Hello everyone!

I've got a strange issue with my XFR with 23K miles on the clock.
It's a lumpy/rough idle. I've tried to capture it on video using a water bottle as a bubble:
Near the 10 second mark you can see that the water is shaking with a bigger amplitude than before. That is due to the 'lumps' in the engine work.
The rev counter is not moving at all. Also, dealer says that there are no errors. :/
This happens both on cold and warm engine.

The car is still on warranty and my dealer replaced the timing chain, but that didn't help a bit
A month ago the same dealer did a full fuel system cleaning (with chemicals).
Spark plugs haven't been replaced and i'm using the best fuel I can find (100 octane).

Has anyone heard of such an issue and what can it be?

Thanks in advance.

 

Just as with pretty much all similar problems it is impossible to accurately diagnose over the internet, especially if there are no codes.
First of all get yourself a decent OBD2 code reader (I use an iCarsoft i930), you never know what it might show and they always come in handy anyway.
Next, one simple thing that sometimes causes a rough idle is dirty MAF sensors (especially if the car has K&N air filters or similar), so cleaning the MAF sensors might help or at least eliminate one possible cause. They are a doddle to clean, remove 2 Torx bolts (T20?) from each one, unplug the electrical connections, take them to you workbench and spray the wires (two in each sensor) 5 or 6 times with specific MAF sensor spray cleaner, allow to sit for a few minutes them reinstall.

 

Probably my f-type MY2014 33'km shows similar behaviour when idling. Occasionally i get very short periods where one cylinder is missing. I can feel the car shaking a bit and with the hood open and the engine cover removed a clunk noise from the SC is noticable too. No codes , no visible change in idle speed . Behaviour started with about 15'km but gets continously worse over the time. Engine runs fine otherwise so i didn't do anything up to now , but i think the problem is caused by a bad injector which can't handle the very small amount of fuel necessary during idle speed any more. Failing injectors are a well known problem on this engines.
So i will wait until the engine roughness control in the ECU will throw codes and hopefully the codes will give some hints where to start with.
Regards
Ulrich

 

My bet is on fuel delivery. Possibly a bad injector.

 

Yeah, I'm with Big Will and Ulrich - smells like an injector to me, as I feel like anything ignition related like a failing coil is usually picked up pretty well by the ECU which would throw a code. Unfortunately the only way you're likely to diagnose it is to get a decent reader on there, a lot of the pricier ones (or the dealers with official SDD) can do live data capture and look for anything that seems off like any misfire counts on cylinders etc.

If it does turn out to be injectors, note that you can get a full set of 8 new genuine Bosch ones for a lot less than a dealer will want for them.

 

Wow, that dealer just ripped off Jaguar for a new timing chain. That's not cheap, and the last thing to suspect when the car only has 23K miles!! I am sorry you had to have your engine molested like that for no reason.

It's most certainly fuel or ignition. Timing chain!!!??? LOL!!

 

Hello everyone!

I've recently replaced spark plugs and now I feel that the vibrations are far less noticeable. But I need to drive around a little more to be sure.
I'll let you know about my findings. But it looks like the case was with the spark plugs since i'm almost 100% sure they've never been changed during the 23K miles and the car might have been fed with bad fuel.
As far as for injectors - I'll still keep an eye on them, but I'm a bit hesitant about them since there is absolutely no loss of power and the car revs up super quickly without any hiccups.

Thank you all for your support and ideas!

PS: Such an amazing car!

 

Nope, sorry, wishful thinking. Nothing really changed much.

Next in line to diagnose are:

• injectors
• MAP sensor
• Timing chain angles
• throttle valves for air leakage/cracks
• spark plug contacts/wiring (not the plugs themselves)
• ignition coils
• air leakage in the intake system

Wish me luck and patience :|

 

Good luck! I feel like MAP sensor and Timing chain angles are likely to throw codes if they were too far from spec, though it's of course possible that they're still "within spec" but enough to cause roughness.

If this was me, I'd do the following. To eliminate air leaks:

• Physical check of all breather pipes - especially the 90° bends where they connect into the rocker cover. Maybe even (carefully, they go quite brittle over time) remove the breather pipes and check that they're airtight. Also check vacuum lines to supercharger.
• Maybe pull throttle body and check rubber gasket

However, I feel like air/vacuum leaks would cause more obvious, and more frequent roughness, and at that point, I'd be getting a code reader that supports datalogging (dealer or independent mechanic should be able to do this) and log any values associated with:

• MAP/Intake sensors
• Fuel Injector Duty Cycles
• Ignition adjustments
• Timing signals, especially "desired" and "actual" cam angle adjustments.

You should be able to then view this data on graphs over time and I'd be looking to spot from the graphs what the ECU is "trying" to do when the idle gets shakier.

Failing that, just making sure that there are no misfire events logged for specific cylinders (which may allow you to narrow down the injector(s) that's causing a problem) and also just general voltage/resistance tests of MAP sensor, MAF sensors, etc. This Jaguar training manual contains quite a bit of information about what values you should be seeing for these components.

 

The only other thing I can think of is, I've had a couple GM cars do a rough running when the water temp sensor is either bad or come un plugged.

 

Ever find out what the issue was?