I have been chasing a rough idle problem . When I checked the vacuum at the nipple on the throttle body for the egr (yellow stripe hose ) there was no vacuum . Does this mean there is an issue in the throttle body or the EGR valve ?

Thanks in advance for any help you can give to help me figure this out .

 

how are you checking the vacuum?

I could be wrong but if you pulled the line off of the TB then I think there shouldn't be any. It should pull vacuum in by the intake mani.
check and make sure that the line didn't blow off from the egr side while under boost.

 

I am checking the vacuum at the nipple on the throttle body with the yellow stripe hose removed.

It reads 1-2 " HG. The manual says if this happens to clean the EGR , so does the egr provide vacuum to this point . I thought this would be a typical vacuum point with vacuum being produced by the intake .

The EGR is clean and functions. So why do I have no Vacuum ?

I also tested the EGR with a hand vacuum pump on the car. The manual says at idle, when warm, when 7.9"HG or more is applied the idle should go rough . My car started idle rough with less than 2" HG applied. Any thoughts what would cause this ?

I provided a couple of pics of the manual to show the test I was performing.

 

Opening the egr at idle any amount will start causing the engine to run rough. After all, egr stands for exhaust gas recirculation. When you start allowing already combusted gases back into the engine, it takes up space up space that other wise is used by combustible air.

Egr doesn't normally open unless your at cruise or decell.

I likely didn't answer your question with that.

If you've already cleaned the egr, and it has no vacuum at idle it's likely ok.

 

the nipple on the T.B. that goes to the EGR is supposed to have vacuum and it does not . Any thoughts on why ?

Why does the EGR have 2 vac lines going to it ?