Secondary Air Cleaner and EGR Delete

[adamboggs86]

I recently bought one the HKS downpipe flanges because I've been wanting to go catless. I understand how to remove like the air cleaner box itself, but rerouting the vacuum lines has me very confused. I've tried reading through the forums to find pictures, but majority of the links are dead. Could someone explain or send a diagram of where to reroute all of the vacuum lines when removing the secondary air cleaner and EGR? Thanks in advanced.

[TSITy]

The only vacuum line you need to have the car running is the one to the distributor. All the others are "extra". Though, you'll want to keep the one by itself on the bottom going to the cabin if you want your vents to actuate. It all depends on what you want to keep.

[kev]

You need to retain your fuel vapor purge valve functionality unless you are removing that purge valve completely and letting it always vent to atmosphere (I wouldn't recommend).   The thermo valve is also used for purge valve functionality but it can be removed without any real issues....it just keeps the purge valve closed until the engine warms up.    So, you need the two lines running across the front of the engine to the purge valve under the air can (one black, one blue stripe).  You need the black line to the dissy vac advance.   You need the lower line on the intake running to the cruise control system and interior HVAC.    And that is about it.   Oh, and the line from the fuel pressure regulator to the injection mixer body....but I don't believe this is on the vac diagram.   And if you have an 88/89, there are a few lines for the wastegate...which typically were removed many years ago by former owners.  

Open up the vac diagram in the FSM (Page 25-3, or 25-14 or 14-3) and, using this information, it is pretty easy to determine what can be simplified.   Port D on the TB will have a black line going to a T (one leg to the dissy vac advance, other to the purge valve top port).  Port A of the injector mixer will go to the side port on the purge valve.   If you want to retain the thermo valve (meaning your plastic ports are not cracked on it), then leave it in (it taps into the same black and blue stripe lines, as seen in the diagram).   Just make sure all open lines and ports are capped...especially Ports E and M on the TB (Port M is the perfect spot for an aftermarket boost gauge.  Page 14-31 gives the port nipple locations on the injection mixer/TB.  The FSM does a good job explaining the functionality of each component as well.  

[adamboggs86]

Kev that’s the most in detail explanation I’ve gotten so far I appreciate that. Could you send me some pictures of all of your vacuum lines you have routed and anything you have plugged. I think I understand, but I like to have pictures to make sure I’m doing everything right. 

[kev]

Perhaps, but it won't be this week...for I am not able to access the car at the moment.    I think I explained it in detail enough.  Print out that vac diagram and just start crossing out the things you are removing.    Cap everything that is still can have a vacuum leak.   The only thing you wouldn't cap is for the wastegate solenoid on 88/89...you would connect the line from your OVCP to one of the two front ports of the wastegate actuator and plug the port next to it.  Leave the rear port open to atmosphere.    Besides this one case, conservatively cap everything if you are unsure!

[admin_JAinsworth]

The Diagram
 
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The list of ports (22 in all)
 
1. Vacuum Retard Diaphram (directly on top of the distributor)
2. Top Port on the TB, right where the OVCP meets the TB
3. Secondary Air Cleaner Assembly (black box on the drivers side of the VC)
4. Thermo Valve (2 ports)
5. EGR (3 ports)
6. SACA Solenoids (5 ports)
7. Main Vacuum source (3 ports)
8. Bottom port, this feeds the vac storage, cruise, and runs to the vac pump in front
9. Vacuum Storage (not pictured), mounted to the side of the shock tower
10. Cruise Control (not pictured), mounted to the front of the shock tower
11. Vacuum pump (not pictured), mounted right beside the drivers headlight  
12. Purge Control Valve (2 ports), directly under the aircan
 
Now, depending on what you're wanting to do with your car, your position on the environment, and whether or not you need a smog test to get a state inspection, it's possible to remove some of the vacuum lines and clean up the engine bay a LOT.
 
For a pure race car you'd probably just need 1 stock line (slightly relocated), that'd be a line running from the top of the TB (labeled #2), to the Vacuum Retard Diaphram (labeled #1), this is the only line that is an absolute necessity.  However, if you want, for example, your inside head & foot vents to work properly, you'll need to keep the line running from the bottom of the TB (labeled #8 ) going to the Vacuum Storage canister (labeled #9) (+ the single, small vacuum line running from it's nearest "T" into the firewall [not pictured or labeled]).
 
Since this comes up frequently I'll address it here, the vac port you use for a BOV is labeled Main Vacuum Source (#7), you'll use the one closest to the firewall if you're looking at it from the drivers side fender.
 
If you need a smog test to pass a state inspection you'll probably need to keep everything, each vacuum assisted item has its place.
 
If you've removed the catalytic converters you won't be needing the Secondary Air Cleaner Assembly (labeled #3), it supplies fresh air to the catalysts.
 

 

[LizardKing]

Now that's a gold nugget of information right there!!!!!