Engine Judder / shaking upon startup

K

k3ab

Member
Hi guys,

got an interesting issue - hoping it is something very simple like spark plugs.

I recently started making more use of my second car during the week, leaving the z parked for 5 or so days at a time.

Upon starting after these 5 day breaks, I often find the engine juddering and shaking for the first 20 seconds or so. The judder is strong enough to shake the entire car.

It then starts to fade and within 15-20 seconds the engine runs smooth again. This ONLY happens when the car hans't been driven for a few days. Once the engine has been running, it can be left off overnight without this happening upon the next start up.

Very odd indeed.

Any ideas what this may be?
 
Mine can be a bit fluffy like its running a bit lean for the first startup butbgoes after 1 min or so driving i put it in sports mode that seems to smooth it out but doesnt shake the car.
Im sure ive seen other posts on this though
 
It could be your fuel line has a small leak in it leading the fuel to slowly drain out and air-locking near some of the further injectors from the fuel rail input. This would lead to you running on fewer cylinders until pressure builds-up. Obviously, the longer you leave it, the more fuel seeps out of the fuel lines near to the injectors, and the bigger the 'lumpiness' until fuel gets through. Take a peek around the fuel lines in the engine compartment especially near the injectors to see if you can see any moist areas that may be small fuel leaks.
 
I also had this problem, changed spark plugs, all was then well for about a month or so and then I had some rough running during acceleration.. Turned out to be one bad coil - changed all 6 and she's run like a dream since.. Super easy to change the plugs and coils yourself.

Cheers,

Nelson.
 
I would say that the coils themselves are probably ok, but the connections are getting slightly corroded perhaps.

My Z4 has been a little stroppy the odd morning, and found that placing some di-electric grease between the coil's conductor and the spark plug works wonders :)
 
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