Hello,
I have been here for a while, and I have researched this issue and read tens of pages on these forums for a definite solution but I haven’t found any. So, I decided to make a new post.
I have a 2012 XJ Portfolio with the 5.0L Supercharged engine. Within the last year or so, I noticed a hesitation in the way the car accelerates below 2000rpm. There would be a small pause, followed by a surge in delivery. Obviously, it is not comfortable nor entertaining as a driver.
I have taken the car to different workshops including the dealer. The dealer claimed the car has no fault, just because the computer didn’t throw any codes. Not convinced by their feedback, I took it elsewhere and I have replaced the following, but with no effect: fuel filter, transmission fluid filter, air intake tube, and 2 of the 8 engine coils.
Additionally, I have cleaned the maf sensors with a MAF sensor cleaner, cleaned the catalytic converter, and used STP’s gold bottle for full system cleanup. All to no effect.
Again, there are no errors on the car, no fault codes on the device, and all the readings seem to be normal. The only exception is probably the Ambient Air Temperature reading and the Intake Air Temperature (IAT) reading which seem to be too high judged by the gauge coloring scheme on the device (Photos attached).
This issue might have been reported here before, for different models and different engines, but as per my search no solution was reported.
I do really love this car, and I dont see myself driving anything else frankly. However, while this issue isn’t critical to most car owners, it is very crucial if you’re an enthusiast who loves his car and enjoys the driving experience it normally delivers. Having to drive the car with a deteriorated experience is absolutely frustrating!
I realize I have wrote a lot (sorry!), but would appreciate any input on the subject. Thanks!

 

The only real symptom you describe is "There would be a small pause, followed by a surge in delivery."
I always like to start with the simple things first before throwing parts at the car, and that symptom sounds like it could be as simple as a sticking throttle plate, which would explain the pause and surge.
So I suggest you try a simple clean-up of the throttle plate and throttle body with some brake cleaner and a MF cloth.

 

thanks for the reply. Well it’s a delay in acceleration response that happens below 2000rpm. Above that, the car seems to behave normally.
Yes, for the throttle cleanup, I failed to mention it but been there done that. No effect.

 

You have some model of diagnostic equipment. Do you have the ability to record real-time data? Maybe you could duplicate the problem while "recording" on your device.

 

I put my bet on sticky/weakened EGR valve.

 

We could do an ECU tune which would bump up responsiveness as well as lots more power and also do full diagnostics and logging while at it which will help to figure out any potential issues on the car.

 

Could be. But as I heard they’re bloody expensive to replace, I would prefer to eliminate the lower cost stuff first.

It is worth noting that I just noticed oil level drops midway between service intervals by 1 liter. This is the second time in a row this happens. Also the engine shakes roughly when I opened the oil cap when idling. No oil spills on the cap nor strong suction preventing the opening.

given all the above, Could it be that I have bad PCV valves?

 

I noticed you mentioned the fuel filter? These are not serviceable and are integral to the in tank LPFP.
Did you also replace the in tank pump?

You should get a check engine light if the engine is running and the oil fill cap is not in place?

You could replace the PVC diaphragms? They are not expensive and easy to install once you get to them!




But any of this will set codes so I am puzzled. Any chance you can find an independent with SDD?

Is there an EGR valve? Can't seem to find it?
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Thanks for the thoughts. Well, yes I am absolutely puzzled that I have the symptoms but without the codes.

No, the pump wasn’t replaced. Only the filter as the mechanic suspected a dirty filter.

As for the oil cap, I took it off and put it back in one second or so — the moment I noticed the engine shaking.

As for the PCVs, I just ordered them and should receive them in a day or two. Decided to get them replaced regardless as dropped oil level and engine hesitation point towards them.

As for the EGR, someone here suggested them. I am not sure on their location either!

I will do the PCVs and will let you know!

 

But that's what I am getting at. You can't change the filter because it only comes with the pump?
Are you sure he did it?

Does your mechanic have the SDD? I think your codes are deep in the car (Maybe?).
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Hey guys. Was there any diagnosis of this issue or were you able to resolve it? I just started having similar issues about an hour ago with my 11’ XF 5.0sc.

 

So here’s my update on this saga. I have found another “fix” that doesn’t work, as well as a “fix” that DOES WORK - but only momentarily! 😅

The one that didn’t: I just replaced the MAP sensor and performed transmission adaptation. The jerking isn’t removed, but it could be slightly “smoothed”.

The one that worked momentarily: car in ignition with engine off, press the accelerator slowly and then release it three times. Then switch off, and on again. The car would then perform like new. Beautiful!

But, it won’t last long and the car would return to its erratic behavior.

Now, with that fix in mind: what could it be? Is is an issue with the pedal? Or with the throttle body? And what’s the remedy?

Any ideas would be appreciated!

 

My second WAG is a faulty TPS (Throttle Position Sensor). AFAIK not expensive and easy to replace.

 

Again ALL of these things set codes?
You can keep throwing parts at it but until you do some real troubleshooting it's all a guess?

Have you ever got the car hooked up to SDD so you can properly scan for errors?
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Kindly excuse my ignorance, but can you explain what an SSD is? And how it differs from an OBD2 scanner like Linova?

 

Yes it's SDD= Symptom Driven Diagnosis.
This is the Jaguar dealer service tool. All the aftermarket ones can't see as deep or as detailed as SDD. It is not available to the public but many on this forum including myself have it. It's absolutely necessary because of the complexity of the car.

I am afraid there is something that the aftermarket scanner simply can't see?
Now this is a guess but until the car has been connected to SDD and checked we won't know. You have done a number of things but still have the problem.
Might have to consider going to a dealer for diagnosis?
Would that be possible?
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JLR does make SDD available by subscription on the JLR Topix website.
Just as with the Topix subscriptions for the technical manuals, SDD can be subscribed to use for short or longer periods as needed - a day, a week, a month or year.
The SDD subscription is separate from the technical manual subscription.
And to subscribe, you must create your 'account' to access Topix, no cost to open your account, but creating a password is part of opening an account for an individual.

This is a link to the Topix website:

Home | TOPIx (jlrext.com)

 

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