Can you swap out the ECM plug and play ?
I have a 1999 XK8.
Its got the Jaguar " trot a lot" syndrome .....erratic idle,hi rpm and low rpm whilst driving.
Red and yellow lights,no traction control and then limp mode with no acceleration possibility.
Temporary fix is to stop shut down,wait 10 sec with the key removed.
Then start up all lights go out and try to head for the barn before the "trot a lot" starts all over again !
Decided that its the ECM thats bad.
Will change that out next week when it arrives from ebay.
Driving around in my trusted Land Rover for this week.(this one is not equipped with "Lucas the price of darkness"
Any tips on changing out the ECM ?
Thanks.

 

Another possibility is a throttle body/TPS problem.

What does the car think is wrong? Do you have any codes thrown? If so, post them here:- the actual codes, not any interpretation of them.

 

+1

My first thought would be TPS before ECM.

Graham

 

+ 2 and get the codes read.

 

Hi Guys,
Thanks for the tips,
You asked for the codes:

P1143.
P1647
Traction Control fail
Stability Control fail
Failsafe Engine mode
ECU Communication fault
U 1261 SCP Circut Fail
Critical Transmission Failure.

Shut the old girl down,restarted shift to drive not manual shift and away we go......then redlight comes on again.....Traction control fail ,rough idle and Limited performance this time.
But the top still does go down,
10 miles later erratic rpm and then 3500 rpm with stall......no restart possible.
Thank god my wife left her huge sunglasses behind after the last trip,this gave me something to hide behind as i waited for the tow..........Yes a tow, my wife and my Land Rover to the rescue ! (i did not surrender her sunglasses,need them for the next breakdown)
After the winch party the Jaguar started again !

Once the ECM arrives will change that out,reflash and hope the old girl stops her **** before i lose my ****.

 

I would definitely concentrate on the ABS module instead. I would look at the "usual" power wire re-soldering on the main board, but also at the pins in the connector, etc. My understanding is that the ABS module provides the necessary terminating resistance for the CAN network. If the CAN bus is somehow compromised, then the ECU will have trouble communicating with the TCM.

Next, I would check the TSBs on jagrepair.com for everything related to the well-known instrument cluster problems. Never done it myself, but it looks like basic soldering is involved again.

Best of luck, keep us posted.

 

I see fmertz has responded while I was composing this, so I bow to his deeper understanding, and will throw it in anyway...

Here are the code translations from the AJ27 Engine Management – 1999 MY:




As always, it's worth following the hard reset procedure. There also seems to be a couple of random messages, so is the battery good - i.e. at-rest voltage greater than ~12.4V?

The P1143 is in the TB area so I would investigate that as a starting point.

You can check the B bank HO2S heater state by measuring resistance across the Purple/Slate and White/Green connections.This thread from RaceDiagnostics may help:
https://www.jaguarforums.com/forum/x...72/#post837299

 

Hi Guys,
I unplugged the ABS harness as suggested by F Mertz.
The plug looks clean,but i sprayed contact cleaner on the contacts just to be sure.
After doing a hard reset i then started up and the engine ran fine in cold condition (choke) then it started to run a bit erratic (warm) but nowhere near as bad as what it was.
Ran the code check again, this time got limited performance (yellow) only.
Code is now 0327 bank 1 and o2 heated sensor (sensor is a normal fault if the engine runs out f spec)
So it seems that i,m making progress.
Will keep you guys posted.
Thanks once again to F Mertz for the kick in the right direction !

 

Well i,m at a loss what to do with my Jaguar,
Cleared all the codes cleaned out the ABS connectors ,now got a limited performance check light .
Took my OHM meter to the knock sensor still has 0.8 ohm so its good,dont know why its getting a code.
Swapped out the sensor with a new sensor and still the same result,limited performance.
After shutting down the engine,i restarted and the warning lights went out.
Got no idea where to go from here.
The engine still runs erratic but a lot less than before.
Next stop is ECM swap out and re-program the new ECM.
If that fails i will rip out the injection and stick on a aftermarket system and run the engine stand alone.
Will keep you posted.

 

Please can you clarify if it is the knock or the HO2 sensor which you replaced. ~0.8Ω would be in the region for the latter.



Are you still getting the P1143?
Is the battery up to scratch?

I'm not convinced the ECM is the root cause here. You will find the stand-alone ECM route will bring its own challenges (cost + the motor and trans talk to each other)

 

Before you replace the ECM, much of this behavior, especially the CAN and SCP behavior sounds like wires. The ABS is connected to the ECM, TCM and INST. Connector cleaner can potentially improve the other three too at almost no cost. ECM and TCM are easy to get to (in the same box on the right side of the engine). INST is only a bit more difficult, but I'd make sure the contacts were clean before moving forward with the ECM replacement. If that does not improve things, it's fairly straightforward to take the INST out (and replace the bulbs while in there). Soldering the contacts as fmertz referred to above is straightforward if you've ever handled a soldering iron, did it in a few minutes (if not, it's still pretty simple, happy to help).

There is a fifth module hanging off the CAN bus in the gear shift module (gear shift illumination module) which has dotty solder connections at the edge of the board. Slightly more involved to get there (console has to come off), but could be an issue and is also simple to resolder.

Overall point. If the CAN bus is not whole (intermittent wiring issues, for example), the transmission, instrumentation module, security module, etc will not communicate properly and can throw spurious codes.

Also, if you've been disconnecting the battery, are you doing the reset procedure?

https://www.jaguarforums.com/forum/a...connection-pdf

If you don't do this, the engine can run like crap for a while while the ecm relearns without the initial 'teaching' step.

 

The replacement ECM will require an 'Immobilization setup'.
The CAN bus will not recognize the replacement ECM without this step.

Dealer level diagnostic equipment is needed to perform the immo-setup.

bob

 

I purchased a new ECM from Foreign Auto Computer Repair. You send them your ECM and they reprogram the new one with your immobilization codes. That worked fine.

 

Hi Guys,
Thanks again for the tips.
I took my XK8 on a very long road trip.
During a rain shower the car went into safe mode several times,i would stop shut down and then restart no problems.
As soon as i got to the south 800 miles away from New Hampshire the engine safe mode stopped,now it accelerates after hitting a bump in the road.
It still idles like a cow so i think its a TPS issue.
The 4 wires do not clip in to the receptor ,so i will clean with contact spray and do a reset.
On the bright side it cant be a ECM because i get good mileage,503 miles range and 27.2 MPG average according to the trip computer.
I drove the XK8 for 2135 miles in two days,the old girl had blisters on her tire,s !
Now the clock is on 140200 miles total.
Will keep you posted on this deal.

 

Back on the search again for the issues.
I ordered a new TPS from the well known ebay system.
Jaguar is in Florida,i,m in NH.
Will fly down next week and replace the TPS,
Vehicle battery is new.
Will keep you updated

 

Got the sensor out and exchanged with new one,took me 10 min.
No codes anymore,just the usual heated O2 sensor bank 2.....this is due t the TPS out of service.
The battery is new and good.
Ordered a new TPS from the ebay.
Flying down next week to fix Jaguar .....( hope the TPS is the culprit!)
Will keep you guys posted

 

Jaguarfriend,

I’m following your thread with interest. Your persistence is admirable. Keep at it!

 

Changed out the sensor on the TB,no go same problem.
Took some Quick Start and sprayed the inlet manifold at the connectors Manifold/Engine.
Gt a rise in RPM so its a bad Manifold/or seals.
Will fly down again to get a new Manifold on the old girl.
Will keep you posted,even though the interest has faded.

 

If the leak is that obvious, you might want to to a smoke test and find all the leaks. There are so many possible spots for air leaks you might as well try and find them all. Removing the intake is not as simple a job as it seems (it is more long and tedious rather than complex). Opens the possibility of other jobs, too, like the valley hoses.

For the smoke test, you can have it done, buy a smoke machine, or even make one with an old soldering iron in a jar and a bicycle pump...

 

Well guys here is my short update.
Did a smoke test,and smoke came out all over the place.
Ordered a used intake on ebay,and as expected it was the wrong one!
Sending it back will cost more than i payed for it.
Ordered another one this one was right for a change.
After a 6 hour job swapped out the evil part for a less evil part.
The jag started up good and runs fine just throws the "Limited Performance" trick at me!
Looked into the computer,it shows TB error.
Ordered a new knock off TPS and yes you guest it right, wrong part!
No end to the misery yet.
Waiting for the correct part.
More news next time.