Delayed engine start

[mibal]

I have a 530i recently fully serviced. However, last few days when I turn the key to start the engine, it makes a noise and the TV screen flickers before it starts after a delay. I dont think its the battery as all electrics work. Could it be the spark plugs?

[albert]

Delayed starting could be because of following reason:

Spark plug you are right. or Ignition coils are weak.

Remove one by one when car is one and check if spark delivery is fine, test in night so that you can see the spark is strong enough or not.

Battery is weak to deliver sufficient cranking amps.

Battery getting weak starts with this issue, as every battery has certain reserved cranking amps (400 - 800) to be deliver to start the car. If its getting weak this drama starts as car get starts in few self. Best way to check this is check the battery eye (only on main free battery) on top of battery, if its in fading color and appear in bottom then that means battery getting weak, if its fluorescent dark color and float on top then it means fine. In maint battery, you dont have that battery eye for health indication, check and top up the battery water.

Fuel pump may be weak as well.

Only way to check this is to check thru shrader valve in engine hood next to fuel rail, behind or on any side of engine. Half key the engine (dont start) and after 30 secs when fuel prime stops over and clicking stop check the pressure in fuel shrader valve. If its lower than than 25 psi - 30 psi then fuel pump is getting weak and also might die sooner on road. Second and not sure way to check weak fuel pump is hesistation in picking when u floor the throttle from zero.

Starter relay may be going bad.

No reason for electrical failure, its just their mood, age and quality. To diagnose this, swap the starter relay in engine hood fuse box with same amp and color relay (replace with ac relay or fan relay etc, just for testing) overnight and check next day morning when car is cold if it start in single self then get new relay and replace the bad one.

CKPS

Crank position sensor is the second most notorious thing to mis behave after relay. Its slightly expensive to buy and easy to change so leave it on last. If this is failing then you must be noticing some drop in fuel mielage too. And this problem happen on every restart not only in morning. CKPS would cost 500 - 800 dhs and another 100 dhs to change it from good mechanic outside (not agmc).

Hope i helped you, and your screen flickering is because car is not starting in first try and that's why screen got on after few second delay which is not related to your delayed starting problem. Once delayed starting problem is fixed, your screen will also stop flickering. Good luck.

[mibal]

thanks Albert, this is very useful information. I checked the battery and the eye is black color. So i understand this means to charge or get a new battery. I will see if this solves the problem. many thanks!

[bmguy]

Black eye means not charged battery. before buying new battery check whether alternator is working or not. As few years back i bought new battery and that also died in 3 days making me force to discover that my alternator was the culprit.

Open the battery terminal which in any case you will be opening to put new battery. Once terminal is disconnected, jump start the car with another car by holding to your car terminals. Make sure ALL ELECTRICS, AC, FAN, Music, Nav etc even door light shud be off. Once car start with jump start, remove the the jumper cable and see. If car dies immediately as you remove the jumper cable means alternator is dead FOR SURE. If car runs fine or might die after 5 - 10 mins then that means your black eyed battery is dead.