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Intermittent engine misfire after warm start

G

G_S_3_4

PCGB Member
Member
Car: 2010 Boxster S. Problem scenario:
  1. Drive car for 1 hour or so
  2. Park up for 1 hour or so
  3. Start off, engine starts to misfire after 20 yards or so, check engine light comes on; OBD analysis says cylinder 5 (only)
  4. Stop engine; drive off again, no misfire or check engine; so problem appears to be random
  5. Misfire never occurs after cold start
Any ideas?
 
Intermittent problems are always difficult to track, but if the error code relates only to a single cylinder most likely it’ll be sparking plug or coil-pack related.

Jeff
 
Swap coils in cylinder 5 and 6, if the error goes to 6, you will know it is the coil.
Many people change all coils. Not essential. When I had a fail on my 2010 Cayma. S (no 4, 4 years ago), I changed all three on that side (they are not too expensive and the extra work is minimal). I kept the working coils as spare in case another went. All good so far at 93K miles.
 
Thanks all. In the "good old days" of engine management there was a separate cable from the distributor to each spark plug. What's the setup in this case - is there a separate cable to get, or is it a kind-of "octupus" setup where all the leads are a single unit?
 
Had exactly this fault on my 987.2 in Austria on a touring holiday.
#5 cylinder miss-fire just as you describe.

It was the coil pack on #5.
Had a spare in the boot (!).
Had it fitted (RAC Euro cover) and perfect after, ran a dream, but it did before the miss-fire!
Changed all 6 later, kept the rest as spares, youngest one in the boot at all times.
 
G_S_3_4 said:
Thanks all. In the "good old days" of engine management there was a separate cable from the distributor to each spark plug. What's the setup in this case - is there a separate cable to get, or is it a kind-of "octupus" setup where all the leads are a single unit?
Click to expand...
I remember the good old days - points, condenser, distributor .... I also remember dreading driving through puddles, wrapping the distributor in a marigold glove with the HT leads fed through the fingers, spraying everything in dampstart and spending a saturday every few months "doing the timing" and "oiling the advance retard" with "3 in 1". Don't get me started on waiting in a lay - by, bonnet up - trying to stop the HT lead arc'ing to the nearest random piece of chassis and screaming like a wounded animal as the "belts" travelled up my arm every time touched anything while watching the pretty sparks go anywhere except the spark plug ( of which I had several spare in the boot - just in case).

I don't miss them ....
 
911hillclimber said:
Had exactly this fault on my 987.2 in Austria on a touring holiday.
#5 cylinder miss-fire just as you describe
Click to expand...
I believe that #5 is most at risk due to poor cooling air flow. It is tucked up close to the rear bulkhead out of any airflow under the car and away from the engine bay cooling fan which draws air in through the right air intake.
 
I think you are correct.
The coil pack failure mode is generally down to heating issues that cause the breakdown and #5 is the hottest spot.

The mechanic in the Austrian garage knew this already, and the plug-in analyzer confirmed this one had failed.
The car when cold ran perfectly but soon miss-fired when hot.

He was surprised I had a spare, but a few months before the trip a friend with a 986 had this failure and the cost to sort it in Italy was over £1000 and 3 days.

We got another coil from the local OPC where we were staying same day, 60 Euros so continued the holiday with a new one in the boot. Still there.
The OPC were really helpful and offered a lot of help.

The RAC cover was superb and we only lost 3 hours in our holiday, so it all worked out well and I learnt a lot.

Keep a spare in the boot!
 
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