Hey guys, I have a 2002 4.6L that has been transplanted into a Factory Five MKIV. Computer was programmed to remove Pats/EGR/Secondary O2.

It starts, but does not hold idle well. First things first, there is a red vacuum line that I suspect may be part of the problem. Where should this line go? A picture or diagram would be helpful. Thanks again.

 

That vacuum line looks caped anyway. Poor idling is usually a vacuum leak. You'd hear air
going into that "Y" vacuum connector if it was not sealed. IT looks sealed. The intakes I see,
the TB is facing the left, not forward, and the line that comes out of that "Y" goes towards the
passenger side more, but can't see where. You would need to get someone else who has a 4.6,
same year, and follow the line. Someone here will probably know where it's supposed to go...
Or, that was changed to the Q45 intake, and they didn't route the RED line properly, or did not need
that piece.

Here you can follow it some more:

You can see it goes down, to the passenger side, and back, then connects where that middle red line goes
through...

 

It is connected properly on the other side of the engine that is out of the picture, I was just wondering if the side you see being snipped off and sealed would adversely effect performance, or if I should try to recreate the section that has been removed.

 

If it's not sucking in air, then it won't effect idle. Something else is... A partially stuck open
EGR would also cause bad idle, that's still a vacuum leak.

 

IAC Valve.....very problematic on most 4.6 motors I've had!!

 

Its not the EGR, the EGR was programmed out, and blocked off.

Replaced the IAC, same idle condition.

Any other ideas, or suggestions to troubleshoot?