Efi pcv

[blainebrazil]

I am converting to efi. There is a nipple on the throttle body that is supposed to be connected to the nipple on the passenger side valve cover. I dont have efi valve covers. I was running a pcv breather that was connected to the bottom of edelbrock carb. can this pcv breather be connected to the throttle body nipple or do i have to get the efi valve covers?

 

[ransil]

The EFI valve covers are sealed. the PCV system works by drawing air into the nipple on the throttle body which gets its air from the air filter via the MAF which meters the air. then air is then drawn in to the crank case removing what ever it removes and the motor using vacuum evacuates the crank case via the PCV valve via its filter ( metal mesh thingy in the hole) change the PCV filter when installing a used motor as they tend to coke up and clog.

this is MAF EFI only as the MAF meters the air. but the sealed valve covers are also used on speed density systems and they don't hurt.

 

[blainebrazil]

so, i should get a set of efi valve covers to make everything work correctly

 

[ransil]

Yes if you want it to work correctly.. ;D

 

[HoosierDaddy]

From my understanding , you will never get it to idle worth a damn until you get it sealed up properly.

 

[Steve83]

There is a nipple on the throttle body that is supposed to be connected to the nipple on the passenger side valve cover.

No, that goes to the CANP valve, which goes to the charcoal canister.

. .

The EFI valve covers are sealed.

No...



%) Read that caption for a description of the PCV system.

 

[ransil]

I stand by my post in #2

 

[Steve83]

Here's another pic of the '88 F150 5.0L as it was going into Frank's '75.



The PCV in the valve cover is easy to see, just like that last diagram above. So if "sealed" means no PCV ports, then they're not sealed. If "sealed" means they're not vented directly to the atmosphere, then they're sealed.

 

[DirtDonk]

No, that goes to the CANP valve, which goes to the charcoal canister.

It might on some, but not on all. In some applications, that nipple (most are 90° that I've seen) is absolutely for the PCV air return. And even if not used that way originally, for a particular application, if you're not keeping the canister-purge function, that TB nipple can be utilized as a convenient hookup for the valve-cover fitting.
Some apps have a nipple molded into the plastic intake tube between the TB and the MAF, a lot don't. Still others (Mustang V6 for example) use the nipple in the air tube, but simply plumb the CAN-P into the PCV valve's vacuum line with a "T" fitting.

Paul

 

[DirtDonk]

Here's another pic of the '88 F150 5.0L as it was going into Frank's '75.

Where did the fresh-air return (or whatever it's proper name is) hook up on that engine?

Paul

 

[Nightstick]

<--------- confused!!!

 

[Steve83]

In some applications, that nipple (most are 90° that I've seen) is absolutely for the PCV air return.

Yes, it's a manifold vacuum port (downstream of the throttle plate), so it could be used for PCV return (vacuum). But it can't be used for PCV fresh air (intake) since that would produce NO flow (manifold vacuum on both ends of the system).That was the impression I got from the OP.

However... Using it for PCV vacuum means all the sludge that makes its way thru the valve gets dumped right behind the throttle plate, and coats the entire plenum & intake, and some of it runs back into the EGR valve (when it's closed), and might find its way into any OTHER manifold vacuum port. It's much better to route it further down in the plenum where it can stay hotter, keeping all the volatiles from condensing in the line, or ever being liquid/gel in the intake. That's why some later PCV systems are heated between the valve cover & the intake.

For the PCV system, hotter is better, and that location is the coldest on the engine.

Where did the fresh-air return (or whatever it's proper name is) hook up on that engine?

Side of the filler neck (as the diagram in post #6 shows), which is why that tube runs straight up a few inches before going across to the filter box, and why Ford published a TSB about jamming a shop oil nozzle into it sideways & pumping 6qt into the filter box.

 

[DirtDonk]

<--------- confused!!!

Don't get confused just because there are multiple answers for one question. After all, this is a Bronco thing, added to a potentially hybrid mix of parts off of other (and often multiple) applications.

It's what we get ourselves into sometimes.

Paul

 

[DirtDonk]

Yes, it's a manifold vacuum port (downstream of the throttle plate), so it could be used for PCV return (vacuum). But it can't be used for PCV fresh air (intake) since that would produce NO flow (manifold vacuum on both ends of the system).That was the impression I got from the OP.

We're talking about different fittings then. The ones I'm talking about are all upstream of the throttle blade. Between the TB and MAF then, not between the TB and plenum.
Therefore not full manifold vacuum, and theoretically at least, appropriate for use as the fresh-air part of the PCV.
I didn't look at your pics that hard I guess, but couldn't see where the fitting was you were referring to originally. I'll go back and look again.

Paul

 

[DirtDonk]

Where did the fresh-air return (or whatever it's proper name is) hook up on that engine?

...which is why that tube runs straight up a few inches before going across to the filter box...

That last is what I was wanting to know. Does that mean this is a Speed Density system then? I thought the air needed to be fully metered, and therefore had to come in after the MAF? Anything that's in the air box itself, would be before a MAF sensor. As far as I know anyway.

So that F150 app had the clean air coming into the valve cover from the filter housing then. Some have it in the tube (MAF), some in the housing (SD?), but if you're running a factory tube that doesn't include the nipple, and a cone style filter right ahead of the MAF, there is no convenient fitting to hook the valve cover to.
You could add a fitting to the tube of course, but there is that nice little 90 degree 3/8" barbed fitting just ahead of the TB that's soooooo convenient.

Being that the one I'm using, and maybe the one that blainebrazil is using too (we'll have to verify that) is in the TB casting, but in front of the blades, do you still feel that there's anything in your info that's pointing to that not being a good location?
It seems to work on the ones I've worked on, but I'm open to change if it's not the optimal location.

Paul

 

[av bronco]

I gotta cure for the pcv question, Im not running any stinkin pcv valve, just the header evac system, pulls vacuum like a mutha, had to baffle it to slow it down a little.

 

[DirtDonk]

Hah! Well, I can't argue with your results (though I may try later), but why would you want to limit the pulling power of your system? I would think more is better
Unless you're actually sucking oil out of the sump that is!

Paul

 

[av bronco]

Thats exactly what happend, had to baffle it or total smokescreen. still pulls twice as much vacuum as my old pcv.

 

[Nightstick]

I don't wanna hijack this thread, so I'll just ask the OP if he's running a MAF or speed density system?

I'm putting the pieces together to run a MAF system and went with a TFS TB which is identical to the explorer TB with the exception that it's 75mm instead of 65mm. Maybe I'm just confused on people's terminology on what a nipple is. That and I bought the parts from another person instead of taking them off myself, so I never saw them hooked up. NIPPLE to me means a rubber one way valve. A metal elbow that a hose would be attached to isn't a NIPPLE in my language. Here's a pic of my TB, is the nipple y'all are referring to the same item as the elbow at the bottom?

 

[ransil]

I don't wanna hijack this thread, so I'll just ask the OP if he's running a MAF or speed density system?

I'm putting the pieces together to run a MAF system and went with a TFS TB which is identical to the explorer TB with the exception that it's 75mm instead of 65mm. Maybe I'm just confused on people's terminology on what a nipple is. That and I bought the parts from another person instead of taking them off myself, so I never saw them hooked up. NIPPLE to me means a rubber one way valve. A metal elbow that a hose would be attached to isn't a NIPPLE in my language. Here's a pic of my TB, is the nipple y'all are referring to the same item as the elbow at the bottom?

My reply is based on that metal elbow being called a nipple.