mgmuscari

Saw the last post on this thread was you and actually said "yessss" out loud before opening it... all of what you said makes perfect sense and corresponds perfectly with everything i'm planning to check. I wasn't aware that there were oil passages in the intake though... i guess they just join the heads?

edit: also, instead of red rtv this time i'm planning to use permatex 3h aviation grade sealant which is fuel resistant. sound reasonable?

mjr46

I just use permatex's "the right stuff" but only a little around the coolant ports and I throw away the cork ends seals and use the sealer in place of the end gaskets, you can lay the intake on the heads/block first and use a feeler gauge around it to make sure that the intake is seating properly, if not, may need a milling, but this is just a guess. There are no oil pasages in the intake but it does seal the valley off from the intake ports on the heads as long as gasket is seated properly when you pull it off , inspect head ports to see if you can determine which particular runner may have been pulling oil in, via a possible mis-seated gasket....

mgmuscari

Thanks for the info... those cork gaskets are a real pain, would be nice to ditch them.

There is now a big puddle of oil under the car in the garage, i'm not sure where it's coming from yet but will take a look next week, i'm busy for the next few days.

Determining whether the intake runners are sucking oil from the valley will be difficult because the PCV already sucked up an extreme amount of oil into the upper intake. It flooded my vacuum hoses, which I had to drain of oil...

We'll see what's going on with this thing next week, i've put together a pretty detailed plan to diagnose it at this point.

TrimDrip

I had a buddy that had a nitrous explosion resulted in being similar to your problem. It blew the gasket and was sucking air out the back of the intake where the corked gaskets would have been.

Did you put the screen under pcv valve?

mgmuscari

yep, screen's under there as well as the baffle.

TrimDrip

When you redo it, put you a stud at every corner of the intake. It makes it a whole lot easier to set it.

Old Mustanger

It sounds like you have done proper research and you have your act together.

I would definitely plug the PVC valve hose for now. A new engine will have crankcase pressure, this will cause excessive flow through the PVC valve. A high performance can build significant vacuum and crankcase pressure.
If the PVC valve is sucking too much air it will really cause problems with your engine running and debugging.
Also, the oil being sucked through the intake will cause a lot of running issues. Aerated oil will cause pre-detonation.
After you get everything running good, you will need an oil catch can to catch engine oil after the PVC valve.

TrimDrip

That is a pretty good idea. Only problem with the idea is the tuning part would maybe be a little more headache since the engine won't be pulling vacuum. Then again it may not affect it all. I have never tuned a car so, I really don't know.

mgmuscari

So, it's been a busy month and I haven't had a lot of time to work on the Stang until this week. I have ended up relocating my PCV valve to the driver side valve cover, with the breather hose in the same location as stock (between filler tube and intake elbow).

Today I finally got around to starting it again, after relocating the PCV, carefully checking the adjustment of the rockers, cleaning out the intake thoroughly, draining the oil out of the vacuum system (yikes), cleaning the intake, purging the oil from the cylinders, and replacing all the plugs which had fouled up.

Lo and behold, today it started up pretty well, albeit with a couple of hiccups.

- I have a vacuum leak that I'm going to fix tomorrow (which explains the idle surging and high idle speed)
- The MegaSquirt had overrun fuel cut turned on (which I didn't know about until viewing datalogs later), which was causing the computer to intermittently command zero pulsewidth to the injectors, causing a lean/misfire condition (this explains most of my problems including why it's running a bit rough, not to mention that I haven't dialed in the VE tables yet).
- The timing table was set way too low at the higher load levels near the lower RPM region, because I pulled a few degrees here and there before I started the car to make sure it wouldn't knock. I forgot to bump all the cells up to at least 10 degrees before starting it.
- I went with the recommendation that came along with my cam and set the lifter preload to 1/8 turn past zero lash. Comp Cams seems to recommend 0-1/8 turn of preload in general, but I think the valvetrain is a bit noisy, so I think I may tighten them down to 1/3-1/2 turn instead.

Tomorrow I'll be working on getting it to idle OK without IAC, and then I'll be working on getting the IAC valve to keep it rock steady.

Here's a video of it while I was trying to diagnose the roughness and the surging in realtime, and a bit of revving the engine to see if it breaks up at higher RPM toward the end. My camera has a really crappy microphone, and the recording has a lot of tinny distortion in it. Sorry about that.


EDIT: Oh, and notice - NO SMOKE

EDIT 2: Datalog showing the the accel enrichment / overrun fuel cut is indeed what's causing my erratic fueling. It correlates perfectly.