No spark on XK8

[Mini]

I have a 99 XK8 that I bought from a previous owner as a non runner. The engine would start but quickly stall. The previous owner had bought a replacement ECU and cloned it and it got rid of many spurious codes inc Knock sensors. With the new ECU the codes cleared except for two Evap codes P0453, P0447 and a crank sensor P0336 circuit range code. The car has got steadily worse to the point it will now not start at all. I Have changed the crank sensor but no change. I have continuity from the sensor pins to the ECU pins.

The fuel pump is working and showing 40PSI at the shraeder value plus I can smell unburnt fuel coming out of the exhaust. I am getting between 4-5 volts on one of the 4 pins on the coil packs. The battery is new and well charged but I can't get a spark on any of the plugs.

I have followed the cylinder wash clear procedures (clean plugs put oil in cylinders) as I thought that might be my issue but still nothing.

The version is the newer version for ignition and it does not have the 2 ignition modules like older ones as I understand the ECU does all of that.

Putting the old ECU back in does not fix it either.

I have now spent hours on this and don't know where to go from here except to scrap the car.

Anyone help me ?

Thanks

[mike020150]

Trying to solve problems after someone else has had a go can be extra difficult because you may not be aware of all the previous actions taken. Consequently, it pays to trust no information and to start from square one. In this instance, have you actually heard the engine running or did you take it on trust that the engine did run briefly with all its current components (including both the old and new ECUs)? Cloning an ECU raises questions about the versions of software used and whether they are compatible with the hardware/wiring, e.g. 2-wire and 4-wire coil packs. Unless the original ECU has been physically damaged, it's probably the last suspect in the list of things to be checked. Hence, it's best to use the original and work through the other suspects first. For example, a failing fuel pump relay could allow an engine to start and then stall. Equally, if it fires and stops, the engine coolant temperature sensor may have been a simple culprit. If the engine turns but doesn't fire, the security system may be implicated and so on.

If you are using a generic code reader, particularly on an early XK8, you may not be getting all the available information stored in the system. To check would require either the appropriate Jaguar diagnostics or Autologic kit that Jaguar specialists use. Having tried a few things and run out of ideas, a hour's diagnosis might be able to point you in the right direction. Mike.

[Mini]

Thanks Mike

Yes the engine ran on both ECUs the same but it was difficult to start and it would not tolerate much throttle. It got harder and harder to start then stopped completely. The only difference the new ECU is as that it didn’t have as many fault codes on it.

Before I splash out someone suggested the car might think it Immobilized. Does crank and fuel still work if bring immobilised ?

Any last ideas before I take the plunge ?

Thanks

[JimMann]

Hi Mini, in "the good old days", 3 things were required for an engine to run. Compression, fuel and spark. It sounds like you have the compression and the fuel feed, so the spark is missing. Unfortunately on a modern engine, there are so many sensors that need to confirm their presence and happiness to the ECU before the spark is "released", that it is now so much more difficult to fault find why the spark is not present.

As Mike has indicated, an approved diagnostic check on all and any of the codes would be a start, but then it is a case of working "methodically" through the faults to determine what brings the spark back into the motor.

Not much help I appreciate, but stick with it.

Jim Mann

[Mini]

Should I buy a mongoose cable and IDS v130 to get the crucial data ? Would icarsoft be as good ?

Thanks

[mike020150]

If the car did start previously, it doesn't sound like an immobiliser issue. As Jim says, that leaves 3 basics. Carrying out a compression test would tell you whether the engine has a fundamental (expensive) mechanical problem. 40psi in the fuel system is about right but is it there all the time? A failing fuel pump or fuel pump relay could result in weak mixtures and difficulties starting followed by stalling, similarly for the engine temperature sensor. Have you tested/replaced the sensor? Can you always hear the fuel pump running during each start attempt? Does the fuel pressure falter? Before suggesting replacing ignition components one by one, I would plump for a proper diagnostics session. DIY code readers are improving all the time but I'm not aware of any which are capable of reading the diagnostic codes fully rather than just those basic codes mandated by legislation. I would be more than happy for someone to prove me wrong on this last point! Mike.

[Mini]

Thanks for the replies.

I have moved on a little.

I had a blown fuse on the coils which takes me back to where I was when I bought the car in that it will start but often takes multiple attempts to get it going. Once going it runs unstable and putting any foot on the accelerator causes it to falter and stall.

On crank I have 40 PSI of fuel pressure but once started it is between 30-35 on a cheap ebay gauge.

Changing the ECU makes no difference and the codes I have are p1648 and P0336. I sometimes get P1648.

I am guessing the only one that would give the symptoms is the P0336. I have changed the sensor and continuity back to the ECU. Could this be a failure if the relucter ring ? Any way to tell without removing the gearbox ?

Thanks