. Doing this right now also creates a good 'muscle memory' of the procedures and theory involved, and makes it easier to recall when you actually need it.

Happy New Year, snowsled7.



rgds,
Roberto

There is no way the DMM you are talking about in your post is $5-10. Yes, you can buy a cheap one but again, you can not test for amperage.

If you had payed closer attention to the video, it does indeed test the alternator. Again, not for just voltage but, for amperage output which identifies a failing alternator. After all, what good is an alternator that is only providing 10-15 amps but because it does, you get the same voltage reading as if the alt was fully charging. That is the flaw in your test.

The battery draw down number of 9.6V is provided by the manufacturer of the machine itself based on the load it applies.

As can be seen in the video, a complete starting and charging system test can be completed in about 5 minutes. Most shops charge $40-60 for this service. Buying the wrong part will cost you more than the test.

I made a mistake. I said digital multimeter instead of digital battery tester in my earlier post. It has been corrected appropriately.

Yes the vid you posted tests for amperage, and a cheap dmm (or any dmm) would not test for that coz it can't handle 200-300amps. I agreed to that.

I would advise spending the $40-$60 that you mentioned only after doing the free tests at autozone with the digital battery tester, running through the on-car load cycle , and everything still seems ok, and yet you have problems which might be related to poor charging. Such low amperage related poor charging, undetectable through the diy load tests, is relatively uncommon so it would not be in the "low hanging fruit" category of things.

I do not know what tests they perform at autozone becaue I would NEVER let parts store clowns hook anything up to my car.

Most failing alternators go slowly at first causing problems like the ones the OP is having. They can easily be detected by using the proper equipment as I have shown. You have ZERO basis for stating this is uncommon or unnecessary. THIS is how it is done when "quick and dirty" proves to be as worthless as it sounds.

So, my reccomendation is to get the systems checked. It eliminates all the variables and gives concrete proof of component condition from alternator, battery, starter and all the cables that connect them.

The tester you show on the vid is likely in excess of a $100 tool. The cheap DMM will not give you the results the corret test procedure will. End of story. I am not sure why you keep pushing

That's because I had a buggy alternator, and this cheap dmm method identified it as such, and I did not have any electrical problems or symptoms, or failing batteries, anything like that. When the alternator was taken apart for rebuilding, some of the diodes were busted, some of the coils were burnt, etc. So I speak from personal experience. Pretty good for a quick and dirty test, I must say. Of course, the tester you refer to would have been more specific about what was likely wrong, as it generates more pertinent test data.

So, the quick and dirty, in this case, is fairly adroit at indicating charging system problems.

Both parts store clowns and unknown mechanics should not be allowed to do anything to the car that you don't understand ahead of time (they are obliged to explain to you if you ask, if they get irritated, go elsewhere), and you should be there watching carefully when new people are doing things to your car.

Okay I'm back! Sorry I was on a mini vacation with my daughter. Looks like we had quite an interesting conversation going. As an update the car returned to its same problematic routine and yes I definitely need to check the charging system more. Either way I will be replacing the battery this week as it is 3 years old anyway. I also have access to an "AUTEL" scanner which I used to scan the EGS (TCM) and got an error code 11 "Engine Speed Signal n-mot" and I have also noticed a direct association between the tachometer dropping and the transmission going into limp mode. I have also noticed the tachometer has gotten more erratic and when not dropping to 0. It seems as if it is not reading correctly. Also, I noticed the problem is more prevalent the colder it is here in south florida. (under 75 degrees) Either way, I will update after I replace the battery and recheck the charging system. Thanks everybody!

P.S. there are no DME codes.

Also check all cables, terminations and grounds you can find for clean/tight.

My car has a rough idle upon startup. Could it be my alternator? Batter is new within 1.5yrs...

I dont know when or if even ever my alternator was replaced or serviced...

You can test alternator VOLTAGE easily under load but you need other equipment to test OUTPUT/CURRENT under various conditions. Some of us have bought that equipment - some take it to others for testing. VOLTAGE is guide, as you can get a low CURRENT situation from a faulty unit.

Originally Posted by Monsignor

My car has a rough idle upon startup. Could it be my alternator? Batter is new within 1.5yrs...

I dont know when or if even ever my alternator was replaced or serviced...

If your dmm reveals stable voltage while at idle, then its not your alternator at all. Fortunately, it is a simple test and the dmm is just $6.

http://answers.yahoo.com/question/in...8125811AAf1bPI

Didn't realise a bad alternator could cause a rough idle. If it is, please purchase the upgraded alternator...240amps. Its rebuilt. Around $200. You'll just need to add an additional 5 feet of 4 gauge cable from your battery to your alternator.

I assume that you've checked for vacuum leaks (including the vcg ), your icv and tps is clean, your plugs, plug wells and coils are fine, and that you've done the disconnect test for other devices including the o2 sensor and the ects in particular, and there are no useful stomp codes in evidence, and your fuel filter is not clogged.




rgds,
Roberto GS

Originally Posted by robertobaggio20

If your dmm reveals stable voltage while at idle, then its not your alternator at all. Fortunately, it is a simple test and the dmm is just $6.

http://answers.yahoo.com/question/in...8125811AAf1bPI

Didn't realise a bad alternator could cause a rough idle. If it is, please purchase the upgraded alternator...240amps. Its rebuilt. Around $200. You'll just need to add an additional 5 feet of 4 gauge cable from your battery to your alternator.

I assume that you've checked for vacuum leaks (including the vcg ), your icv and tps is clean, your plugs, plug wells and coils are fine, and that you've done the disconnect test for other devices including the o2 sensor and the ects in particular, and there are no useful stomp codes in evidence, and your fuel filter is not clogged.




rgds,
Roberto GS

The rough idle is only for a minute when warming up after start up. And "warming up" is not to mean only cold startups.

My plugs are new, coil boots are new, new valve cover gasket, all hoses are new. I've never had a successful stomp test procedure, i dont know why.