7mgte vacuum specifics

[easternguy2005]

I'm trying to get the vacuum hoses right on my USA 1990. The diagram is great but I don't understand a few things.

1-The EGR vacuum modulator has 2 vacuum lines (plus one bigger hose on the bottom that goes to the EGR valve). Does it matter which nipple goes to either vacuum line ? Could you swap the hoses on the nipples without any difference ?

2-The stock boost controller has a long vacuum hose off the black box on the fenderwall but where does that hose plug in ?

3-The heater hard line along the firewall - where does that get its vacuum from ?

4-In this picture does this plug into that long bronze looking nipple on the rear side of the intake manifold ?


Thanks for any suggestions. I really want to get these hoses right before I start it up tomorrow.

 

[jdub]

I'm trying to get the vacuum hoses right on my USA 1990. The diagram is great but I don't understand a few things.

1-The EGR vacuum modulator has 2 vacuum lines (plus one bigger hose on the bottom that goes to the EGR valve). Does it matter which nipple goes to either vacuum line ? Could you swap the hoses on the nipples without any difference ?

Better pic:

The line needs to be routed from the EGR VSV to the appropriate nipple on the modulator as shown to supply vac to the correct side of the diaphragm inside it.

2-The stock boost controller has a long vacuum hose off the black box on the fenderwall but where does that hose plug in ?

3-The heater hard line along the firewall - where does that get its vacuum from ?

4-In this picture does this plug into that long bronze looking nipple on the rear side of the intake manifold ?

This pic kinda shows it:

All these have the same answer...the fitting on the back of the manifold supplies vac to the gauge boost sensor, cruise control, and heater VSV. My manifold nipple goes into a 4-way fitting with lines leading to the above.

Thanks for any suggestions. I really want to get these hoses right before I start it up tomorrow.

Very good idea

 

[easternguy2005]

Thanks for the fast reply Jdub.

How can I tell which side gets which hose ? The only marking on the modulator is the letters "ND" in a circle stamped on the housing. However one side is much harder to suck on than the other. Put that side on the vacuum side ?

My goal concerning the other items should be then to provide vacuum to everything from a 4 plug connector coming off the intake manifold so all these items (egr, boost, heater hardwire, cruise) have the same vacuum.



Sidenote - Just noticed that the bottom hose is broken. I couldn't tell by looking at it because there is a fabric cover over the hose. When I was holding it I could feel that it was soft right next to the clamp on the modulator. I'll get some silicone hose tomorrow for that.

Attached a pic of the EGR modulator - The NG logo is on the bottom. Both ends are the same length.

 

[jdub]

You know...I had a brain fart
It really doesn't matter which side the vac lines are on...the modulator is a flow valve. I was thinking the EGR valve itself...not the case here. For what it's worth, mine has the side you are holding going to the valve, the other side (right in the pic) goes to the VSV.

I would get a hose from the dealer for the connection to the EGR valve...it gets hot from exhaust gas.

 

[easternguy2005]

If I put this into the vacuum line then it's just gonna lose vacuum. There must be a difference because one side will act like a open hose and the other doesn't. I took the cap off to check the filter and there is a Letter "P" on one nipple and the letter "O" on the other nipple under the cover.

If I had a spare I would take this apart

 

[jetjock]

I think you mean Q, not O...and it does matter.

 

[trydrew]

I think you mean Q, not O...and it does matter.

Mhm...


http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EC&P=18

 

[easternguy2005]

Yes, looked again and that is a "Q" indeed.

The hose connecting the EGR valve to the modulator has never been connected yet the car didn't throw a 71 code.


added:
Yeah the TSRM doesn't specify which one either (notice the "reconnect hose to proper location on the previous page) however the label on the hood does and I had to remove the cap to find the letters. It really must matter because both sides appear to be independent and one side will induce a vacuum leak while the other wont. The Q side is free flowing through the vent where the "P" isn't. The label specifies the Q going to the EGR valve where. The P goes to the solenoid controlled VSV.

Thanks for the help - I'm ready to connect it pending that hose connecting to the EGR valve.

Jdub has it right - the logo on the bottom, the left side (Q) goes to the valve.

 

[jdub]

I just told you the way mine was hooked up...glad it was correct
It appears it does matter.

I was under the impression vac was modulated depending on exhaust back pressure applied to the bottom (braided) fitting. The top ports look like it was a straight through design with a center valve regulating flow. I based it on the diagram on page 3 here:
http://www.autoshop101.com/forms/h61.pdf

BTW - Code 71 exists only on CA cars and it's for low EGR gas temp when the EGR is suppose to be functioning.

 

[easternguy2005]

Got it together. Car started fine when cold and idled fine. Once it got warm it was "lobing" and rich as all heck. Figuring a vacuum leak/misconnect or leak in manifold. All turbo to manifold pipes tight and no codes either. I'll check it out in a few days when I feel refreshed. Runs good at 3K rpms but the idle is horridly up down, up down in the 400 to 800 range and slowly steadies itself only to start it again.

What's still confusing to me is the metal pipe bundle under the manifold. Does anyone have a picture of that connected with the motor out ?

 

[3p141592654]

Not that it matters anymore, but the EGR mod should have a sticker on it with P and Q clearly marked.

 

[easternguy2005]

That explains alot actually why I couldn't figure it out.

 

[easternguy2005]

Finally tracked every line down. Blow in one end and look for the other in that metal pipe area area by alternator so got them all right. The idle up and down was the two bolts that attach to the intake manifold for the EGR valve. Found it spraying carb cleaner.
Runs perfect now after fixing that leak.