Early 992.1 C2S lumpy - Page 1 - 911/Carrera GT - PistonHeads UK

Hi guys - just looking for a steer if possible on this. I bought a 2019 992.1 C2S from OPC about 3-4wks ago now. It’s got 36k on the clock. It’s, as expected, a bit lumpy in the mornings but recently - particularly after a week lay up at LHR whilst away on business - cranked for an unexpectedly long time before firing (probably only a second more than usual but felt long) and then proceeded for the entire journey home (80miles) to feel lumpy/bumpy/hesitant mainly at low throttle openings but also when backing off after a decent shove. Almost felt like a coil pack failing but no CEL or other warnings. Sometimes felt like I was driving over cobbles. Interestingly, yesterday I took it out for a punt and was fine when warmed. The supplying OPC is collecting it in a couple of weeks to investigate but any experience of similar appreciated in the meantime.

Coil pack or plugs. Usual culprits for lumpiness.

Good advice. Also - I imagine that you know the following, but just in case this is useful to someone: Generally good preventative / sympathetic driving habits, 1) warm the oil temperature up before giving the car the beans. 2) drive the car without using the turbos for the last few minutes of driving before parking up. 3) fill up the car - wherever possible - from high traffic petrol stations where the inventory of petrol is being replaced frequently. And 4) This last one debatable as I've read some interesting comments on this forum from people in the petrol distribution business, but personally I always use one of the premium, low ethanol fuels with mysterious cleaning additives.

Coil packs are common, but so are the solenoids that control the variable valve timing. Mine started to give similar symptons, before totally failing.

XMA Simon said: Good advice. Also - I imagine that you know the following, but just in case this is useful to someone: Generally good preventative / sympathetic driving habits, 1) warm the oil temperature up before giving the car the beans. 2) drive the car without using the turbos for the last few minutes of driving before parking up. 3) fill up the car - wherever possible - from high traffic petrol stations where the inventory of petrol is being replaced frequently. And 4) This last one debatable as I've read some interesting comments on this forum from people in the petrol distribution business, but personally I always use one of the premium, low ethanol fuels with mysterious cleaning additives. Yes good advice. Re point 2, if I stop at an Mway services or similar, I let the engine idle for a minute or so before turning off. And don’t labour the engine at low revs in a high gear… though PDK should avoid that one.

I'll guess valve lift solenoid

Your symptoms point to one or more of the following: Battery voltage/health degradation (very common after lay-up). Condensation or carbon build-up in the intake or fuel system (especially after short runs or long idle periods). Dirty MAF sensor or slightly out-of-spec sensor readings. Software adaptation reset or re-learning after the car sat. Possible bad tank of fuel (especially if filled before lay-up). Long Crank After Layup Possible Cause: Low battery voltage after a week at LHR. Even a "healthy" AGM battery can lose enough voltage in a week to impact start behavior. Porsche ECUs are very sensitive to voltage, and even a slight dip can cause a longer crank or unusual behavior post-start. Fix: Get the battery load-tested. You might also consider a CTEK charger if the car is often left for a week or more. Lumpiness/Hesitation on Light Throttle Cold start hesitation is relatively common on GPF-equipped 992s due to emissions control strategy (especially Euro 6). However, ongoing low-throttle hesitation after warm-up could indicate: Dirty MAF sensor Minor vacuum leak (less likely) Throttle body adaptation needing reset Poor fuel quality or contamination Slight carbon build-up on intake valves Clears Up When Warm Points toward condensation, sensor recalibration, or poor-quality fuel being burnt off. Could also just be the ECU adjusting trims once up to temperature. What You Can Try / Check Battery test Either DIY with a multimeter (should be ~12.6V+ at rest) or get a load test at your OPC or a local shop. If marginal, even if it "starts," it can still cause weird running behavior. Run a full tank of top-tier fuel Shell V-Power or similar especially if the last tank was before/after lay-up. Log throttle, AFR, and misfire counters If you ve got access to something like OBDeleven, Durametric, or PIWIS, checking misfire counters and fuel trims could reveal more. MAF sensor clean Use proper MAF cleaner very lightly spray easy DIY, just be careful. Or ask the OPC to check this if under warranty. Throttle body adaptation reset If you've disconnected the battery or voltage dipped, it can lose the learned throttle adaptations. A reset via PIWIS or letting it idle for a few minutes with no input after cold start can sometimes re-learn it.

Appreciate all the input guys. I’ll definitely take a look at the battery. On the face of it, it seems fine and the Start Stop is always very eager to engage, unlike other vehicles I’ve had where unless battery is 100% charged, it never stops. It gets used every day but being laid up for a week could be an issue. Fuel - I don’t use anything but Premium Unleaded so doubt that’s a factor. Mechanical sympathy - I’m very hot on this (forgive the pun). I never give it any beans unless the oil is min 90C. I tend to let it idle for 10-30secs to let the turbos calm. All I can say is supplying OPC has been very reactive and agreed to collect the car and leave me a courtesy vehicle whilst they’re looking into it. I’m 125miles away so appreciate their stance on this. I’ll update when I have some more but useful to know the kind of things it could be so I can have an eye level conversation with them.

Not being used for a week shouldn't be an issue. Or a fortnight for that matter.