What could cause a sudden complete spark failure?

I started the car, it idled for perhaps 5 minutes, then suddenly went dead. It cranks as normal but not restart. Yes, there's fuel pressure (50+lbs), new CKP, good battery fully charged @12.5+ v, but no spark. New plugs and coils. Even with starter fluid, it does not even hiccup.

I've been working on fixing several issues with this 38k '04vdp following major work. I would start it, let it run while I checked codes and generally look it over. It does not run well, but would start reliably, if with some difficulty. Needs o2 sensors.

I've checked fuses and relays, but nothing yet. Previous codes:
p0182--fuel and air metering (new EFT sensor ordered) ;
p0506, low RPM idle
p0353, cylinder 3 coil fault (replaced).

Odd! Time to break out the electrical manual and dig in; just looking for some quick wisdom borne of experience.

marc

 

There are electronic relays which are integral with the PCB in the fuse boxes.

Not sure how to diagnose except change fuse box.

I assume it's the engine fuse box in this case but follow the wiring diagram backwards.

More ideas here:

http://www.jagrepair.com/JaguarXKXJSTypeNoStart.htm

 

Sorry missed the point where you had replaced the plugs, that was a lot of typing for no gain

 

Hi Marc,

I'm going to mull over your symptoms, but one quick test you can do to confirm no spark is to remove a coil, install one of your old spark plugs in the coil, reconnect the coil to its electrical connector, connect the threaded sleeve of the spark plug to ground with a jumper cable and position the plug so it won't melt any plastic components, crank the engine and watch for spark.

The coils receive their ignition-switched power via the Red/White wires from the Ignition Coil Relay (R7) and Fuse 30 (10A), both in the Front Power Distribution Fuse Box in the front right corner of the engine bay. They are grounded individually by the ECM. There is an Ignition Capacitor mounted somewhere at the center of the bulkhead - if it were to short internally, it would short the RW power to ground, but that should blow Fuse 30.

If the inertia switch had been triggered the fuel pump should be disabled. I don't know if the same is true if there is a problem with the immobilization system - I'd have to look that up.

There are separate camshaft position sensors (CMP) on each bank, but I suppose it's possible that if there was a problem with the Bank 1 CMP sensor the ECM might not be able to determine cylinder 1 TDC to establish ignition timing. But I would think this would trigger a DTC, and you don't show any related to the CMP.

What prompted you to change the CKPS, and is it possible the new one is bad (it wouldn't be the first time), or its electrical connector is loose or contaminated with oil?

Cheers,

Don

 

I forgot to mention that I did do the spark test (no spark), and was cranking it with a helper battery to ensure good voltage.

I swapped the R7 relay with another, and checked the fuel cutoff inertia switch. I have looked at every fuse a couple of times; still need to do some in-depth examination of the relays. (That electrical manual is great, but there's no easy way to identify the relays).

The only recent faults have been P0182, Fuel and Air metering, and P0335 misfire, plus the usual generic P1000. I replaced the fuel temperature sensor (never heard of one before!) as well. I have ordered a better OBD2 diagnostic unit, and am hoping for more intelligence from that.

The car came with a new crank position sensor in the trunk, along with new coils from a previous mechanic's attempt to make it run well. Naturally I have sprayed connectors with electrical contact cleaner.

Time to slog through that manual again and see if I can decipher some new intelligence. I know the answer is in there...somewhere!

 

Hi Marc,

In the Electrical Guide, the relay locations are given on the page before the wiring schematic, where all the components and locations are listed.


We may have a clue after all, if the code you've had in addition to P0182 is P0335 and not P0353 as you originally reported. P0335 indicates a problem with the circuit for the crankshaft position sensor (CKPS). Here's the listing from the DTC Summaries:



Given that the crank position sensor provides the primary signal to the ECM for ignition timing, that is still my first suspect. New ones don't always work, and oil contamination of the connector or damage to the wiring harness are possibilities.

It might be worth studying the wiring schematics to see if the circuits or harnesses for the CKPS and FTS have anything in common. It could be possible that the P0182 and P0335 codes have the same cause.

Cheers,

Don

 

Something that should be ruled out before digging too deep is the anti-theft system. Have you got a second key or any other chance to make sure that there is no glitch in this part?

I remember a friend who got stranded at the end of his vacation because his car didn't start anymore. After towing and 2 days of workshop checks it showed that the transponder in his key had been damged while it had dropped on a stone floor. Not sure if also "intermediate"damages are possible like in a loose electric connection.
Not the most likely solution, but certainly the easiest if found to be true.

 

Thanks for all the input.

After installing another new crank angle sensor, it still did not work. I pulled the wire to the sensor and checked the voltage. It showed a constant 2.5 volts, even while cranking. Should be 5 V when cranking; would expect 0 volts otherwise.

I've found a donor car that I hope still has some of the parts I need. I'm not opposed to parts-swapping just like the dealer service techs do!

Front fuse box? All fuse boxes? I'm getting impatient, which is not a good thing. This car is too pretty to just sit there.

 

Hmmmmm.......If it were me, I might consider disconnecting the electrical connector from any one of the ignition coils, and check to see if you have something like +12VDC on one of the two terminals (probably the red wire) of the electrical connector while the engine is cranking. For this test, you would want the negative lead of your voltmeter connected to a good earth ground. Be careful not to short the two terminals of the electrical connector together while performing this test.

If you indeed have voltage, then I should think that it would be a simple matter of connecting an analog meter to both terminals of the electrical connector to see if the voltage oscillates on & off while the engine is cranking. For this test, be careful not to short the two terminals of the electrical connector together nor your probe leads.

If the voltage does not fluctuate on & off, then it might lead me to suspect a defective ECM. Of course, this is assuming that all of the related inputs to the car computer are properly met.

 

Amphigory wrote: "I pulled the wire to the sensor and checked the voltage. It showed a constant 2.5 volts, even while cranking. Should be 5 V when cranking; would expect 0 volts otherwise".


That's not how one checks the crankshaft sensor. The ideal way is to hook up an oscilloscope to the plugged in leads while cranking the engine as the sensor will only output a square wave.