Hi All,

My XJS is suffering from classic crankshaft sensor failure (I'm assuming my model does have one...), essentially it runs for about 5 mins then cuts out and wont restart for 10 mins or so.

Car has a spark, fuel pressure good but no pulse to the rail.

I've spent a good hour now trying to find the little bugger but can't.

Could someone let me know where it is.

Thanks in advance.

 

Marrelli started with # 157116 (I think)

 

If your car has Lucas ignition, it does not have one.

Greg

 

Thanks, so would it be a timing or ECU issue?

Thanks

 

Does your car have 2 orange igniters on the radiator top support? if not it is Lucas not Marelli. If they are there then its Marelli and the crank sensor is on the front RH side slightly under the damper. easiest access is from under the car, there will also be a speed sensor on the flywheel

 

I reckon it is Lucas.

The "most common" for what you describe quite clearly is either:

1) The ign module INSIDE the ign amp (magic box) firmly bolted to the LH inlet manifold. The module is easily replaced. Being as you are in the UK, brands will vary. I use an Echlin (made in USA) brand, part number is TP45B (B = blister pack).

2) Also inside that amp is a condensor, that is well documented as leaking to earth, so simply remove it. No ill effects will happen to you or the car by doing so. I removed both mine many, many years ago, still sweet.

3) The coaxial (shielded) cable coming from the ign amp TO pin #18 of the ECU has a break in the THIN internal wire. Sooooo common. It will take some finding usually, but by simply running the engine and "fiddling" with the loom running across the rear of the engine may cause the engine to stop, or hiccup, you found it, simple now.

The list will be long if those items do not sort it.

 

OOPS, must read better as I get older.

I reckon its pointing at that this wire inside the coaxial wire.

Orrrr, the CTS (coolant temp sensor) on the LH thermostat rear housing is going flaky. Unplug it, bridge the terminals IN the plug, start the engine, see if it runs longer than before, if so, that sensor is #1. They are cheap, about $20, and fit many cars, including BMW, Merc, Ford, GM. I have the Bosch part number somewhere if you need it.

 

Many thanks chaps, I will have a look at the potential culprits and report back.

 

PS I replaced the IGN amp as my first port of call but to be fair it was second hand so may have the same issue.