XKR with weak spark? and failing to start. RESOLVED
 

Hi all, I was wondering if you might be able to help give me some pointers.

My 2001 Jaguar XKR is refusing to start. Prior to this it had always started perfectly and instantly without any hesitation.
I had been out for a short run, everything was fine. I parked up and gave it a wash. A few hours later I went to start it and despite it cranking over fine it refused to fire, even the slightest little bit.

The battery is fine and at full voltage. I have also tried a reset (disconnecting the battery and touching terminals).
The car cranks over fine.
Fuel pressure is great at the rail (about 45psi)
No diagnostics errors are showing up.

I removed several of the coil packs and checked them with spark plug. I was wondering if the spark is seems a little weak? Video of spark below.

If the spark is on the weak side, where would I need to start looking and at would I need to check?
On the other hand, if the spark is fine, then what else could be the cause?

Thanks in advance.

Under the hood, passengers side US, or as your in the UK drivers side under the bonnet. There is a black box. If you open it up there should be some brown relays in the shape of a T. One of those controls the starting. If you google it you should see what I mean. All the brown relays are the same so you can swap over the starter one just to see if its that.

I too had similar problems. You might find some ideas on here click me to read .

If you do, or even dont, solve it please let us know wont you? Thanks :)

https://cimg5.ibsrv.net/gimg/www.jag...ee208c75d7.jpgIgnore the red arrows. I borrowed the picture from somewhere else.

Hi sweatyfox,

The fact that you washed the car just prior to the onset of the no-start condition seems like a clue. Is is possible you got something important wet? For example, is there any sign of water in the footwells that could indicate the ECM may have gotten wet?

It would be worth opening various electrical connectors in the engine bay to check for water ingress, maybe starting with the crankshaft position sensor (CKPS). Also inspect both ends of the engine ground strap for corrosion since it is the ground path for spark from the plugs.

Your spark does appear weak, but it can be hard to tell in bright light. I note that your plugs have four ground electrodes instead of the single ground electrode of the OE NGKs. Perhaps your spark always looks that way?

Cheers,

Don

Now fixed and running! :icon_biggrin:

Hi all and thanks for your suggestions.
There was no water that I could find in the footwells, nor near any connectors or engine bay, everything was dry.
Today I checked the relays Frankc mentioned and I also checked the relays in the boot, tried lots of swapping but no luck.
I also got under the car and removed the earth strap, wasnt too bad but I cleaned it up anyway, but still nothing.

At this point I was getting pretty annoyed, so decided to check every electrical connection visible.
After a few minutes I popped off some covers and to my surprise I discovered a relay sitting proud and barely touching the contacts!
I pressed it back in, was a firm fit, decided to try the car thinking 'surely it cant be that saimple' and it started pefrectly!

I have no idea how a relay could pop out like that, but at least its fixed :D

Pics of the relay location attached.

Thanks all
https://cimg0.ibsrv.net/gimg/www.jag...dde4b875f6.jpg
https://cimg3.ibsrv.net/gimg/www.jag...8d42772780.jpg

Hi sweatyfox,

That's the Throttle Motor Power Relay. Very wierd that it popped out of its socket!

The relay to its left is the Fuel Injection Relay, and the one to its right is the Ignition Coil Relay. Together they are three of the most critical relays in the entire vehicle.

Glad you figured it out, and grateful that you reported back to let us know the resolution. I'm going to mark your thread RESOLVED.

The next time you replace the spark plugs you may want to try the OE NGKs to see if your spark improves.

Cheers,

Don