I am hearing this rattle when accelerating. It sounds like two bottle caps clicking against each other (or maybe a tambourine) and it doesn't show up until the car has been driven for 7-10 mins. No codes. Seems to almost disappear when revving in neutral. I just put in new front tires and had them check for loose heat shields but they found none. I plan on taking it to Coventry Jaguar here in San Diego.

The sound is more pronounced when I blip the throttle (a true rattle). If I hold at about 50% it still rattles when accelerating but not as much as the initial blip.

Here is a clip of the sound. The rattle can be heard at the 0:10 second mark for a brief moment. The sound at 0:04 seconds was not audible in the car but came out in the recording (IMO this sounds worse than the rattle)

 

It'd "dieseling". overheating is usually the culprit with most cars. For whatever reason, the gas is igniting prematurely. That clacking sound is your valves. The clacking is not a big deal, but you need to get it serviced.

 

BTW- your video is set "private" so I'm just going by your text description.

 

Edited to public. Please let me know if you can see it now and thanks.

 

sounds like two whales having sex under a large pillow. sorry, except for the exhaust rumble, too muffled to make anything out.

 

pretty sure you need a service mechanic to handle this.

 

I don't hear anything unusual. Your description wouldn't indicate pre-ignition or detonation.

 

It is at the 10 seconds mark right as I hit the gas.

It is very hard to capture the audio. It sounds like a tambourine when I blip the throttle.

I took it to both Coventry Jaguar and The British Garage here in San Diego. Coventry said it might be bad gas so I filled it up with 6 gallons of 100 octane and ran that through but there is no change and the rattle/ping/I-dont-know is still there and seems to become more apparent the warmer the car gets.

The British Garage tech told me that all STRs ping and mine wasn't too bad. He said he owned a 2004 STR and his pinged as well. They said a piece of carbon might be igniting the gas prematurely. Do most STRs ping? Maybe I'm becoming hypersensitive to the engine? I have noticed more engine clatter after changing the oil (which was pretty dirty). I will post a vid up later today.

One final question, would it make sense to use a colder spark plug? I'm at 107,000 miles right now and I don't think this car has had it 100,000 service yet. I am thinking of the NGK (5344) IFR6D10 or NGK BKR6EIX-11 (3764).
Autozone/Amazon state these do not "fit" my car. Is that because they're not recommended or because they physically will not fit the well. I remember an older thread on this and somebody fit the colder plugs with no ill-effects, I would like to verify.

 

Why do you feel the need to change to a different heat range on the spark plugs? If you operate the vehicle in California, it must pass smog inspection.

The difference in the plugs may be the reach, or length of the threaded area. If the plugs have too long of a reach they can cause physical damage; too short of a reach and the fuel mixture does not ignite properly.

 

Could be cats breaking up.

Stick with OE plugs. They work really well.

 

False.

That would be 'pre-ignition', not 'detonation' or 'pinging', a completely different problem. If your mechanic doesn't know the difference, time to find a new one.

This will not affect a detonation problem one way or the other. If there is no evidence that the present plugs are too hot (the stocks plugs are know to be just right) then you're wasting your money and throwing another variable into the mix.

Then it is not detonation. I hope it was unleaded 100 octane?

 

Just a bit about pinging. Yes our cars can ping just like any car.


But the most efficient timing is right on the edge of pinging. So the control system is always trying to advance the timing only to be cut back by the Anti-knock sensors. Our cars have 2 to make sure any ping or knock is detected as soon as possible. This is VERY critical on a Super Charged engine like the STR. The factory runs SC cars very rich at full throttle to try and prevent any knocking/pinging.


You can get an idea of how this light pinging sounds by doing full throttle runs from a dead stop. That loads the entire car and drivetrain pretty heavy. Turn off the radio. (I add that from another thread where the guy could never hear anything and we finally found out he still had the radio on!).


You will hear small amounts of pinging and it's entirely normal as the car battle's to get the most power out of the fuel you are running. That's why running better fuel does not gain anything unless the engine can add more timing. Sometimes it can and sometimes it can't. Depends on conditions.
.
.
.

 

It was unleaded. I liked the tech but the part about all STRs pinging didnt sound right.

I just ran some redline si-1 in hopes that if it is a carbon piece that is embering it will be cleaned out.

The car is due for plugs. Based on the forum feedback here i am going to use ngk. There are two ngk iridium plugs that fit. I think the oem is $12 per plug but there are ones for $7 as well. These are the same part numbers as my post above but replace the 6 with a 5.

Are there any other maintenance tidbits i could do which may relieve this engine rattle?

 

Not the best recording I ever heard, can't really hear anything, but it doesn't sound like pinging to me, not that I can hear much over the exhaust...

How many miles on your car?

I went through a drama of detonation earlier this year, but my detonation was at the upper end of the rev range, not down low or at part throttle. Turned out it was choked cats...

 

The knock detectors are far more sensitive than human ears. Any detonation has been dealt with long before the driver could hear it in order to prevent engine damage.

Whatever noises are being heard, it's not detonation.

 

One more shot here -- You said it needs to warm up after 7-10 minutes... Makes me wonder if it's just a plug replacement will fix this problem as plugs deteriorate and perform poorly when not replaced on time.

Go with OE's. No need to complicate further.

 

OE are IFR5N10, which isn't just a 5 instead of a 6.

 

Right you are. My mistake.

Here is another video of the noise (can be heard @ 7 seconds and again at 9-10 seconds). It is easy to hear on my phone, a bit harder to catch on my laptop and almost impossible to hear with headphones (heavy rumble drowns it out). What might cause this noise? I am getting ready to change the plugs (see below). I am hoping that might help. If the knock sensor wasn't functioning would it throw a code?





Not to side track too much but I have noticed that the engine is noticeably louder after it has been run for a while. Is the following engine noise normal? Ignore the beginning when I say "Bank 1" I am actually holding the phone on the driver's side of the engine bay next to the oil cap. I then move to the passenger side near the firewall.





Finally, I am getting ready to change the spark plugs this coming weekend. I am undecided between the following:

NGK (7866) IFR5N10 @$12 each. Stock OEM replacement.
NGK (5464) BKR5EIX-11 @$6 each. Iridium IX and fit according to autozone.

NGK (5344) IFR6D10 @$11 each. similar to stock, one stage colder
NGK (6418) BKR6EIX @$6 each. One stage colder than the 5464.


I am leaning towards the 5464 or maybe the 6418 (in consideration of the noise being heard). Any thoughts?

 

Yes. I hear no detonation in the video.

Yes, normal


If you're convinced that that the engine has a detonation problem, why are you addressing it with different plugs/plug types/heat ranges?

 

Nothing makes me think there's a problem with plugs/coils let alone knock sensors.

You'd probably have codes.

If the fuel trims are OK I'd be happy.