Intermittent Starting

[DaveX53.0i]

Alright so I have a 2002 E53 3.0i which occasionally won't start. The issue seems to stem from the positive battery cable as usually after a jiggle it some I can get it started. I really don't mind this however it is a slight pain because I have a subwoofer installed in the back along with an amp. Now before anyone blames the subwoofer I had it professionally installed and I've checked the fuse and all connections in the rear and they seem to be completely fine. If anyone else has had this same issue and found a fix, I'd love to know. Thank you

[mr_robot]

Usual suspect of intermittent starting is usually the fuel pump relay in the glove box. It gets progressively worse and eventually not start at all showing similar symptoms of a weak battery.


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[upallnight]

Originally Posted by mr_robot

Usual suspect of intermittent starting is usually the fuel pump relay in the glove box. It gets progressively worse and eventually not start at all showing similar symptoms of a weak battery.


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Could it be a weak battery? Turning the ignition switch only hearing a click usually mean a weak battery. Using a jump pack at the engine battery jump terminals to start usually indicate a weak battery.

An alternator not alternating to charge the battery could be the reason for the weak battery.

[Qsilver7]

Originally Posted by DaveX53.0i

...The issue seems to stem from the positive battery cable as usually after a jiggle it some I can get it started...

When you "jiggle" it...what exactly are you jiggling or moving? Is the clamp around the positive battery terminal moving...or are you moving the positive battery cable only?


If you can "jiggle" the positive battery cable and it is loose enough to move around the positive battery terminal...then your cable needs to be tightened (at the least).

[DaveX53.0i]

Originally Posted by Qsilver7

When you "jiggle" it...what exactly are you jiggling or moving? Is the clamp around the positive battery terminal moving...or are you moving the positive battery cable only?


If you can "jiggle" the positive battery cable and it is loose enough to move around the positive battery terminal...then your cable needs to be tightened (at the least).

I checked the terminal and it’s tight and doesn’t move at all. I mean more that I grab the red cable and move it around a bit and then try to start, it doesn’t always work the first try but it does eventually.

[upallnight]

Originally Posted by DaveX53.0i

Alright so I have a 2002 E53 3.0i which occasionally won't start. The issue seems to stem from the positive battery cable as usually after a jiggle it some I can get it started. I really don't mind this however it is a slight pain because I have a subwoofer installed in the back along with an amp. Now before anyone blames the subwoofer I had it professionally installed and I've checked the fuse and all connections in the rear and they seem to be completely fine. If anyone else has had this same issue and found a fix, I'd love to know. Thank you

When you say "Won't Start" is it the engine not turning over, or the engine cranks (turns over) but the engine does fire?

You got to be more descriptive in your assessment of the issue.

I have seen more issues caused by "Professional Installers" because they don't understand the electrical, communication systems install in various cars.

[DaveX53.0i]

Originally Posted by upallnight

When you say "Won't Start" is it the engine not turning over, or the engine cranks (turns over) but the engine does fire?

You got to be more descriptive in your assessment of the issue.

I have seen more issues caused by "Professional Installers" because they don't understand the electrical, communication systems install in various cars.

Sorry about that, I mean that when I turn my key and it reaches the 3rd position all I get is a single click and all of my electronics come on but no crank or start. As for the installation of the sub and amp I trust the shop as I’ve had them do work before, as well all of the connections are tight and free of corrosion. Also, if it doesn’t start, It will always start with a jump.

[andrewwynn]

Either completely coincidence having nothing to do with the battery terminal and most likely the problem is in the steering column: ews antenna or ignition switch (or faulty key) else something could be wrong with the BST at the battery.

Next time It fails see if you have voltage at the jump point in the engine bay. If no voltage most likely failure at the BST contact that is somehow opening and closing. If you have voltage at the B+ under the hood the problem almost certainly is key related: switch/ews/key.

Try the other key. If the problem goes away likely bad solder joint on the ews in the key there is a guy will fix for $60

[DaveX53.0i]

Originally Posted by andrewwynn

Either completely coincidence having nothing to do with the battery terminal and most likely the problem is in the steering column: ews antenna or ignition switch (or faulty key) else something could be wrong with the BST at the battery.

Next time It fails see if you have voltage at the jump point in the engine bay. If no voltage most likely failure at the BST contact that is somehow opening and closing. If you have voltage at the B+ under the hood the problem almost certainly is key related: switch/ews/key.

Try the other key. If the problem goes away likely bad solder joint on the ews in the key there is a guy will fix for $60

Not the key, both have the same issue. If it were the ignition switch wouldn't my accessories not work? and wouldn't it not always start with a jump? Also when it won't start, voltage at the B+ is very low, below 1.

[andrewwynn]

Originally Posted by DaveX53.0i

Not the key, both have the same issue. If it were the ignition switch wouldn't my accessories not work? and wouldn't it not always start with a jump? Also when it won't start, voltage at the B+ is very low, below 1.

Incorrect. When an ignition switch fails the most common symptom is that you get inconsistent starts. There are several parrallel switches inside the switch and the starter switch component is a common failure point and exhibits exactly your symptoms when it fails.

That being said, B+ volts low means battery problem. If B+ is low then it's not logical it would ever recover from that and start without a jump unless you have a connection problem somewhere.

If you have a defective battery it can cause very quick drops in battery voltage. I had a battery that would test fine, 550 cold crank amps, start the car at 0°F more than once no problem.

However, if I left the hazards blinking for 8 minutes I would not be able to start the car I would get one click. At that point I would get a very low vBat and would jump start easily.

My case turned out to be a defective battery (shorted plates or something: it effectively had nearly no AH capacity)

New battery fixed it right up