High idle, and BOV open at idle?

[Jaguar_5]

Hey guys I have a strange problem, I've done some searching here and on google and found no solutions or anything

My BOV is staying open at idle, as soon as I give it a bit of throttle it snaps shut - pinching the vac hose does nothing.

I also have a very high idle, about 1500, i don't have a code 51, there's only about 30 miles on the engine. I have a tial knockoff bov with a light spring, and I'm running Maft-Pro speed density

I'm not sure if this is causing my 1500 rpm idle, or is because of it! Maybe it's because of my timing? I 'sort of' set it at 10* but it was at 1500 rpm...

I'm pretty stumped by this one!

For more details on my car here's my build thread:
http://www.supramania.com/forums/showthread.php?t=20406

 

[jetjock]

BOV normally doesn't provide an idle air path around the throttle plate. Pinch off the idle hose and the PCV line going into the TB. Engine should die. If not there's either a pirate air leak somewhere or the throttle plate is cracked open. If the engine dies check the ISCV and reset timing with the diag block jumpered.

 

[Jaguar_5]

It still concerns me that it's open at idle :aigo:

I will try and pinch off the ISC valve, funny I had that idea but forgot about it when I actually had time to work on the car :biglaugh: Didn't think to pinch off the PCV hose from the TB though

I'm positive it's not the TB being ajar, I checked and there is no tension from the linkage, so unless the TB itself is not good (highly unlikely) that's not the issue

As far as timing, i did jumper the diag box but now that I think back, I'm not sure it made good contact. Don't really think it matters because I can't set timing properly until I get my idle down to spec...

Thanks jetjock!

 

[Jaguar_5]

When I pinch the ISC and TB PCV hose the engine almost dies, but not quite... I'm not sure If I'm just not able to completely pinch off the ISC hose with my fingers or If this does mean I have a vacuum leak

All the hoses are brand new, I really hope it's not an intake manifold gasket or something like that

 

[Jaguar_5]

BOV normally doesn't provide an idle air path around the throttle plate. Pinch off the idle hose and the PCV line going into the TB. Engine should die. If not there's either a pirate air leak somewhere or the throttle plate is cracked open. If the engine dies check the ISCV and reset timing with the diag block jumpered.

If I spray carb cleaner into the open BOV, the idle does go down, so I think this is my problem

If I adjust timing with the jumper in, even though I'm just under 1500, I couldn't get it down to 10*, it's at like 30 or something rediculous, not sure if this is because of the RPM's or what... but when I set my timing initially, It ran really rough until I moved it 1 tooth, so I don't know If I need to move it 1 more tooth but I think that will be too much I don't remember which direction I had to adjust it last time either...

Definitely not going to pass emissions like this! I'm struggling to find anywhere else that the air might be entering other than the BOV, does this mean my TB isn't sealing?

Oh, and unplugging the ISC during idle did nothing, I don't think I heard the ISC click when I shut it off, but I don't have someone to shut it off while I can listen from the engine bay

 

[Jaguar_5]

Update:

Plenty of suction from the ISC hose, plugging it brings idle down, almost no suction from PCV hose, doesn't do much plugging it

Took off my upper IC pipes, the TB sucks in air like CRAZY! The butterfly valve is completely closed though, there's a huge amount of vacuum coming from the hole in the top of the TB, plugging it quickly kills the engine, i was able to slowly restrict it and cap it and the engine barely ran

 

[jdub]

Are you talking about the PCV port on the TB?
(the hole in the top of the TB)

You're not going to be able to set timing with an idle that high.

 

[Jaguar_5]

Are you talking about the PCV port on the TB?
(the hole in the top of the TB)

You're not going to be able to set timing with an idle that high.

That would be it, the hole at the top before the butterfly valve, on the inside... If I plug it, it kills the engine

If I plug the outside of the TB, where the PCV hose connects, there is no suction, nothing happens

I'm not worrying about timing until I get this sorted out

I'm almost considering putting things back together and just plugging the ISC hose just so I can pass emissions lol

 

[jdub]

That would be it, the hole at the top before the butterfly valve, on the inside... If I plug it, it kills the engine

That hole is what supplies vac to the EGR, not the PCV...check your lines to the EGR VSV and VSV itself.
There should be no vac on that line (or hole) with the TB plate closed. I suspect you have the small 90 deg fitting on top of the TB that connects to that hole misrouted.

 

[Jaguar_5]

When I disconnected the two vac hoses (which I'm pretty positive are hooked up correctly) nothing changed, there was no vacuum coming from the two fittings on top of the TB

I am pretty sure my PCV passage in the TB is clogged... I am draining the coolant to take off the TB

 

[jdub]

How about from the hose that attaches to the fittings?
Block them off and see what happens.

The PCV routes to the back side of the TB, just below the flange. There is no way it could pull vac on the small hole in the throat of the TB. The PCV fitting could still be clogged, but it can not do what you described.

 

[Jaguar_5]

How about from the hose that attaches to the fittings?
Block them off and see what happens.

The PCV routes to the back side of the TB, just below the flange. There is no way it could pull vac on the small hole in the throat of the TB. The PCV fitting could still be clogged, but it can not do what you described.

You mean If I plug the vac hoses that plug into the TB's nipples? I believe I tried that and nothing happened...

Everything is taken apart now so I can clean it out with my air compressor, I'll try again when I put it back together

Really running out of ideas, this doesn't make sense to me!

 

[jdub]

Now that you have it apart...clean the PCV with carb cleaner. Then blow it out. Check for air flow to the opening at the flange. (won't be much, there's a orifice in the PCV channel)

 

[Jaguar_5]

The vacuum is coming from the other side of the butterfly valve, at the port in the upper left corner (opposite of the PCV port)

Could this mean the previous owner had played with the Idle air screw? Could this and a bad ISC be the cause of my problem?

I can see some light escape through the butterfly valve, pretty minuscule though.

My PCV is completely plugged, air compressor can't even clear it out!

 

[jdub]

Ok...which line is the vac coming from in this pic and check the routing:

 

[Jaguar_5]

Sorry if I mislead you, what I meant was the port I was blocking off earlier at the top of the TB in the inside, leads to (gets it's vacuum from) the port on the other side (intake side) of the butterfly valve, inside the TB on the upper left corner (the PCV get's is vacuum from the one in the upper right corner, as you were talking about)

It seems like it's the idle control screw on the side of the TB (I know not to touch it) letting too much air around the butterfly valve?

That picture is exactly how I routed my vacuum lines, It was my guide

 

[jdub]

Before you look at the screw, how did it idle with this TB before the rebuild?

There's a vac lne that runs from the bottom of the metal "tree", to a fitting on the head, to the fitting on the front hardline on the 3000 pipe. Is it connected correctly. (iirc it's the one to the BOV).
Previously, did blocking the line from the BOV have any effect?

 

[Jaguar_5]

Before you look at the screw, how did it idle with this TB before the rebuild?

There's a vac lne that runs from the bottom of the metal "tree", to a fitting on the head, to the fitting on the front hardline on the 3000 pipe. Is it connected correctly. (iirc it's the one to the BOV).
Previously, did blocking the line from the BOV have any effect?

I already messed with the screw, it was backed pretty far out. I counted the number of turns, its now about 1 rotation out from all the way in, and instead of flowing freely, there is some restriction when I blow compressed air in the port

My PCV port is officially clogged, looks like I'll need a new TB in the mean time will this cause any harm to my engine? Or will venting into the accordion hose be enough?

I have no idea how the car idled, I bought it as a project and I've never seen it idle.

I'm pretty convinced it's a combination of the air screw and a faulty ISC (i hear no clicking after shutoff)

As far as the hose that goes to the BOV, if I block it off, it kills the engine (I only tried it when my upper IC pipes were off)

 

[jdub]

The PCV need vac from the TB. When you're looking for a leak like this all the parts need to be in place (i.e. IC piping). You don't want to induce a vaiable that's not there during normal ops.

You can test the ISCV...failure is not common on these. Did you take it apart and clean the carbon off the valve plunger and seat?

 

[Jaguar_5]

The PCV need vac from the TB. When you're looking for a leak like this all the parts need to be in place (i.e. IC piping). You don't want to induce a vaiable that's not there during normal ops.

You can test the ISCV...failure is not common on these. Did you take it apart and clean the carbon off the valve plunger and seat?

I was trying to determine if the TB itself was leaking, that's why i removed the IC piping

So without the vac from the TB for the PCV i can cause damage?

I will put everything back together, If I need to test the ISCV i'll have to order a new gasket first, you actually ceramic coated it (or swapped mine out for a ceramic coated one) and I got a new check valve from Toyota, the only reason I'm suspect is not hearing the clicking after shutoff.

Thanks for all the help, I really appreciate it!! I'd be lost without SupraMania!!