Forgot to mention if you unplug the fuel rail sensor. The car still feels rough and doent have much power but throws no misfire codes. Installed a genuine jag fuel rail sensor.

 

try watching the sensors via obd2 , for fuel pressure and MAF sensor gallons per second . should idle around 5gps on the MAF , and have 55psi fuel pressure .

and check the fuel trims also .

 

 

 

Fuel pressure of 3.8 bar is correct.

 

Check for vacuum leaks at the inlet manifold and the wiring to the injectors.

 

 

 

did you happen to replace an o2 sensor recently

 

It could well be a cat issue ,
But you still need to check the MAF sensor readings .

 

 

 

 

 

i cant imagine a cat being so blocked it would affect idle .and if so you could visually see the damage when they are off. normally when the cats fail it affects higher RPM's first .

9.91 g/s is too high. it needs to be 4-5g/s at idle.
try cleaning the sensor with MAF cleaner
and try again
just make sure the car is running in closed loop when you check .

 

 

Not to be a #%@©, but what method(s) did you use to confirm this? Not all methods find all leaks, so sometimes you have to mix it up.

I've been very reluctant to jump into this thread because I've seen a LOT of squirrel chasing in lieu of methodical troubleshooting. Don't mean to be harsh, but I'm about ready to break out the tranquilizer dart gun.

When you had the O2 sensor removed, was it still connected electrically? That isn't going to tell you much. With the sensor out of the exhaust stream, the poor computer is going to trim its brains out trying to compensate. Such results aren't going to help much, if at all. You might get some helpful info by electrically disconnecting the sensor instead. You'll get a fault code set, obviously, but the computer will then substitute preprogrammed values for a dead (disconnected) sensor.

 

I’m squirrel chasing because I’m running out of options. Plugs were changed and coils. Checked to make sure each was getting spark with a tester. Checked fuel. Checked each pigtail going to each injector. While the intercoolers were off I checked for any cracked hoses for leaks and then after I was done I did a smoke test. No leaks. Then I did a leak down and compression test in each cylinder. Good there. Check for bad grounds looks good there. Last time I had an issue the car shifted funny and couldn’t figure it out and turned out to be a mass air sensor and the dealer figured that out as the car set no codes or faults. Pretty lost and a clogged cat or O2 is the last I can put my thumb on this list possibilities.

 

Maybe a vacuum leak?
Codes don't point to it but?

Try this thread for some more idea's. I had a few problems!

https://www.jaguarforums.com/forum/s...-p0174-149418/
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