Hi, I have an unusual fault that causes my car (2007 vogue se 3.6 tdv8) to go into limp mode, only when either going up a very steep hill (holds the gear and doesn't drop down to help keep going up) OR when on the straight and needing more power to over take for example, usually around 30mph - 50mph or when just flooring it from take off, but this is intermittent and if the car is already at speed its fine. It feels as though its only when needing that extra boost or gear change to help with the power load.

Only fault code that comes up is p023d (22). NOW here's the unusual thing that even the LR tech and indies can't understand. When it goes into engine fault mode, I stick it in neutral and whilst rolling, turn the key once off and on again, bang it back in D and then the car will carry on all the way to Scotland, tackling any hill, without the fault happening again. Only once I park up and switch off the car, remove the key and then if taking back on a new journey, it will happen again. Intermittent.

I have checked all the associated diagnostics with that fault code and now have no where else to turn.

The car has had:
* new turbos
* all new boost hoses
* new inlet manifold
* new map and maf sensors
* sensor readings all correct
* high pressure smoke tests
* ecu flashed at dealers
* egr blanked
* no oil leaks
* gearbox oil changed
* vacuum pipes checked
* vacuum solenoid changed ( this was the only time it made a difference to the car, it was dropping a gear down when going up hill or needing more speed to overtake but for only 6hrs then the same happened again )

Anyone, help will be very very much appreciated. Thanks for reading.

the code is an indication of sensor failure. you state that the MAP & MAF's have all been replaced. Were they replaced with genuine LR parts or were they OEM made by Bosh or one of the OEM mfr's?

I have gone down the road of pattern sensors before that are half the cost and it has never ended well.

If you have the original sensors still unless they were clearly end of life or broken i would swap them over and see if this fixes the issues or at least rules them out. 2012 Vogue 4.4 TDV8 - Current
2014 Navara V6 - Gone
2004 Vogue TD6 - Gone
Grand Cherokee - Gone
Discovery V8 (LPG) - Gone
Discovery TD5 - Gone

iid tool or any other which can draw graphs will be helpfull. Draw the sensors values and turbo valves, and try to find when it goes wrong and what parameter fails first.

Swap MAPT and MAF sensors left and right to see if the fault swaps sides.

You stated that an inlet manifold was replaced so the other could be split although a decent smoke test would probably show-up a split.

My brother's MY08 3.6 RRS had the same fault code which was due to a split left manifold (when sitting in the vehicle). For a couple of years he also would restart part-way up hills with his van in tow to overcome the fault.

Jayk69 wrote:

the code is an indication of sensor failure. you state that the MAP & MAF's have all been replaced. Were they replaced with genuine LR parts or were they OEM made by Bosh or one of the OEM mfr's?

I have gone down the road of pattern sensors before that are half the cost and it has never ended well.

If you have the original sensors still unless they were clearly end of life or broken i would swap them over and see if this fixes the issues or at least rules them out.

jimmie wrote:

iid tool or any other which can draw graphs will be helpfull. Draw the sensors values and turbo valves, and try to find when it goes wrong and what parameter fails first.

GraemeS wrote:

Swap MAPT and MAF sensors left and right to see if the fault swaps sides.

You stated that an inlet manifold was replaced so the other could be split although a decent smoke test would probably show-up a split.

My brother's MY08 3.6 RRS had the same fault code which was due to a split left manifold (when sitting in the vehicle). For a couple of years he also would restart part-way up hills with his van in tow to overcome the fault.

Could be caused by sticky turbo actuator linkages.

Hi Graeme, there were both checked over by tech and said they moved freely, also had drivers side oiled recently whilst car went in for front linkage arm, aparantly n/s is harder to get too. But with the fault code throwing up an A side sensor which would indicate a fault on drivers side on rhd car, I thought best to get it oiled.

Also if it was acuators causing the fault, would a acuator fault code not come up and how would turning the key on/off explain the car not experiencing the same fault for the rest of that journey? The fault was still there the day the turbos were done.

Thanks

Has anyone measured the actuator commanded position & current, ideally with a scope? there are specific waveforms to look for if the actuator control detects a potential jam and runs an 'unstick' routine - there are no DTC's set by this process, only by a failure to achieve required boost. Even if the actuator & arm are 'free' then it's possible the turbo vanes and gimballs are sticking or causing excessive current draw under certain load / temperature conditions.

Hi Phoenix, the turbos are new. And the actuators have been ruled out by the turbo specialist, now they didn't charge me and could have billed me just to strip them down to get them out and I would not have been the wiser, so that's why I think it's definitely not actuator related.

However you stated " or causing excessive current draw under certain load / temperature conditions." Can you explain this please. Happens in when engine is cold or hot.

The fault happens when the gear is not changing down, when it should under load or when needing more power, as soon as foot is down, it goes limp. So could be restricted due to excessive current to stop further damage when second turbo kicks in?? But again not sure what that has to do with it not shifting a gear down when going up hill or when overtaking and needing instant boost.

Thanks

I'm not saying the actuators are potentially the issue, they may be drawing excessive current due to the vanes / gimballs in the turbo not moving under specific conditions. Just looking at the actuators & link rods is confining the inspection & testing to only half of the mechanism, although you say 'hot or cold', obviously the turbo will warm up pretty quickly with hot exhaust gases and friction. sdo in reality it's 'hot or hotter'.

It is purely a guess, it does sound to me like something is initially binding and the only moving parts are in the turbo(s) so that would be where I would look for heat related expansion or wear, it's possible that reused components in the turbo are out of spec or marginal and causing the initial 'hurdle' to be overcome, somehow easing the resistance until the engine is well cooled.

Gearchanges will only happen if the torque map is being achieved, if it isn't (and there are many torque maps for different circumstances / sensor input ranges etc.) then the transmission behaviour will not be as expected, it does sound though that is a symptom, not a cause.

Is the vehicle using standard mapping or has it been adjusted (remapped)?

Hi Phoenix, you make some good points.

The ecu was remapped and was recently flashed by LR tech to standard and still not made any difference.

In regards to gear change, I agree with you, in that it's not a cause.

Not sure what to do with Turbos because fault came back after a 15min drive after they had both been changed so underlying issue was elsewhere.

Out off all the parts that have been changed so far, the only two that made a difference to the car for only less than 24hrs was when I first changed both mafs, the car drove like a brand new car and then when I changed a vacuum solenoid, the car changed gears as should do when tackling the steepest of hills and only went limp the next day when I was on the straight and tried overtaking.

Hope that may help.

Thanks again

That's a good point about the vacuum system - has it been thoroughly checked? I see a lot of turbo / EGR / control system faults that come down to vacuum leaks, defective valves / solenoids, even vacuum pumps. The brand I'm currently working for (not JLR!) has a lot of issues with oil ingress and contamination that manifests itself with DTC's pointing in entirely the wrong direction.
I'm not sure how that would fit with your defined error conditions but if the event is at all reproducible, I'd be putting a couple of vacuum transducers in the system and recording the depth of vacuum every 0.5s. If nothing else, it'd rule it out.
It'd also be good practice to check for contamination, too many people discount it as 'just a bit of oil / water / coolant' etc. but it can really mess with components and system behaviour.

Yeah, the vacuum system has been ruled out since.

Car has been checked for contamination and its all good on that front.

I did think the same as you about the fault code pointing in wrong direction but Literally no more ideas on what to do next.

Thanks for your replies so far.