I have a 1998 XJR I’ve been having problems with the car, not starting it will continue to crank but wont run I have a fresh battery charged up it has plenty of juice. I’ve been tried to depressed the gas pedal all the way and hold it. I think that cuts off the fuel injectors momentarily, and it started up, but it ran rough and a lot of smoke from the exhaust. I let it run for a few minutes shut it off and still won’t crank over again unless gas pedal is fully depressed. And now I’m getting knock sensor codes I don’t know what should I do?

 

Try looking up "bore wash" and give this a look as well...

...I clipped off the wiper detail since that isn't the issue here.

 

Thank you so much for the video. I’m gonna try that this evening.

 

The X - 308 has a specific fuel injector relay that can be intermitent , it will crank all day otherwise with no fuel

You should have relay swapping options

Fuel pump underperforming ? ( 43 PSI ) , you can jumper the fuel pump relay socket 3 to 5 and inspect the on the fuel pump connector for burnt sockets ( fuel pump itself failing will damage these 2 )

Bore wash is a condition that you can " walk " into but a lacking relay is an opposite of too much unburnt fuel to cause a bore wash

You're doing the correct response to correct a bore wash assumption by hold the gas pedal down , but...........................

Knock sensor codes in this instance should be disregarded in my opinion until you get past starting sequence and the engine " settles down "

 

How is your fuel pressure while cranking and after shut down?
Does fuel pressure regulator vacuum hose smell petrol?
Try to isolate faulty cylinder by disconnecting injectors one by one