5.7 hemi runs but no engine vacuum
 

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.

Re: 5.7 hemi runs but no engine vacuum
 

Sounds like the exhast is pluged

Re: 5.7 hemi runs but no engine vacuum
 

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

Re: 5.7 hemi runs but no engine vacuum
 

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.

Re: 5.7 hemi runs but no engine vacuum
 

Does this engine have an EGR valve?

Re: 5.7 hemi runs but no engine vacuum
 

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.

Re: 5.7 hemi runs but no engine vacuum
 

Monitor your IAT (intake air temp) on your scan tool data stream to see if the intake air temp is higher than your ambient air temp. Unless the exhaust is completely clogged, the engine vacumn should be near normal at idle. EGR stuck open will affect engine vacumn.

Re: 5.7 hemi runs but no engine vacuum
 

If the '04 RAM Hemi has the same EGR as the Jeep's , it's electric with a position transducer.....They nearly always set a fault for either EGR or air temp out of range with coolant.
Still something to look at. When the EGR'S were mechanical ,that was the first place we looked....Any more ,I see more and more wierd problems not setting codes.

Re: 5.7 hemi runs but no engine vacuum
 

Good evening guys.
Yes the hemi has the electric egr on the front right side head.
removed o2 B1 sensors fire it up
no change.
crank it and strarts revs to 3000 almost, stalls after short attempts to run.
egr is out of the manifold. no vacuum, booster out no vacuum. plug them in. crank it w hand over throttle body, same stuff, revs but lil less. somewhere a big ***** vacuum leak.
remove intake.
split open in back underneath bottom. must've had some back fire in its recent past w new coils and plugs and o2's, and new fuel tank and pump. they gave up trying parts and sent to us. I'm only a tech there a week. Got screwed over by Lexus big time.
Ram needs an intake to start. Customer says will pay 1000. we say no.
It did not even run till I played w it a few hours so far. not a fun truck to wrench as Tom Goldman would know, and many of you others.
can't hear the vacuum leak with the insulation on it and ratty exhaust manifolds.
what a mess. pushed it out, next bring on the patriot with falling out ball joints, lol.......

Re: 5.7 hemi runs but no engine vacuum
 

I had a customer last week with a 5.7 Ram with misfires all over the scale, if you go into Chryslers parts look up system and pull up the cam pn# a tech note will pop up advising you for multi-cylinder misfire to replace the cam and all 4 lifter banks.... Also they tell you if the Hemi every experiences "catastrophic" engine failure not to reuse the intake due to debris or cracking...