Well the hypochondriac ECM has given me a new code . P0171. Lean condition. My MAF is within scale so I decided to put the smoke machine on her. I have found the tiniest bit of smoke coming from around the bottom area of the throttle body. I can find no vacuum line diagrams online anywhere so I’m coming here to see if anyone can clue me in what would be a common leak from that area so I can not waste too much work chasing this down.
I mean , it’s a small leak, but apparently enough to cause the amber pill to light up and the restricted performance to display. It comes and goes too.
Anyone?

 

put your car in the description next time

you’re probably looking at the brake booster vacuum fitting o-ring and push connect insert. most common vac leak by far

 

2004 XJR

 

I concur with xalty, the connection to the brake booster was the first thing that came to my mind when reeading your post.

Best regards,

Thomas

 

Much appreciated, I will investigate.

thanks

 

If our suspicion is correct, you will need this spare:

Don't ask why Jaguar also includes the brass fitting, because most probably you will not need it.

You will only need the o-ring that is in the brass fitting and the plastic part for reattaching the vacuum tube,

Best regards,

Thomas

 

Great, thank you.

is this a bugger to get at ? Looks like it’s under throttle body ? Correct?

looks to be on the lower plenum, is it serviceable on the car ?

thanks

 

I would say that it's "YES" to all your questions.

If you search the forum for threads regarding the replacement of the valley hose, you basically have a good description of the work to be done. I don't know if you can access the part without the removal of the supercharger, as I have accessed it when I did the valley hose.

If yo can access it only by removing the supercharger, I would recommend to do the valley hose, as well.

Good luck.

Best regards,

Thomas

 

Much appreciated, I will do my due diligence and start gathering up parts.

Thanks

 

set the throttle body aside and use a pick. getting the o-ring installed is the only tricky part. if you still have issues or the pipe is scratched up just use a ton of right stuff rtv it will never leak again

 

That area is minimal usually leaking through the tb shaft. Shouldn't be enough for that code but could be I guess. I have same leak and no codes.

 

Oh i read it now its the brake booster line. I JB welded mine back in and all good, I also got rid of the coolant in the TB so I had room.