Starting Issue

M

miscbrah

Member
Hello everyone!

I have 2006 z4 3.0si that's been having some intermittent starting issues. The car has very low mileage, just over 33k now, and is driven sparingly.

- The battery is about 2 years old, AGM type
- Cold voltage is usually 12.3v to 12.4v (the car has always had a parasitic drain of some kind)
- Cranking voltage at the battery drops to 10.25v
- Voltage at idle is 14.47v
- Wouldn't crank, took the key out, tried again 2x and it started

At first I thought there was no click at all and assumed it was the ignition switch going out. It must have been too loud in the parking lot where it gave me trouble to hear the click first go around.

Today I measured the cold voltage and went to start the car, heard a click but it didn't turn over. Trying twice more it did turn over and start.

If there's a click, than I assume it's not the ignition switch or clutch switch?

Any other definitive tests I should run? I do have a Foxwell NT510 scanner
 
Take a read of this to see if you can at least rule it out.
https://z4-forum.com/forum/viewtopic.php?t=146806
 
Coming back to this, fairly certain it's the starter.

Today:

  • Heard a click, no engagement
  • Voltage dropped from ~12.7 (or ~12.5, can't recall) to ~12.11 so something is drawing power
  • Multiple attempts eventually gets it to start and voltage drops to 10.75 - meter is on the battery and set to record minimum

Is there an easy way to access a pos/neg that feed the starter with a meter to rule out the ignition switch or clutch switch?

edit - found this on youtube, looks very straight forward
https://youtu.be/1twcbx0ng6Y?si=0Qp6YONLXyLLroWP
 
Tested the voltage across the solenoid as shown in that video.

Seeing full 12.4v on the hot side of the solenoid, measuring the voltage off of that copper wire on the other side of the solenoid was a little more difficult but it didn't seem to get 12v+ when it failed to start.

Put in a new ignition switch today to see if that resolves it.
 
Update - intermittent issue persists after ignition switch replacement so it's got to be:

-EWS
-Grounding strap (looks fine)
-Starter
 
miscbrah said:
Update - intermittent issue persists after ignition switch replacement so it's got to be:

-EWS
-Grounding strap (looks fine)
-Starter
Click to expand...

I'm assuming you have a silver top Z4? If so, I believe the ground strap can be access down the left hand side of the engine. Couple of 12mm bolts..or something like that. Not sure if the back top engine is the same set up.
Ground straps are fairly inexpensive, so may be worth trying that first to rule it out.
 
chanlon1 said:
miscbrah said:
Update - intermittent issue persists after ignition switch replacement so it's got to be:

-EWS
-Grounding strap (looks fine)
-Starter
Click to expand...

I'm assuming you have a silver top Z4? If so, I believe the ground strap can be access down the left hand side of the engine. Couple of 12mm bolts..or something like that. Not sure if the back top engine is the same set up.
Ground straps are fairly inexpensive, so may be worth trying that first to rule it out.
Click to expand...

It's an N52, does look like grounding strap is very easily accessible on the left side of the engine bay
 
The part number for the ground strap is 12427552638. It's around £50 from BMW, but you should be able to get cheaper ones.
 
chanlon1 said:
The part number for the ground strap is <a href="tel:12427552638">12427552638</a>. It's around £50 from BMW, but you should be able to get cheaper ones.
Click to expand...

Thanks, going to look into this
 
I've replaced a starter on my M54B30 and if the N52 is even close to it, the best tool to buy if you're doing the job yourself is a long neck wrench/spanner.

I got this one and it saved me (and my knuckles) a lot of grief. 👍

https://amzn.eu/d/3lPCE1A
 
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