Maybe too much gas... Cylinder wall wash down. Hope not, but sounds like it. Gas can flood the combustion chambers, washing the cylinder walls clean of oil, which in turn reduces compression in the chambers. Bottom line: Won't start.

If it doesn't start w/ new plugs, pull them out and put a half teaspoon of oil down into each cylinder. This increases the compression.

 

I had this on a 4.0 s-type, same engine but i've only ever had it when the engine is cold, I started it, drove it 10 feet to get it out of the way then switched it off, came to it 10 minutes later and flattened the battery trying to get it going.

I removed the plugs, left it overnight and it started fine next day.

If he was driving it then it cut out I doubt it's going to be a low compression related to flooding problem though it won't do any harm to try, have you have the blow by test done for the nikkasil bore problem,this causes starting problems due to low compression, early cars also have the throttle body problem where they just cut out at speed, do you know if the throttle body has been changed

 

Sorry about bringing this several year old thread back alive, but the problem was the key dis programmed it self, dealer charged around $300 to reprogram it and the car ran fine since then.

Hope this helps if anyone else has this problem.

 

Hope it didn't take 2 1/2 years!
Congrats!

 

Since I have never heard of this before perhaps you could add all the details surrounding a key 'dis programming' itself.

Inquiring minds want to know!

 

Better late than never.

 

That's so funny. I don't want to sound like I'm bragging, but I didn't realize this was a 2 year old thread. As I read further and further down the first page I was wondering if you had tried a different key. I was about to type in a response when I saw the age of the posts. I was thinking that maybe the chip in the other key was close enough to allow the car to start, but at some point it got moved far enough away that the anti-theft system couldn't detect it, so the anti-theft system wouldn't allow the car to restart.

Someone please correct me if I'm wrong, but I believe the anti-theft system only tries to detect the chip when you first start the car. Once it's running it's not going to stop because that would be unsafe. If the anti-theft system killed the engine when you were in the middle lane of a busy, 5-lane freeway, the manufacturer would be facing some huge lawsuits. So I bet you drove the car an hour, stopped for gas or something, and when you tried to restart it it wouldn't start. Am I right?

I wonder if the person/dealer you bought it from had the other key in their pocket and that's what allowed the car to start. Then they just forgot to give you the second key.

 

The chip in the key is 'read' by the Key Transponder Coil (a.k.a. Exciter Ring) on the ignition lock barrel when the key is inserted. The purpose is to confirm key to vehicle pairing. If they match, the car can be started.

These transponders were a regular fail on the early XJ40's. I haven't read of similar problems with X300 / XJ8 / XK8 but, from the description, it sounds like the coil failed rather than the chip in the key.

Graham

 

WOW!!! $300 to reprogram a key seems high to me. Had two of my spare keys reprogrammed recently at the local Jag dealership for $30 each which I thought was high... but obviously got a pretty good deal.

 

I paid £25 and thought it a bit high

 

It may not feel like it but you got off lightly.

The last key I purchased for an XK8 was five years ago. It came from Jaguar overnight (precut) and was programmed at the dealer. Total cost £70.

The first question I asked when viewing my current vehicle was 'does it have 2 black headed keys + 2 remotes + 1 green headed valet key?' At dealer costs (in the UK), it's around £500 for a set of keys and remotes.

Graham

 

I was thinking like Sam. I didn't check the date, but after several posts i was thinking "security" issue. I had the same problem with a Sable my wife used to drive, and several times with my old ZR-1 (notorious for non-starts). That ign key can cause real grief because nothing gives you an indication of what's wrong. And, as we all know, a low battery will give all kinds of misleading symptoms, too.

 

Wow, I wouldn't have thought of the key in a hundred years.

Agree, it would be decent if the system had supplied a hint.