Hi all!

Im sort of new to this part of the forums, I mostly post on and read the Series 1, 2 and 3 forum.

So I've recently joined your ranks as a x300 owner as well, very excited to get involved here too.

On to my point, as per normal Jaguar behaviour my new (old, but new to me) x300 is making a disturbing sound from the engine. I'm pretty sure that it comes from the head. Now I should mention that I've had a pretty good look through the forum for info on the before asking

The sound is a high pitched violent click or cracking sound which is either just one crack or one with a couple of rapid lesser follow up cracks.

It happens when idling and when driving, it seems to increase in frequency when the engine is under load but not a massive amount, maybe once every couple of minutes when idling but maybe one every 30 or 40 seconds when driving.

Power doesn't seem to change when it happens and it doesn't seem to trigger anything else when it happens.

I'm thinking it could be detonation? The prior owner told me he used 91 (91 is low and 95 is high in New Zealand). So I have also put 91 in which could be causing it.

What do we think it is?

Follow up question, what is there to know about the timing in this model? I have read it has knock sensors.

Thanks in advance for the ensuing advice!

 

Hello and welcome to the X300 forums!

If you're putting 91--which I assume translates to 87 or 88 in North America-- and getting a sound like that, I would say that your knock sensor has had it, especially if the previous owner had used lower octane fuel frequently. What I would do is run the fuel tank to near empty and then fill up freshly with 95. You'll also see a nice performance boost doing that.

The noise you're describing definitely sounds like pinging, as anything else THAT noticeable that doesn't go away would likely be fatal to the engine. The only other thing I can think of that would also match this description is a massively leaking exhaust manifold, but you would certainly smell that... but seeing as how you're using low octane, and the fact that the knock sensors are known to go on these cars, I'd say pinging is a safe bet.

Let us know how it goes! I'm sure many people will chime in here too.

 

Thanks for the reply!

I'll do that, and see how it goes.
I'll look into those sensors too, hopefully they can be accessed easy enough for replacement.

I feel like it's pinging/detonation but any examples Iv heard of it on YouTube don't sound like this. They all seemed to ping repeatedly when the timing is too far out, In quick succession.

I just get one really loud ping every now and then. Maybe it's just when the knock sensing cant adjust timing enough to avoid it.

Hmm food for thought :P

Thanks again!

 

I am with Trevor on both counts.

The 3.2 is not known for cracking the exhaust manifolds, as the 4ltr does, but anything is possible.

The fuel use scares me a a tad. NZ should have octane booster available, try a bottle.

If it is pinging you do NOT want to punch a hole in a piston as they are not available.

 

Thanks Grant, I owe you a beer, I'd buy ya a box if you were local, you're always helping people out around here!

Ok so I got a price for the knock sensors, they are quite spendy. I've also booked her for a check up, gonna get the local jag outfit to look into it, I'll do the work my self.

I guess I'll get an octane booster and see if that suddenly makes a difference. If it does then it must be detonation.

 

Hello again, I have an update for any others that might have this trouble.

I used a octane booster and the problem has minimised, this to me shows that the knock sensors should still be good, as I only get a couple of pings at a time. They must be fixing the timing enough to fix it for a while. With the higher octane helping.

I have read that the crank shaft position sensor along with the knock sensors is the knock make up the knock detection system. I am starting to think that the crack shaft position sensor could be going bad and not supplying a correct reading for the ECU to adjust to fix the knocking.

I'll report back after the fuel change, hopefully with good news.

I'll next refill with high octane gas (96) to see if that is better then the 91 (with added octane booster. +7 Ron numbers).

 

Actually, in my opinion, this sounds more like an intermittently failing knock sensor. The crank position sensor tends to fail all at once (very annoying, I've heard) and leave you stranded! I suppose anything is possible, but I confidently predict that your knocking will go away with a full tank of high octane. If you are interested in using lower grades of fuel, it would be a good idea to replace the knock sensor, but you will see a diminish in fuel economy and performance.

 

This is all very strange to me. My XJ6 runs very smooth and I have always run regular gas, 87. Never heard one ping even when I punch it which is almost never. I have tried running 91 and cannot tell any difference even in mileage. What am I doing right?