Hi, I am new here. I currently live in Norway. Before summer, I purchased an XKR, and for the summer, I have been driving without a problem.

I have just changed the two MAF sensors (Hella.)

The car is now running very lean on both banks.

I have gone through the whole intake up until the throttle body. I have sprayed starter fluid around the PCV and intake.

What is the next step? When cold, the car is fine. Just as soon as it gets some temp, it starts running very lean.

I will also attach a video as maybe you experts out there can tell me that the engine at idle sounds fine (to me, it almost sounds like heavy valve noise. Is this normal?). The MAF sensors had both been unplugged as the car was running very lean.

https://youtube.com/shorts/uOe8-pKnI_4?si=L4rNNVuoodm9YRxL

 

Why don't you replace the original sensors and see what it's like then? If it runs fine, the sensors are not measuring correctly for some reason.

It does sound a bit rattley at idle. Is it coming from the supercharger? Snout isolator worn?

Richard

 

I see you have an ability to actively manage the car. So I suggest you change the " engine coolant temperature sensor". If all of the fuel delivery gets the wrong info, it will supply the wrong amount of fuel for combustion at operating temperature.

 

Hi, thank you for the rapid response, Richard. The old MAF sensors have been thrown away. I have ordered a pair of used "low mileage" sensors and will replace the small Orings on there.

This noise does sound like the supercharger sounds worse when switching off the engine, almost like a rod knock.

Is this normal for this engine type? I am new to Jaguar.

I read that this engine was deigned by Jaguar but made by ford since they have the resources?

 

The snout isolator/coupler is a known weak point on these engines and can be changed for a newer design which is longer lasting. I don't have a supercharger but if you can release the pressure on the tensioner such that the supercharger stops spinning for a second and the noise stops then it is the supercharger.

Richard

 

Wow. Getting a part number wasn't easy. Seems Jag parts catalogs from Jaguar, are rarer. I am talking about changing C2Z17977.. sensor.

 

Did you change Mafs to eliminate this particular problem, or for another problem?

Perhaps a stupid question but how did you conclude its running lean?
Does throw a lean code on.both banks?
Or you mean fuel trims show maximum negative trim? (Which indicates too rich mixture picked up by upstream lambdas I believe)
Or are fueltrims maxed out towards plus?
in which case its running lean and I would suspect the single fuel pressure sensor.

And sbout the noise, yes it is too rattly compared to my similar engine.
fuelpumps are always noisy, as are these injectors, but this is more than just that..
How does it sound when reving? Is there a louder knock audible when you select Drive with foot on the brake?
How does it sound when accelating under full load.
Hope its indeed the snout coupler. Fingers crossed.

Good luck

 

Hi Sony, ok I would have never pointed out the engine temp sensor. This is the coolant temperature sensor? As on the dash, the temp garage is still functional but I will do some more diagnosis today and update you.

 

Hi Ekskaar,

I appreciate your input and advice on the following issue.

The two MAF sensors are back to their original parts(no aftermarket.) Orings around the sensors are also new.

The MAF sensors initially where changed together at the same time before of one side had failed(both replaced together from HELLA.)

Codes thrown now are System too lean. Bank 1-2 running lean.

​P0171-00
P0174-00

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Here I have recorded the fuel trims at idle and cold.
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Maxhighend, the dash gauge possibly has its own sensor, in the coolant. But the engine management system relies on the coolant sensor by the fuel injection to "add" to the calculation of how much fuel is to be metered. Like a computer G.I.G.O.

 

With those lean codes I would inspect the intake plastic parts which might be causing a vacuum leak. Especially any that have folds or seams in them. Air box lids that are not installed tightly can also be a source.
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I,m no expert by far but have tried to get acqainted with how my 5.0R works a bit..

I see longtermtrim is in plus 25% both sides, and shorttermtrim almost exact that vallue in opposite side.
Not exactly sure how how that works.

Is there something else done on the car just before the problem occured?
Have the 2 PCV's been checked/replaced yet?
Or did someone install a oil catch can to that system for example? (Look for aftermarket mods...the are often a starting point of misery later on..)

Anyways, since its 2 banks showing the same symptom, you would expect the cause to be in a shared component.

Compared to the programmed fuel map in the ecu, it seems like the engine (thinks it) is getting not enough fuel.

Thinking out loud, this could be by:

-The ECU getting wrong temperature information? Engine perhaps is cold but temp sensor says hot, resulting in ECU map to be fooled and a hot fuelmap fed to a cold engine perhaps?

-The ECU getting wrong fuel pressure information?
it seems to regulate around 60Bar in the link you provided, while desired pressure says 100Bar.
I think (vagely recollect) that is standard behaviour. However, that 60Bar indication could well be 40 or 30Bar in reality, if the sensor is bad..
As far as I know there is no failsafe on fuelpressure sensing on these engines.
If the sensor get off its intrnded settings then that screws up the HP pumps on/off activation giving a too low actual fuel pressure delivery, since ECU thinks its 60Bar, and ECU calculates injector opening duration accordingly, delivering too little fuel to the cilinders.

-Another thing could be the HP fuelpumps are bad. I read it becomes exposed only after 2nd pomp went out as well, since one pump can do the job alone.
For too long I've suspected my HP pumps (and replaced them) while the were just fine.
If you see the pumps buildup pressure while reving or driving, and you see the pumps being deactivated, then that means they produce enough pressure.
You see desired fuel press drop to zero at the moment that fuelpumps are deactivated, meaning pump delivered what was asked for by ECU.

-There is perhaps some air entering the inlet system at idle, with supercharger in bypass?
Crankcase and its ventilation status is shared amongst both banks as well.
That is why I mentioned PCV valves. They seem to fail at a certain age. Giving unmetered air towards the throttle body, after the Mafs.
So more air than ECU thinks goes in, giving a lean mixture as per programmed ECU map.

Anyone has more or other insights to this?

About the noise..
I had a Direct-injector seal fail. It gave an actual combustion leak, but only at WOT..(Noise!!)
Do you have something similar? In that case things (metering systems confused) could be related perhaps.

 

I just changed my PCValve because of the mileage, the very rare puff of exhaust smoke, an a rare P0171 code. Its not that much of a positive flow, as the name states. The flow is in two directions, but slightly less one way. Not like the old ball bearing inside a sleeve. The code returned! Following the tube to the throttle body, I could see that when it went inside the body, there is play between the two. Enough for a leak. Will fix it soon.

 

I'd be looking around the throttle body - this is an issue with the 4.2 - I dunno about the 5.0 injun.

 

Follow the codes? You have a vacuum leak and this has nothing to do with any temperature sensor?
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Smoke machine!!!

 

With long term fuel banks at 25% you have a major vacuum leak. Broken or unconnected hose somewhere. Possibly the short and long term together should be around 10%.

 

S0 why did you change the MAFs if the car was running without a problem?