Hi Guys,

I'm really struggling to solve a problem with this particular smokey Jaguar

2008 X Type 2.2d Auto with DPF(i think all the auto's come with DPF)

The DPF System/ Routine in the ECU is forcing the car to overfuel constantly because of a dodgy DPF EGT reading -40C well two of them pre & post DPF.

Symptom's

First of all the car has no error codes at all, even if i unplug both of the DPF EGT sensors there are no codes. Wierd.

The car will constantly produce's Blue! smoke, it is Not Oil burning i know that would be the first thing to suggest but basically if you unplug the MAF sensor, the car then goes into "default" fueling mode and ignores the EGT sensor reading of -40 degree's C and just fuels normally & the car runs fine other then maybe a bit less power, most importantly no smoke not blue not nothing its perfectly fine for miles, plug the MAF back in for 2minutes and drive and then there are just plumes of blue smoke all round the car everytime you stop and you can see it in the mirror on pull off too, it stinks like unburnt diesel.

So what i think i've worked out is the way the DPF works, ECU provides more fuel because the DPF needs to be at high temperature to work as it should, so when the MAF is plugged in and the ECU see's Pre & Post DPF EGT sensors @ -40*C it adds diesel via injectors in an attempt to heat up the DPF....Constantly! Blue smoke everywhere.

Things i've done/tested in an attempt to resolve this issue,

all four injectors tested and coded correctly to ECU, we did this before realising the -40 EGT readings and when maf unplugged all smoke goes away.


Using Snap ON diagnostics i can view live data of ECU,

i have located both the sensors listed as EGT1 & EGT2 on snap on,

5v at both sensors
tested various resistors across the two terminals and the readings for both EGT Sensors will range from -40*C to -36*C and that's as high as it goes which is weird.

sensor/s unplugged or plugged in reads -40
330ohm =-39
270ohm =-38
120ohm =-37
56ohm and lower=-36

i managed to get acces to a Ford spares place (new DPF with sensors is £850) and had box full of these DPF EGT sensors i must have tried 8 or 9 that all fit and look exactly the same as original ones and every single one of them read -40C on live data
i also tried a 1k potentiometer it ranged from -40 to -36
i am almost 100% certain it's not the sensors due to resistors not managing to achieve anything better then -36

also i have noted that the sensors in the car will read -39 after the cars has been on a long drive as if the are working but something is stopping them reading correctly.

ok so i had voltage and could make the reading change on both sensors so i assumed wiring ok and sensors ok must be ECU.

i then ordered an ECU complete set because i could not find my part number online, ( 9x43-12a650-ab ) anyway the set i bought with key bodycontrol module and clocks, worked perfectly fine no smoke again accept the set was off a manual 2.2d X Type, i didn't know that though.

This ECU must have been from model with no DPF either as there were no EGT sensors listed on live data with the same Snap on Diagnostic machine, so car drove with no smoke with MAF plugged in no ECU error codes, but gearbox ECU has a torque signal error DTC so doesn't change as and when it should. and slightly down on power, anyway that was 2 weeks ago....

i've now bought a spare 9x43-12a650-ab ECU plugged it in as it was just to see if readings were any different , car won't start as i haven't programmed it yet, i can do this via BDM but no point as it does exactly the same as the original ECU on live data so that's just an unopened spare i have now and i already have BDM backup of original....

I'm almost running out of idea's and really do not know what else i can try but i do have a friend with JLR SSD software due at some point this week, i honestly don't think the dealer diagnostic tool will make a difference unless there's software update for such a problem, but i have searched everywhere for something remotely similar and nothing

If anyone has an ECU pinout diagram that would pretty helpful as one thing i have noticed and don't understand, the terminal's i use to power ECU on the bench, (i've attached a pic) are present in the ECU loom in the car but they do not produce 12 volts as i would have expected, ive traced them all the way back to the engine bay fusebox but it looks like those wires connect to a "hidden" relay inside said fusebox....i really am clutching at straws lol

Please help

Many thanks too anyone that takes the time to read this and for any replies in advance

Mark.

 

I thought i should also mention,

I know the original ECU has not been re-mapped, well i found that out first by comparing against other known original 2.2d auto files. I have also found out that this particular ECU Delphi with MPC555 and flash is really hard to remove DPF via Remap, anyway i have tried a file that was supposed to be DPF off but it disables cruise control and well the gearbox entirely lol can't get it out of park so went back to original backup read, if anyone knows of or has a 2.2 auto with DPF removed and no smoke please let me know who did the remapping lol

Mark.

 

Can't you just fix the EGT(s)?

 

Hi mate i would rather leave the car stock then mapped, so yes my aim is to resolve the EGT sensor issue, however i'm almost certain they are not at fault, simply because i have tried 8 spare sensors and mulitiple resistors to get a different reading, An EGT sensor is simply a variable resistor activated by heat.

the lowest the system can read is -40

i found a list of EGT related sensor DTC trouble codes pic attached and i have none of them listed on Diagnostic scan so something else seems to be causing my issue any suggestions much appreciated.

i should at the very least be getting open circuit when either of the sensors are unplugged and i do not it is really baffling me....i am starting to think it is missing that 12v supply on the ECU (mentioned at the bottom of first post) as i haven't got much else to go on at the minute.

i could do with a full pinout diagram so i know what i should be getting in the car loom.

 

Other cars are not hitting this so it's something about your car. Wiring / fuse / relay / whatever. Can't be rocket science to pin down.

 

Just thought i'd update on what the fix was and mistakes i made on the way lol,

Mistakes...

Trusting the snap on diagnostic and chasing a red herring....turns out there was nothing wrong with the DPF temp sensors, after confirming they were working correctly with JLR SSD software, the Snap-On tool just does not read them correctly ffs!


The Fix/ Fix's

So first off i wasn't getting error messages when i disconnected the temp sensor's which i found wierd i can't say 100% if this did it but the car had always had an error message saying Service required, this is connected to the dpf system, if the dpf has attempted regen for long enough the system knows the oil will have been diluted with fuel, i reset service indicator and i then started to get dpf fault codes appearing.

This then led to incorrect messages telling me the dpf was full when i know it wasn't.

Ok so the missing voltage i mentioned in the first post got me looking at the wiring and fuses again i managed to get hold of a full wiring diagram for ecu, this lead me to find underneath the main engine bay fusebox and concealed behind a plastic cover some large fuses, one of which the biggest one a 150A Mega fuse was blown, the only symptoms of this blown fuse which would have blown at least a year ago when a battery exploded on this vehicle, was the dpf random error's and smoke with no codes most of the time.

Changed this fuse all problems gone away Happy days.

Mark.

 

Hi mate I just bought a x type 2.2 and when i lift it on the elevator i notcied that the exhaust temp sensors are broken .. any idea where to buy them from ?? Already tried local parts shops and Ebay and Amazon... no luck there .. both of them broken ffs

 

Or if I could have a Part Number so I can look for the egt it would be awesome as the only ones that I can find are for XK / XJ 3.0 diesel any ideas??? I'm quite frustrated....