any body have any issues with the 5.0 litre supercharged engine detonating and holing a piston?
at a loss as to why , 2010 model , 22k miles fsh
only mod is upgraded pulley ! would that cause failure?

 

jagal, a motor letting loose like you are describing most likely is the result of either bad parts from the get go or the oil pump failed and that resulted in things going south. Unless you went wild with the pulley, odds are, that would not cause what you saw. Granted, be ready for Jaguar to say that the pulley is the cause of the problem. These days, most manufacturers will blame any fault on any aftermarket addition to a vehicle. I have heard of them trying to blame electrical faults on a muffler upgrade. Some people will buy it, but the wise people will not. But, they will try.

Wish you luck and sorry to hear that the kitty is not feeling well.

 

First I have heard of it.... Been on the forum for 2+ years....

 

Scotland eh!?

 

This must be the week for blown 5.0L engines. Have been around the forum for some time, but this weeks news from a few XKR 5.0L really sets the pace and record for reported problems with engines.

Let's hope no one else suffers these problems.

 

The most common issue with detonation and piston desctruction is fuel pressure sensor. If it goes bad a ECM may lean a mixture and destroy an engine.
Pulley can't be a reason of an engine damage. Also, in a most cases, the swappen pulley may remain unnoticed by a dealer, unless you tell them about it.

 

same here. again all engines from a basic 4.6 ford v8 block to a 351 chevy to a 5.0 engine in our jag there will be engine failure. no engine is bullet proof but it is not common for the 4.2 or 5.0 from what Ive read over the last 2-3 years.

 

jagal welcome to the forum.

I've merged your two threads into this one.

Please don't forget your intro in the new members section.

 

As a point of interest I saw a few 5.0L used engines for sale and they seem to range from $6-$8K. https://www.google.com/search?q=jagu...ngine&tbm=shop

 

Moscow eh?! A Jag is prolly most rare and I would think utterly expensive in those parts!!!

Loth

 

I suspect there is more to this story, so more info would be useful, including amount of boost increase. Increasing boost level with a pulley can increase the chance of detonation from too advanced timing or lean air fuel ratio. Pulleys should be installed with a tune to ensure safe operation. Was there a reason you skipped doing the tune?

Low or insufficient octane can also cause detonation. What were you using? Did the car go into "limp" mode, or experince any loss of power before this?

 

allways ran premium fuel. just started to pink then misfire ,causing excess crankcase pressure and oil got forced thro the filler cap,so def a piston melted. it still starts and drives but its down on one cylinder , parked it up at present awaiting stripdown.
with hindsight I wish Id had a remap but thought it would have been fine ,was certainly advertised as not requiring one
as I said , only upgrade was the top pulley , I bought the car used with 22k miles on and bought an upgraded pulley as you do.
, had them on all my previous xks and worked fine , im not saying this was the problem but may have contributed to it,
ill get the engine out and see exactly whats happened
im a bit disappointed to say the least. just wanted to know if this was an issue with these engines
cheers al

 

cheers and I will thanks

 

good guess ? or insider info? lol
yes Scottish born and bred

 

It seems from the engine failures reported for the past couple of weeks that our engine management systems are NOT as fail-proof as we would have believed. Ping should be detected and timing should be pulled automatically. Yet, Jagal had lost the engine following a ping and misfire. Sounds like too much boost for too few octanes in the gasoline...

Be careful with the mods....

 

If the mixture is too lean, the ignition retard can't help with pinging.
Failing fuel pumps or failing fuel pressure sensor will cause extreme lean failure, no matter of boost level or ignition retard. And that extreme detonation can destroy a piston within a few minutes.

 

Jagal,

Have you checked the service history on the car prior to you buying it in case there had been an existing problem or repair? A dealer could likely pull up history from day one with the VIN. It sounds like you bought it with 22k on it, put on a pulley, and had this problem right away as it's still at 22k?

Previous owner may also have improperly modified the car and removed them prior to sale and there won't be a record of that. Where you yourself skipped the tuning part of adding a pulley, some others here do both pulley and downloaded tune and never check air/fuel ratios afterwards, 'assuming' it's okay. Some tunes even require higher octane levels than premium and owners don't even know about that. Can you be sure yours didn't have a pulley before, and doesn't have a tune installed now or previously that the previous owner didn't want to tell you about?

Albert, until cause is known I don't think anyone should jump to any conclusions about the engine's safeguards being inadequate. The other engine failure with a bad water pump may have been preventable had it not been driven after the warning lights started flashing.

 

Bruce - my comments regarding the engine management not being as fail-proof as some of us would have considered, still stands. Yes, I would have expected a more urgent warning issued in the case of the failed water pump and subsequent overheating.

Moscow Leaper's comments about potential fuel pump failure, causing the latest engine failure, is also valid but, again, there are a number of fuel rail and pressure parameters logged by the engine management system that, I would expect, would pick up and alarm on weak fuel delivery that would cause a "lean" running condition.

These issues are very similar to ones I used to deal with in my Engineering profession as a Specialist Engineer. I dealt (still do) with computerized systems where the manufacturers swore to have full security and full notifications features for any failures, yet, those microprocessors were found failed many times without any alarm or notifications. Instead of scanning ALL parameters, they tended to scan only "selected" parameters for alarm purposes.

 

ML - Yes, I know all about that. I blew an engine in my RX-7 on the very first day of my ownership when I accelerated to the redline. It was a weak fuel pump that worked fine under normal driving conditions but, was unable to provide enough fuel under full, high RPM acceleration! But, that car is a '93 model and it lacks all the sophisticated electronics that today's cars have. I would expect modern cars to immediately recognize inadequate fuel pressures/delivery and cut power to the engine.

 

Some fuel pump's flow decreases below rated capacity as boost and fuel regulator pressure increases. Not sure if Jaguar's are like that.