Juddering / Exhaust Emissions light

10DD

Member
(3.0si, auto, 103k, ~250 miles a week)

I've had a couple of intermittent cases over the past 2-3 weeks of juddering and loss of power on acceleration (around 2k revs), triggering the exhaust emissions warning light. Normal running for the rest of the journey and the dashboard light turns itself off after 10 minutes.

I've felt a slightly less severe version of the juddering a couple more times this week, but seemingly not enough to trigger the warning light. Recent MPG is around 35 and that's stayed pretty steady. It doesn't seem to occur if you drop a gear before accelerating and it hasn't happened with sport mode engaged. Oddly, felt a slight judder when reversing near the time the issue first happened properly.

From what I've read (people experiencing similar symptoms constantly), the main causes seem to be: ignition coils, an air leak or lambda sensors.

I'm a bit hesitant booking it into a garage without a constant dashboard light (presumably no error code to diagnose) and I've already spent a significant amount on issues/repairs. It's a daily driver, so it's tricky if my garage doesn't have a courtesy car available and I may need to hire something if the Z is in the garage for more than a day or 2.

Just checking your thoughts - is it Ok to continue driving as is and book it into a garage if it either gets drastically worse / more frequent or is still happening intermittently after a couple more weeks? Or should I get it booked into a garage now and (in leui of a dashboard light) specifically ask them to check the ignition coils and for air leaks (and failing those options, lamdba sensors)?
 
It won't be air leak on the N52. It will have stored the code however (despite the light not being on currently) so getting that code read would be your priority. I wouldn't worry about driving it but get it sorted sooner rather than later.

My money would be on:

1) Vanos solenoids (15 mins job to remove, clean and swap over)
2) Coil packs - piss easy DIY. About £20 - £30 ech.
3) Lambda sensor (precat more likely than post cat)

..in that order.
 
10DD said:
It doesn't seem to occur if you drop a gear before accelerating and it hasn't happened with sport mode engaged
On a less helpful note and not to take it seriously, accelerate harder between gears raising those revs. and drop your MPG from 35 to a very respectable 24 (for a sports car), the car will love it. :D
 
ph001 said:
It won't be air leak on the N52. It will have stored the code however (despite the light not being on currently) so getting that code read would be your priority. I wouldn't worry about driving it but get it sorted sooner rather than later.

My money would be on:

1) Vanos solenoids (15 mins job to remove, clean and swap over)
2) Coil packs - piss easy DIY. About £20 - £30 ech.
3) Lambda sensor (precat more likely than post cat)

..in that order.

Cheers, really helpful. Took her in on your advice and they diagnosed misfiring due to coil pack. Said they double checked by switching cylinders? Replacing seems to have sorted it and thankful nothing too serious.
 
Only just seen this, had exactly the same issue, and had to replace all my coil packs (did plugs at the same time) to cure it. Did you get all coil packs replaced, as normally when one goes more are sure to follow?

Managed to get all six bosch coil packs off ebay for £120.00 and an easy job, around 1hr to change, even for someone of my limited ability.

Glad to hear you are back up and running :driving:
 
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