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During the cold snap we had at the start of last month the battery in my car went flat. Charged it and didn't think anything more of it. At the end of the week before last, flat battery again. Couple of days later I got a flashing CEL which turned out to be triggered by a misfire on #8. Pulled the coil to discover quite a bit of oil in the plug well. Cleaned out the oil with solvent and degreaser and cleaned the coil. Swapped the coil with #7 and test drove the car. Within a mile recorded a misfire on #7 to the point of bringing on the EPC light and shutting down the cylinder. As I needed the car PDQ I bought a cheap aftermarket coil to keep it going. Nope, still reporting a misfire on #7 and EPC almost immediately. Annoyingly, at that point my trusty old VCDS laptop gave up the ghost so I had to buy a new one (I'll gloss over the hours I then spent messing about trying to make Windows 11 less annoying for a user with a mental age greater than single digits). Next day the battery was flat again and I'd had enough of it so bought another. Today, fitted the new battery and moved the new coil to #6 to see if the coil was duff.
Test drove the car then scanned it. Other than a couple of longstanding minor faults that I haven't got around to fixing yet it was clear - no misfire on any cylinder. Drove it then scanned it again - still no misfire recorded.
It's been a very frustrating (and expensive) week and a half.
At some point I'm going to try the old coil in my other half's car (they're easier to get to than on the RS) and see if it works OK.

Low batteries on these things throw up all manner of "not a real fault" issues, even if you recharge them via driving for an hour or so they still seem to throw random stuff without a full "out of the car" recharge or a replacement battery (depending on its age).

Laptop - I'm still lucky, my VCDS laptop is Win7 from about 2010 and has just had the battery in it replaced so I'm good so far, really not looking forward to the day I'm forced into Win11.

That was what I'd concluded. The battery still had a year and a bit to go on it's 5-year warranty but who (except my father) keeps receipts that long? Still, the starter seems to spin a lot better with the new battery but I think I'm going to do a bit more digging this week as I've just driven through town and when idling at traffic lights there's been a sensation of slight 'miss'. It's due a set of plugs anyway.
Realised that I can't try the old coil in the car of SheWhoMustBeObeyed as it uses a slightly different design.

My old laptop was one I'd bought for my daughter to take to university when she was 18 (she turns 33 this year) that I dug out and upgraded to Win10 a year or so back when my previous VCDS laptop (another of her hand-me-downs) failed. Looked like a fault in the motherboard display output as the screen turned red then died - still worked with an external screen but that was a bit awkward for mobile use.

Jim Haseltine wrote: ↑

Sun Feb 04, 2024 11:15 pm

The battery still had a year and a bit to go on it's 5-year warranty but who (except my father) keeps receipts that long?

I keep mine in a small plastic bag (the type banks used for coins) and put it under the battery strap. I'm due a new battery later this year based off age, oh Joy!