Am I missing "Vacuum Control Valve"
 

Hi Guys,

I have a 2004 XG350 with about 60k miles on it. On the first startup of the day it stalls or idles rough, It clears soon if I rev the engine.

I started looking at the vacuum system and notice that I dont seem to have a "vacuum control valve". I have the solenoid and all vacuum lines are hooked up to the solenoid and EGR valve. The 2003 shop manual shows the part on the vacuum diagrams. Im not sure if they took it out of the 2004 engine design?

This is the part I seem to be missing:

https://cimg8.ibsrv.net/gimg/www.hyu...b79f0d8464.jpg


All help appreciated.

Bruce

Sorry don't know.
But, maybe you have a vacuum leak?
First start is usually rough
Then as the engine warms up the vacuum leaks gets sealed
Just a thought

There is a vacuum schematic/diagram on the inside of the hood. Looks like the EGR setup is connected correctly. They must have dropped this part from the design?

I am guessing that you are right.
Wish someone with more knowledge would help out

yes I think its not in this year.

Got it!
 

Ok so I think I have figured it out. The mystery of the vacuum control valve (not solenoid).

Background:
Shop manual printed in 2003. Car it is a 2004 production. Shop manual shows 'Vacuum Control Valve' in vacuum line from throttle body. My car does not have this physical piece (picture of piece earlier in this forum).

What Ive found:
So today after hours of trying to get my EGR system to work, Ive finally got it working and I was close to giving up. I had replaced the EGR valve, EGR solenoid and vacuum hoses(clue:this is the mistake).

So I connected it all up according to the vacuum diagram under the hood (which does not show a 'vacuum control valve'). The EGR valve turned on and stayed on and the engine was very rough and stalled sometimes. I was left scratching my head. The solenoid was off however.

Eventually I came to the conclusion in my head that the solenoid was not bleeding off vacuum sufficiently to turn off the EGR valve.

Almost giving up at this stage, I noticed a slight buldge/bead in one of the old vacuum hoses.

IN FACT THEY PUT A RESTRICTION IN THE HOSE (this must have replaced the 'vacuum control valve' in the design. THIS REDUCES VACUUM AND ALLOWS THE SOLENOID TO BLEED OFF SUFFICIENTLY. Put that section of hose back in and ....magic worked. manually turned on the EGR solenoid and the engine stalled. Yes, all working.