Re: Vac/Emissions gurus
Great drawings LEVE! Good explanations too.
Essentially however it's set up initially - you don't want EGR till it's fully warmed up, and then only at higher speeds under load.
Cannister purge - most systems are the same way, only when warm, only at higher speeds (purging the cannister causes a slightly rivher condition till it's empty.) But then there's always the exception - some systems use the cannister purge to enrichen the system during warm-up - as a form of artificial enrichment - like a choke does.
Sometimes there are more than one ported vacuum - which to use for what?
As a general rule - of course with exceptions - put a vacuum gauge on the ported vacuum - rev it up:
- distributor vacuum will come on slowly the faster you go. - EGR vacuum will not be there until you reach a higher speed - but there needs to be something that keeps the EGR from working untill it's warmed up.
For purge you can use either one.
Many Jeeps use 1 or 2 control solenoids stock. They are operated by the computer - the computer determines if the temp and speeds are right. Then the solenoid(s) opens up, letting manifold vacuum through to the distributor, EGR, and purge. Everything happens at one - sometimes when driving it you can "feel" it all kick in. It hurts mileage but gets them past the smog laws.
When this type of system is removed, I've found folks really get things screwed up!
Back to basics - remember why, how, when each system should operate.