5.7 hemi runs but no engine vacuum

[chris ok]

I'm working on a 04 5.7 hemi in a ram pick up. runs barely but has no engine vacuum
did a compression test. all cylinders ar 170-190psi.
has me puzzled.
cranks then revs to almost 3k then idles down to stall. on 3rd try will run 575 rpm area.
disconnect both vacuum lines and nothing changes
spray into throttle body, same.
runs on 4 cylinders barely, misfire, does not have the rms feature.
this was my afternoon friday.
any ideas?
engine load weas pretty high on scan tool. no engine codes.
had i think p0700 on transmission.

[Tom Meyer]

Sounds like the exhast is pluged

[chris ok]

thanks Tom.
First had 1,7,4,6 missing. was told it had the rms feauture but found that was wrong. tried compression test next. alls good. try to restart w factory plugs had bosch 4 electrode fully engulfed in soot. now different cylinder mis, lol.
will disconnect exhaust tomorrow a.m.
will let you know what I find tomorrow night.
thanks again, Chris

[Tom Goldman]

Like Tom said , sounds like a blocked cat.
P0700 is a generic transmission code that appears in the ECM when a code is present in the TCM.
Many scanners only read the PCM codes so the only one you see is P0700.
Any trans code will set a PCM code since transmission performance can effect engine load and emissions.

[ss3011]

Does this engine have an EGR valve?

[Ed Wright]

Originally Posted by ss3011

Does this engine have an EGR valve?

That's what I was wondering. Internally leaking EGR is a vacuum killer. If it has one see if it's hotter than the intake manifold.