Power down

[Rory35i]

Hi husband's just been out in the Z4 35i 3.0, it's not been used much recently noticed a few times when taking it out of the garage its been a bit noisy on start up but only lasts a few seconds.

On a short run today when driving at 30 going to 40 mph there was a loss of power just the once so came home carefully with no issues or warning lights.

We have had the following replaced a few months ago,. so ruling out water pump issue.

Ribbed belt
Ribbed belt idler pulley
Thermostat and Housing
Water pump
Expansion tank
Coolant

Going to get a friend to run in diagnostics when he's free, but anyone any thoughts?

 

[Zforbes]

Can you be a bit more specific about the noise on start up?

The exhaust should be noisy for a few seconds until vacuum pressure builds up and closes the butterfly valve in the exhaust.

If it's rough running noise or clattering it would be a totally different question and would be required to understand as to give you options of possibilities.

The drop in power might be linked to this depending on your answer.

Nobody can diagnose this without having more detailed information, all you will get are guesses.

 

[mcbutler]

Hi husband's just been out in the Z4 35i 3.0, it's not been used much recently noticed a few times when taking it out of the garage its been a bit noisy on start up but only lasts a few seconds.

On a short run today when driving at 30 going to 40 mph there was a loss of power just the once so came home carefully with no issues or warning lights.

We have had the following replaced a few months ago,. so ruling out water pump issue.

Ribbed belt
Ribbed belt idler pulley
Thermostat and Housing
Water pump
Expansion tank
Coolant

Going to get a friend to run in diagnostics when he's free, but anyone any thoughts?

Try to get an audio recording of the noisy start up, was it a misfire type of sound?
The 35's are always loud on startup, its a fast warmup cycle to heat the catalytic converters quickly, last around 45 seconds before it come s to rest at tickover.
A misfire sound might indicate a leaking injector, has the car had new injectors? How many miles on the vehicle?