Hi everyone, I hope you all have wonderful time with your Jag today.

I would like to know if a Jaguar should rattle when the “engine fail safe mode” is on, or not.

Here’s a detailed description of what happened today:


I bought a Jaguar XJ 3.2L v8 Executive(1999) automatic, whose mileage was around 120000km, and it drove fine until recently.

One month ago, I noticed a flash of the “red ABS mark” and “stability control failure” with a yellow warning light shown on the display. However, because it only appeared for 1 second when I started the engine, and they would go off right away, I ignored them thinking the car sensor was sensing false information.

Then, this morning, for the first time in a long time, they didn’t appear when I started the engine, and I thought the error was gone!
However, when I was on my way home, the “stability control failure” with RED light and “engine fail safe mode”appeared on the display, and they wouldn’t go off…
My Jag slowed down and rattled as if I had been driving on a bumpy road.
When I changed the gear from D to R to park, there was a big shock and the car reversed much faster than it would normally do without acceleration.

After that happened, I read many threads possibly related to my situation, but I’m not sure why the car rattled violently.

Is it because:
a) the car rattled because it thought something was wrong, and was forced to switch to “engine fail safe mode”?

or

b) there actually was a problem that caused it to rattle?

or

c) something else?


Thank you for reading from Japan!

 

It should not rattle or shake. I’m assuming this rattle sound is coming from the engine? If so, *do not* try to start it again. You need to remove both cam covers and check to see if the plastic secondary timing chain tensioners have been replaced with aluminum ones.

 

[QUOTE=Huritchel;2731653]Hi everyone, I hope you all have wonderful time with your Jag today.

I would like to know if a Jaguar should rattle when the “engine fail safe mode” is on, or not.

Here’s a detailed description of what happened today:


I bought a Jaguar XJ 3.2L v8 Executive(1999) automatic, whose mileage was around 120000km, and it drove fine until recently.

One month ago, I noticed a flash of the “red ABS mark” and “stability control failure” with a yellow warning light shown on the display. However, because it only appeared for 1 second when I started the engine, and they would go off right away, I ignored them thinking the car sensor was sensing false information.

Then, this morning, for the first time in a long time, they didn’t appear when I started the engine, and I thought the error was gone!
However, when I was on my way home, the “stability control failure” with RED light and “engine fail safe mode”appeared on the display, and they wouldn’t go off…
My Jag slowed down and rattled as if I had been driving on a bumpy road.
When I changed the gear from D to R to park, there was a big shock and the car reversed much faster than it would normally do without acceleration.

After that happened, I read many threads possibly related to my situation, but I’m not sure why the car rattled violently.

Is it because:
a) the car rattled because it thought something was wrong, and was forced to switch to “engine fail safe mode”?

or

b) there actually was a problem that caused it to rattle?

or

c) something else?


I'd expect you are in FAIL SAFE mode with no ability to accelerate...the car just runs at about 1500 RPM. You can check the codes without the engine running and at least get some idea of the problem. In my experience, if even one spark plug coil fails, the car runs very bad and shakes and will enter Fail Safe.
If the cam chain tensioners have not been replaced you may have jumped a tooth on the sprocket which may also be the trouble but at this point, I would get a reading on the codes before I did anything. Whether it's a faulty coil or something else wrong, replacing the tensioners is important to the life of the engine.
Please post you findings to the group. Always glad to help a brother.....

 

Without reading the codes being given by your car's computer, everything thrown out here is 100% guesswork. You could have a timing chain problem, bad pedal position sensor on your throttle body (I recently experienced this), bad spark plug or coil or any of a hundred other issues. Plug in a code reader and get those codes, do not drive it or even start it until there is more information as you could potentially ruin your engine if your timing chain has skipped.

 

Tensioners! Its timing is off!

 

Do not attempt to start it again until you remove the cam covers and inspect the secondary tensioners.

 

Did you get it towed to a Jaguar mechanic to look at it. Like others said, don’t drive it until the secondary chain tensioners are checked.

 

Thank you very much everyone for your informative comments!
I had the issue 50m away from my house and I drove back on that day.(Hopefully, it didn’t do much harm on the engine)
I called a car mechanic nearby, and he said he had a tester. However, I’m not sure what machine he has.
Tomorrow is a national holiday in Japan, and he won’t be working. I’ll call him on Thursday, and I’ll ask if his tester can check:
a) spark plugs
b) timing chain
c) throttle
d) pedal position sensor

Maybe I can check on the cam cover tomorrow (if I can)
I’ll keep you updated, thank you very much!

 

If you have a failed tensioner and the chain has skipped a tooth, there may not be any engine damage. However, if you attempt to start the car and the chain skips another tooth, you will likely have bent valves. So do not attempt starting until you have checked the tensioners.

 

+1

swap your a & b. Do NOT start the engine!

 

The car mechanic I’m going to visit said it’ll costs 25GBP or 33USD to run a tester as they need to pay subscription fee to a company.
Now I’m thinking to get one for myself if it’s not too pricey, so I can check my Jag even after this fix for maintenance.

Does anybody have any recommendations for a tester for x308 that covers for the spark plug, throttle, and pedal position sensor?

 

also check the throttle body,, it is a common issue also with this symptom

 

I have a Foxwell 630 that I bought in 2020 that does everything needed on my XJR and has worked well on every other car I've used it on. Its an older model and I'm sure there are other options, but this is an example of the type of reader I would look at.

 

Happy with my Foxwell NT530. Does everything I need including isolating airbag faults.