5.0 Supercharged, rough idle

[8bit]

New (to me) 5.0 XKR has a slightly rough idle - every few seconds it sort of feels like a misfire, can feel and hear the engine revs drop very briefly. Had the car almost two months now, I think it has maybe used a little bit of oil (quarter of a litre if I read the electronic dipstick right) in the 1000 miles I've done since collection. Car showing 47k.

PCV issue perhaps? Is it possible to check that?

[fatboy b]

If it’s giving a rough idle, then I’d get in plugged in. It’ll have an error code logged. Otherwise you’ll spend ££££s replacing random things.

[8bit]

I did that last night (I have SDD on a laptop with a JLR-approved hardware interface), no fault codes showing that could relate to rough idle. I did perform a reset of the ECU learning adaptions and, *touch wood*, so today the idle has been nice and smooth again, but I'm not expecting to be out of the woods that easily yet...

[fatboy b]

Mines been in the dealer for 1 week and a half. Last I heard was last Thursday when they were about to renew the timing chains under warranty. Seems the 5.0 timing chain saga lives on, and mine’s a 2015 car.

[Northern.N]

Niall, have the plugs been done? I changed mine at 70K and they made quite a difference.

Can also be linked to vac hoses, air intake hose, PCV, MAF etc etc.
If its not logging fault codes then it might be the smallest of air leaks if its searching for revs/ running rough.

At cold start or just whenever idling buddy?

[8bit]

fatboy b said:

Mines been in the dealer for 1 week and a half. Last I heard was last Thursday when they were about to renew the timing chains under warranty. Seems the 5.0 timing chain saga lives on, and mine’s a 2015 car.

What is yours in for? Not aware of any common issues with timing chains on the 5.0 engine, that's not been a "thing" really since the 4.0 V8.

Northern.N said:

Niall, have the plugs been done? I changed mine at 70K and they made quite a difference.

Can also be linked to vac hoses, air intake hose, PCV, MAF etc etc.
If its not logging fault codes then it might be the smallest of air leaks if its searching for revs/ running rough.

At cold start or just whenever idling buddy?

Don't think the plugs have been done, car shows 47k miles and is 9 years old so would be due next year. Unfortunately changing them on the 5.0 engines means removing the supercharger intercoolers, I might just leave that to a garage to do...

I *think* the ECU adaptions reset may have sorted it out, it was fine yesterday after doing that the previous evening but I'll watch and see if it comes back. It was only doing it on idle and only once the revs had settled down to the normal idle level (about 600-700RPM I think), not on cold start fast idle.

[fatboy b]

Looks like chains or a sticking tensioner. The front of the engine is stripped and the S/C off. So much for the updated ‘design’. Some of the early ones failed with stretched chains.

[8bit]

fatboy b said:

Looks like chains or a sticking tensioner. The front of the engine is stripped and the S/C off. So much for the updated ‘design’. Some of the early ones failed with stretched chains.

Wouldn't that be noisy?

[fatboy b]

Yep.

https://youtu.be/S9aMmKKo5pY

[8bit]

OK, mine doesn't sound like that. Wouldn't there also be timing-related fault codes? I take it that's your car? What was the final cost to put it right, if you don't mind me asking?

Edited by 8bit on Monday 10th December 13:38

[fatboy b]

8bit said:

OK, mine doesn't sound like that. Wouldn't there also be timing-related fault codes? I take it that's your car? What was the final cost to put it right, if you don't mind me asking?

Edited by 8bit on Monday 10th December 13:38

It’s an exrended warranty job, so no idea yet really, though I’ve been told a chain and tensioner job is about £5k. Confirmed today as a shot tensioner. Unsure how much of the timing gear they’ll replace though. And yes, my car in the vid.

[8bit]

fatboy b said:

It’s an exrended warranty job, so no idea yet really, though I’ve been told a chain and tensioner job is about £5k. Confirmed today as a shot tensioner. Unsure how much of the timing gear they’ll replace though. And yes, my car in the vid.

OK thanks for that. What was it that first made you think there was a problem, was it the noise or something else, e.g. engine warning lamp, fault code, poor idle, poor performance etc.?

Some of the noise in that video sounds like fairly normal stuff to me, DI injectors for one, but then I can't tell the relative volume from the video. How many miles are on your car?

[fatboy b]

The car has 45k on it. I know there’s a lot of Injector noise, but there’s an overriding tapping and a slight knocking. N/S tensioner isn’t holding pressure when the engine is off.

[Jbliss]

Mine does the same sometimes...Same thing of no codes etc. Interesting. Keep this updated with progress!

[fatboy b]

Will do. Repair Authorised, and parts ordered.

[8bit]

Jbliss said:

Mine does the same sometimes...Same thing of no codes etc. Interesting. Keep this updated with progress!

So just a very occasional stutter on idle? Idle is otherwise steady and smooth, just the odd little "blip" but no other symptoms?

fatboy b said:

Will do. Repair Authorised, and parts ordered.

Fingers crossed that's you sorted. I have third party warranty for six months on mine (wasn't an approved-used car) hopefully I don't have as serious an issue as yours, not sounding like we have the same symptoms anyway.

[fatboy b]

Picking up the R-S tomorrow all being well. Two new chain tensioners fitted.

[8bit]

fatboy b said:

Picking up the R-S tomorrow all being well. Two new chain tensioners fitted.

Good news. Have you got it back yet?

Mine has been mostly fine. Interestingly it only seems to do the odd "misfire" sort of thing while idling in a forward gear; doesn't seem to do it in neutral or park. It's not bad, certainly not getting any worse, no codes are showing and SDD finds nothing when I ask it to diagnose a rough idle symptom so will just keep an eye on it.

[fatboy b]

Get it back tomorrow. Would have been today, but on reassembly there was a headlight out, which they are expecting me to pay for. We’ll see.

[8bit]

You back in the car yet? All resolved? (fingers crossed)