BMW E85 Z4 Slow Start Issue

[skullandbiscuits]

Any advice on how to diagnose a slow startup issue. I’ve got a BMW Z4 2.5Si with a lethargic startup.

The battery was new last year, and it’s got the same symptom with a jump starter attached to the battery, so I know it’s not the battery.

Got a video here if it helps
https://photos.app.goo.gl/imudMpp3Zd3m8Ne16

[parabolica]

Most likely the starter; mine went very quickly from normal to slow to none - maybe only 5-10 starts.

[bodhi]

I had the same issue a couple of years back with my 125i, which iirc is the same engine as the 2.5 Si (N52).

It was the starter, had that replaced and it fires straight into life again. Don't recall the fix price being too bad, although I did do the water pump which was equally close to expiry at the same time.

[E-bmw]

Before buying a new starter remove, clean & refit all major 12v/earth connections between the battery, alternator & starter.

The VAST majority of charging/starting issues are ACTUALLY caused by poor connections on high powered wiring such as these.

What happens is people change the starter/battery/alternator thinking it is the issue & then think they were right to pay £250 (eg) to fix it, when it was just a connection that was disturbed & redone up in the process of change.

This should ALWAYS be the first step for ANY charging/starting issues.

Just had one on my motorhome.

Turn key, just a series of clicks from the starter.

12.7 volts at the battery before key turn, 8.7 volts at key turn.

Battery negative terminal removed/found to be not fully tight, but looked good, replaced it correctly, starts like a good-un, cost £0.

[TheGinger1]

I was struggling to get my N52 330i to start first thing a couple of months back. Eventually failed to start on the day we moved house as trying to leave for the very final time, which was somewhat stressful! Neighbour with leads couldn't get it going either. Recovery arrived and tried a battery pack and it started fine. Eventually traced to a bad cell in the battery. Car has been fine since replacing the battery.

[skullandbiscuits]

Thanks for the advice all

[skullandbiscuits]

I’ll add closure to the thread. I fitted a new starter motor from West Lancs Auto Electrics, and it’s sorted my lazy startup issue.

Yes it could have been earth ground points, but for £98 the car will benefit from a new starter.

[AB]

My Z4M had the same issue, back to like new with a starter. Did try the connections first.