Vaccum lines from valve cover, affect on emissions?

[oldmann]

Where should the hose from the front of the valve cover hook up to?

Same question for the hose off the ICV, back of valve cover.

On my 91 m42, the front hose goes to the AFM boot. The hose from the ICV runs to the bottom of the TB. Is this reversed?
Or does it make any difference?

If this is reversed would it have any affect on emission numbers?

Just failed an E-Test here in Colo., Just as strict as Calif., High CO #s.

[Vivek]

http://www.r3vlimited.com/board/showthread.php?t=253698

In the diagram the red is what you're looking for. But the stock routing sucks and it's not all that hard to clean it up properly.

[oldmann]

http://www.r3vlimited.com/board/showthread.php?t=253698

In the diagram the red is what you're looking for. But the stock routing sucks and it's not all that hard to clean it up properly.

Thanks, I've seen this diagram before, and your pics show the same, thats why I was questioning the way mine is plumbed.

I'll be changing my hoses around.

Still wondering if there would be any difference, vacuum from behind the throttle plates or in front.

[Dj Buttchug]

you can also run that VC hose to atmosphere. its just oil vapors and moisture puffing out.

[gt88]

Thanks, I've seen this diagram before, and your pics show the same, thats why I was questioning the way mine is plumbed.

I'll be changing my hoses around.

Still wondering if there would be any difference, vacuum from behind the throttle plates or in front.

Difference before and after the throttle plate:

Before, or between the throttle plate and afm, is "venturi" or venting vacuum, and tends to draw depending on the amount of air flowing past the orifice.

After the throttle plate is manifold vacuum, I.E. vacuum at idle, drops off when throttle is opened.

So, my concern would be sucking ambient oil into the intake at idle, and causing random mixture issues. Route this hose to the correct port, cuz several hundred german engineers arent wrong more than 50% of the time.

[bmwman91]

you can also run that VC hose to atmosphere. its just oil vapors and moisture puffing out.

I did that for a while. Whenever I was stopped at a light, I could smell hot oil / blow-by vapors lol. Mmmmmmmm.

[oldmann]

Difference before and after the throttle plate:

Before, or between the throttle plate and afm, is "venturi" or venting vacuum, and tends to draw depending on the amount of air flowing past the orifice.

After the throttle plate is manifold vacuum, I.E. vacuum at idle, drops off when throttle is opened.

So, my concern would be sucking ambient oil into the intake at idle, and causing random mixture issues. Route this hose to the correct port, cuz several hundred german engineers arent wrong more than 50% of the time.

This is what I was thinking, mixture issues.

Was barely failing emissions on CO only, IAC was maybe trying to do its job, but couldn't because of incorrect hose location.

Changed the hoses around, Idle is steady as a rock now.

Need to ck FPR operation, change if needed and try again.

[oldmann]

OK, ckd fuel pressure, 32psi, pinch the return line and no increase in pressure.

I pulled and plugged the vac line to FPR, no increase in pressure, engine stayed at same idle speed. Hooked up vac pump to FPR, ran vac up to 20 and dropped it to 0, nothin, no change in pump pressure or engine speed.

Vac reads 15 and steady at the hose from the TB.

The FPR is dead, Right? And what else? Am I missing something?

This car pulls hard to red line in all gears when pushed, I dont think the fuel pump is an issue.

Thanks in advance for any help.

[oldmann]

ANYONE?

Smartass remarks? NO?

PICS of your women? U wanna buy some?

[AndrewBird]

Seems that way. Fuel pressure should be much higher then 32 psi.

[oldmann]

Thanks, New FPR picked up today.