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It would be interesting to see if these readings, MAF etc. move about with the rough idle. I would have a really good look at all of the sensor readings, making notes of values, then try to find out what they should be. A really good long run may improve things.
 

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Discussion Starter · #25 ·
Update

I have replaced both MAF sensors and the oil separator aswell. The car now idled correctly so far touch wood. How ever since changing the MAF sensors it seems to have a boost issue. The car boost fine up to 22psi up to 2500-3000rpm then drops off to 15psi then returns to 22psi for the rest of the rev range.

Any ideas?

James
 

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Update

I have replaced both MAF sensors and the oil separator aswell. The car now idled correctly so far touch wood. How ever since changing the MAF sensors it seems to have a boost issue. The car boost fine up to 22psi up to 2500-3000rpm then drops off to 15psi then returns to 22psi for the rest of the rev range.

Any ideas?

James
That’s when secondary turbo kicks in. I guess you bypass valve actuator is out of sync which also could be caused by secondary turbo shutoff valve or primary turbo not delivering enough boost.
With engine warmmed up give it some throttle see if it helps. If iCarsoft have the functionality to recalibrate air induction actuators, try it.
I guess 22psi is calculated boost( actual measurement - barometric pressure)? Otherwise it’s a bit low.

check how the second MAF reading correlates to this drop in boost. There is a motored actuator on the turbo bypass valve that releases the boost pressure to the intake of primary turbo momentarily to help secondary turbo buildup revs. Check if the pipes going to that valve are correctly installed and have no leakage.

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Discussion Starter · #28 ·
That’s when secondary turbo kicks in. I guess you bypass valve actuator is out of sync which also could be caused by secondary turbo shutoff valve or primary turbo not delivering enough boost.
With engine warmmed up give it some throttle see if it helps. If iCarsoft have the functionality to recalibrate air induction actuators, try it.
I guess 22psi is calculated boost( actual measurement - barometric pressure)? Otherwise it’s a bit low.

check how the second MAF reading correlates to this drop in boost. There is a motored actuator on the turbo bypass valve that releases the boost pressure to the intake of primary turbo momentarily to help secondary turbo buildup revs. Check if the pipes going to that valve are correctly installed and have no leakage.

View attachment 193022
It does sound like it could be one of the actuators. I will give it a try recalibrating the induction actuators.
I have noticed aswell that at idle I either get 1psi boost or 0.50 is vacume.
I'm gather this would be down to these actuators?

See attached live date
 

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It does sound like it could be one of the actuators. I will give it a try recalibrating the induction actuators.
I have noticed aswell that at idle I either get 1psi boost or 0.50 is vacume.
I'm gather this would be down to these actuators?

See attached live date
Vacuum sounds a bit wierd. Diesels won’t go negative at idle. However, SDD shows the raw boost and its icarsoft calculations which could be in incorrect a little due to considering a different barometric pressure for calculation. Some use the one that is inside ECU package and some use the figure immediately before stating the engine.
the changes you mentioned is normal though. Every few minute the intake pressure will increase purposely by around 7psi (this is my experience, don’t have a reference for the exact figure). This is is done by adjusting the egr openings and vane angles of primary turbo. The pipe next to the temperature sensor that you replaced goes to secondary turbo and that extra boost is used to spin the secondary turbo for lubrication at idle.
Could you see MAF A and MAF B separately instead of their sum? That is more useful for diagnosis because you can see when each turbo kicks in and if there is any issues with actuators.
 

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Discussion Starter · #30 ·
Vacuum sounds a bit wierd. Diesels won’t go negative at idle. However, SDD shows the raw boost and its icarsoft calculations which could be in incorrect a little due to considering a different barometric pressure for calculation. Some use the one that is inside ECU package and some use the figure immediately before stating the engine.
the changes you mentioned is normal though. Every few minute the intake pressure will increase purposely by around 7psi (this is my experience, don’t have a reference for the exact figure). This is is done by adjusting the egr openings and vane angles of primary turbo. The pipe next to the temperature sensor that you replaced goes to secondary turbo and that extra boost is used to spin the secondary turbo for lubrication at idle.
Could you see MAF A and MAF B separately instead of their sum? That is more useful for diagnosis because you can see when each turbo kicks in and if there is any issues with actuators.

I can get separate maf readings on Icarsoft. I will have to get some readings and get back to you on that. I did have a look the other day and the second Maf was showing 0 until the vehicle got to 2500 - 3000 rpm which I believe is what it's supposed to do.

There has always what seemed abit of a flat spot but now that Maf's are changed its deffinatly more noticeable. The car does feel more powerful. It's just very annoying one problem after another.
 

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Discussion Starter · #31 ·
Vacuum sounds a bit wierd. Diesels won’t go negative at idle. However, SDD shows the raw boost and its icarsoft calculations which could be in incorrect a little due to considering a different barometric pressure for calculation. Some use the one that is inside ECU package and some use the figure immediately before stating the engine.
the changes you mentioned is normal though. Every few minute the intake pressure will increase purposely by around 7psi (this is my experience, don’t have a reference for the exact figure). This is is done by adjusting the egr openings and vane angles of primary turbo. The pipe next to the temperature sensor that you replaced goes to secondary turbo and that extra boost is used to spin the secondary turbo for lubrication at idle.
Could you see MAF A and MAF B separately instead of their sum? That is more useful for diagnosis because you can see when each turbo kicks in and if there is any issues with actuators.

I have attached readings of both MAF sensors individually at different RPM.

I have noticed then when sitting on the dual carriageway at 70mph the rpm keeps fluctuating constantly by 200rpm either way. Also dpf light has come back on within 100miles of last regen. This has now cleared again though. I gather this is caused by this fault.

Please let me know your thoughts
 

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I have attached readings of both MAF sensors individually at different RPM.

I have noticed then when sitting on the dual carriageway at 70mph the rpm keeps fluctuating constantly by 200rpm either way. Also dpf light has come back on within 100miles of last regen. This has now cleared again though. I gather this is caused by this fault.

Please let me know your thoughts
In these photos the MAF 1 that goes to secondary turbo is reading almost 0 all day time. The secondary turbo is Not kicking in at all.
If possible try to read the MAF readings on the move. I remember once I floored the throttle momentarily and sum of both MAFs was around 350gr/s. If you are confident about MAFs and don’t need to swap them to test, sounds like your secondary turbo shutoff valve does not operate. That’s the one behind the turbo. It operates on a vacuum line and solenoid is somewhere on top left hand side (if memory serves).

keep an eye on MAF bank 1 and see if it goes higher than 10000g/h in any situation. If it does, turbo bypass valve is blocking it. If that stays below 10000g/h all the time, turbo shutoff valve is not operating.

below is the solenoid that operates the valve. Try to bypass the solenoid and open it to see if it would kick in.

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do you remember the soot levels when dpf regen ended on last time? What engine oil are you currently using? I once used a petrol graded oil in my car by mistake and dpf was full every 200miles.
 

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Discussion Starter · #33 ·
In these photos the MAF 1 that goes to secondary turbo is reading almost 0 all day time. The secondary turbo is Not kicking in at all.
If possible try to read the MAF readings on the move. I remember once I floored the throttle momentarily and sum of both MAFs was around 350gr/s. If you are confident about MAFs and don’t need to swap them to test, sounds like your secondary turbo shutoff valve does not operate. That’s the one behind the turbo. It operates on a vacuum line and solenoid is somewhere on top left hand side (if memory serves).

keep an eye on MAF bank 1 and see if it goes higher than 10000g/h in any situation. If it does, turbo bypass valve is blocking it. If that stays below 10000g/h all the time, turbo shutoff valve is not operating.

below is the solenoid that operates the valve. Try to bypass the solenoid and open it to see if it would kick in.

View attachment 193062

do you remember the soot levels when dpf regen ended on last time? What engine oil are you currently using? I once used a petrol graded oil in my car by mistake and dpf was full every 200miles.

Thanks for getting back to me

The max both mafs combined is hitting is around 280 g/s which is obviously alot lower than the 350 g/s you got on full load.

I have had a look at maf readings while driving and bank 1 does go way above 10000g/h at low rpms it hits around 5000 to 8000g/h and alot higher in higher rpms 20000 plus

The maf sensors are both brand new so I'm pretty sure they are reading correctly. Do you think Its the solenoid valve causing the issue ?


As for dpf oil I used was c1 grade which I believe is correct?
 

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Thanks for getting back to me

The max both mafs combined is hitting is around 280 g/s which is obviously alot lower than the 350 g/s you got on full load.

I have had a look at maf readings while driving and bank 1 does go way above 10000g/h at low rpms it hits around 5000 to 8000g/h and alot higher in higher rpms 20000 plus

The maf sensors are both brand new so I'm pretty sure they are reading correctly. Do you think Its the solenoid valve causing the issue ?


As for dpf oil I used was c1 grade which I believe is correct?
20000gr/h= 20000/3600=5gr/s which is next to nothing. Secondary turbo would use in excess of 160gr/s that is 576000g/h.
However this means probably the turbo shutoff valve does open and bypass valve is not letting the pressure to get to inlet manifold. Have you tried to manually operate the bypass valve actuator?is it free to move by hand?

C1 is correct.If it happens again maybe exhaust pressure sensor or the hose to sensors are at fault.
 

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Discussion Starter · #35 ·
20000gr/h= 20000/3660=5gr/s which is next to nothing. However this means probably the turbo shutoff valve does open and bypass valve is not letting the pressure to get to inlet manifold. Have you tried to manually operate the bypass valve actuator?is it free to move by hand?

C1 is correct.If it happens again maybe exhaust pressure sensor or the hose to sensors are at fault.
I have tried moving the bypass valves on the left and right hand side of the engine and these move freely. Or do you mean the one at the front of the engine?


I just tried by passing the solenoid and it was still the same to drive but went into limp mode above 3k rpm which is to be expected.
 

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I have tried moving the bypass valves on the left and right hand side of the engine and these move freely. Or do you mean the one at the front of the engine?


I just tried by passing the solenoid and it was still the same to drive but went into limp mode above 3k rpm which is to be expected.
Those on left and right are actuators for EGR cooling bypass valve. The turbo bypass valve is under the car, between radiator and engine.
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Discussion Starter · #38 ·
Those on left and right are actuators for EGR cooling bypass valve. The turbo bypass valve is under the car, between radiator and engine.
View attachment 193077
No 5

I will test tommorow to see if it moves freely. Il take of the shut off valve also and see what condition its in. Just out of curiosity what boost pressure should I be getting if everything was working properly?
 

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I will test tommorow to see if it moves freely. Il take of the shut off valve also and see what condition its in. Just out of curiosity what boost pressure should I be getting if everything was working properly?
I guess you mean the bypass valve? It’s relatively easy to take off.
Shutoff valve is behind the turbo and hard to reach.

before taking anything apart, If you have help, you could keep manually operate the bypass actuator arm to see if boost will pick up at engine speeds above 2800rpm or at least watch it to see if it operates.
Not far from what you get. The standard engines probably get to 24psi calculated boost or 34psi raw. S models get to 27-29 psi calculated or 38-40 psi raw.
However, I recon the 22psi you get is not very bad but it won’t keep up with the air flow that is required and pressure drops.
On the other hand, if you consider the 4-5psi more boost is making 35 more horse power, you probably are loosing 18hp minimum at 22psi or 66hp at 15psi boost.

I forgot to mention, there is a second air pressure sensor that reads the output of seconary turbo. In SDD it is called boost pressure sensor or measured boost pressure or something like that. If you could find it, it should read barometric pressure before secondary turbo kicks in and then follows the MAP sensor reading. The sensor is mounted under the steering pump and on top of alternator. That could give a good clue as well if secondary turbo is engaging at all.
I forgot to ask. Does your car show any warning or check engine light when this problem happens?
I guess not?
 

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Discussion Starter · #40 ·
I guess you mean the bypass valve? It’s relatively easy to take off.
Shutoff valve is behind the turbo and hard to reach.

before taking anything apart, If you have help, you could keep manually operate the bypass actuator arm to see if boost will pick up at engine speeds above 2800rpm or at least watch it to see if it operates.
Not far from what you get. The standard engines probably get to 24psi calculated boost or 34psi raw. S models get to 27-29 psi calculated or 38-40 psi raw.
However, I recon the 22psi you get is not very bad but it won’t keep up with the air flow that is required and pressure drops.
On the other hand, if you consider the 4-5psi more boost is making 35 more horse power, you probably are loosing 18hp minimum at 22psi or 66hp at 15psi boost.

I forgot to mention, there is a second air pressure sensor that reads the output of seconary turbo. In SDD it is called boost pressure sensor or measured boost pressure or something like that. If you could find it, it should read barometric pressure before secondary turbo kicks in and then follows the MAP sensor reading. The sensor is mounted under the steering pump and on top of alternator. That could give a good clue as well if secondary turbo is engaging at all.
I forgot to ask. Does your car show any warning or check engine light when this problem happens?
I guess not?

I Will investigate further and let you know how I get on.

No pending or permanent fault code stored which is making it even harder to pin point
 
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