i have a 2000 jaguar s type with the 4.0 engine i just replaced the broken tensioner and now the engine has entered failsafe mode how do i get out of failsafe mode i dont have any codes so i dont what could be wrong i'm not getting anywhere fast with this

 

Did you start the car without primiing the new tensioners (cranking with the fuel injection relay removed)? Is it running rough now?

If yes to both these questions, your chain may have skipped a tooth. Remove the valve covers and check that the camshaft flats are aligned.

 

before the tensioer was replaced the engine had already skipped a tooth, maybe 2. fixed that, engine stopped on the road, acted the same way when it happened. That's why I am thinking it is a protective issue. The misfireing that existed befor it broke down appears to be gone.

 

If you skipped more than one tooth, you may have valve damage.

You could also have non-generic codes that your reader is missing.

Does your reader allow real time monitoring of engine parameters? That may provide some clues, as might a compression test. Also with some driving it may eventually set a code.

 

unlikely, skipping a tooth or 2 will not cause valve damage it just will not be timed correctly i have no codes if you read above, it said "failsafe engine mode" on the LED screen and how can i drive it if it wont stay running???

 

It was not clear to me that you were not running. You had said the misfiring was gone, so I assumed it was running.

In any event, whether you have valve damage or not depends on engine design and some element of luck. It is well known on the Jag 4.0 that one tooth skipped will cause rough idle, two or more teeth skipped may cause valve damage.

 

If it is a non-supercharged model, consider whether the VVT is out of position.

 

False. It's an interference engine so skipping can be expected to cause serious damage. Other people have reported damage has occurred. Hopefully yours hasn't skipped.