Thinking I have an internal vacuum leak from the intake manifold and I could measure the volts on the idle air control valve to help diagnose. Any one have the specs at idle rpm? I looked in RAVE and it says seeing testing section which I do not have.

 

Thinking IACV is leaking internally? A small hand vacuum pump would likely be a better way to verify leaks in valve or other lines.

Not sure how elect specs would be more helpful and none available I've seen. Didn't see in Manual to see testing? It may be referring to idle RPM specs for testing? Possibly you could find your desired specs somewhere (?) with a deep web search using mfg. and other key search words.
......

 

I'd check the 6 bolts that hold the intake manifold on (4 long ones & 2 short ones) Make sure they're tight (I've seen plenty that are just finger tight...), then I'd check the red clip for the brake booster vacuum line (I've seen plenty broken from people removing them wrong), and also make sure the nipple on the air intake that goes to the IAC isn't ripped/torn from the air intake tube. Also if you vehicle is SAI equipped check the connection at the intake for leaks (if it doesn't have SAI it will have a cover over the vacuum nipple located just behind and down from the red clip for the brake booster line off of the intake). If all of that checks out you "could" have a bad upper intake gasket.

IAC wise remove it, and rotate it. The internal part should rotate freely. If it doesn't clean it out with some brake cleaner.

 

Long story short, I’ve been fighting a heavy oil consumption issue since I bought the truck in July. Have since rebuilt a fully rebuilt engine and the problem seems worse. I have ruled out blow by (bypassed pcv), rings new (compression ok) and so the only thing left for oil to enter the combustion chamber is the intake manifold. Was thinking the IACV reading being high would confirm an intake leak. Tried a vacuum test on the crankcase but the couple lbs of pressure is greater than the vacuum leak.

Was wanting another test confirming that is likely the problem but will tear down to the valley pan and inspect how it sealed and if oil is getting sucked into the intake runners. Beyond frustrated with this engine but I will find the problem. Intake was milled flat on rebuild and no, I don’t think they screwed it up. Engine runs great and idle is perfect.

 

Got the intake off. Definatelty the problem. Oil in runners and pooled in the heads by the valve. Can see oily pathway on each intake port on the valley pan gasket. Will take the manifold and gasket to the engine machine shop on Monday for suggestions on correcting. Maybe installation error by me.

 

Did you use any type of sealant on the gasket, especially along intake to heads?

Personally, while doing gasket refresh on 04 engine before dropping it my 03, I thought the valley pan gasket was a poor fit, garbage. Actually reminded me of crap l use to see when l started in this profession forty years ago. Anyhow. So I put ultra gray prematex on each side (lightly) and have had no issues (but, the day ain't over yet...and probably just jinxed myself terribly...lol).

Brian.

 

No sealant but thinking to use on reassembly. Never have on an intake on any car before though