need vac diagram for removing secondaries

[bradley]

for a 1990. I want to keep the cruise control. Ihave read the threads but I guess I am old and get confused easily . could someone draw it out for me . for example do I keep the port throttle solenoid with the3 connector attached ???? do I have to run vacuum to the map sensor under the computer ?????? I just don't want to do the wrong thing .

[Paul Workman]

Hello Bradley!

Lone Pine, CA eh? Been there many times - lived in San Diego for 12 years.

Two approaches:
The "temorary" method: Tie the secondary port throttles open so it can easily be reverted to stock at a later date.
Or, gut the entire system. (Note: either method is reversible, unless the secondary runners are to be "ported" such that the throttle plates will no longer fit.)

On a 90...



Whichever method you choose begins with having a chip in hand that is programmed for the secondary delete option. (I got mine from Marc Haibeck, but Greg Vandeventer (sp?) and others too can provide you with one.) More on that later...

To simply tie the throttle plates open, everything may remain intact except the vacuum pump and the vacuum solenoid switch (under the plenum) wire connections and the vacuum line to the MAP switch. (On a 1990 it is located (attached) to the underside of the ECM. The vacuum line is replaced with a foam nipple to keep dirt out.)

Gutting the secondaries and all the hardware involves removing everything in the diagram that is highlighted in pink (see diagram) and capping off the plenum vacuum port on the driver's side (only). (The passenger side vacuum port is left connected to control the rest of the sundry systems.) Also, gutting the system will require you to press in a Dorman #555 freeze plug into the now empty bearing port, and sealing it with (I used JB Weld).

The FULL POWER select switch must always be in FULL POWER as long as the secondaries are removed or tied open. The chip calibration splits the fuel delivery between the two injectors, and if that switch is not closed (FULL POWER mode) for any reason, HALF of the fuel is cut off, resulting in an extreme LEAN condition. (I jumpered (hard-wired) the switch against human or mechanical influences.) Note: The 91+ cars the switch is latched within the ECM programming.

FWIW, I gutted my secondaries 5(?) years ago, and NEVER looked back! To revert it now would require custom throttle plates (runners are now ported), and result in a return to throttle hesitation, carbon build-up on the secondary valves, and the headaches of maintaining the system.

You'll love it! Good luck.

[Dynomite]

Originally Posted by bradley

for a 1990. I want to keep the cruise control. Ihave read the threads but I guess I am old and get confused easily . could someone draw it out for me . for example do I keep the port throttle solenoid with the3 connector attached ???? do I have to run vacuum to the map sensor under the computer ?????? I just don't want to do the wrong thing .

I am not a good drawer.....so I take photos.

You MIGHT want to also eliminate TB Coolant

Starting at Item #2 (Eliminating Secondary Throttle Vacuum system) See LT5 Eliminated Systems
.

There are two vacuum sources (Electric Vacuum pump and Plenum).

Remove everything except the diagnostic vacuum sensor that is located under the ECM. The sensor is connected electrically and the hose nipple open to the atmosphere. Remove all of the vacuum lines, the Secondary Vacuum Reservoir, the solenoid valve and the electric vacuum pump. Use Marc Haibeck CHIP's Marc Haibeck

Secondary Vacuum System


Diagnostic Vacuum Sensor


There are two vacuum check valves under the plenum (one connected to HVAC tank and one connected to Secondary vacuum reservoir). The check valve connected to HVAC tank (via the "Y" cited below for Eliminating Air Induction System) remains in position connected to passenger side source of plenum vacuum and connected to the HVAC vacuum line in the harness to rear of plenum.

The check valve connected to the Secondary Vacuum Reservoir and drivers side source of plenum vacuum can be capped off since the Secondary Vacuum Reservoir is eliminated. This is shown in the Eliminating TB coolant system picture below.

3. Cruise Control/HVAC and EVAP Purge System.

The Cruize Control/HVAC Vacuum is taken from the passenger side of plenum. From there one vacuum line goes to the Cruize Control under ECM/Brake Cruize Vacuum Release (one line) and the second line goes to the HVAC System through the passenger side Fuel Injector Wire Harness (second line). The Vacuum line to the Cruize Control includes the Cruize Control Vacuum Reservoir under Drivers side Headlight which is left in place. The other vacuum hose connected to the Cruize Control is for the brake pedal cruise cancel function.

The EVAP Purge system (1991 ZR1) draws vacuum from under front of Plenum and through the Solenoid valve. When the Solenoid valve is activated, vacuum is directed out the right side under Plenum back along the passenger side frame rail to the Charcoal Canister directly behind the Passenger Side rear wheel. The 1990 ZR1 Charcoal Canister is located under the Drivers Side Headlight. (Vacuum for the 1990 Charcoal Canister is taken from the drivers side front of Plenum as well as a vacuum line from beneath the front of the Plenum. See Vacuum Systems 90' and 91' (Secondary and Cruize/HVAC)

Cruize Control and HVAC Vacuum System .....................EVAP Purge Vacuum System (1991) with Solenoid


Marc and Pete suggested to eliminate the EVAP Purge circuit completely and capping off that vacuum source under front of plenum. I just replaced my charcoal canister and Marc says he does not address that removal in the chip as it has no effect. I left that associated vacuum and electrical connection including the Evap Purge solenoid in place under the plenum.

This discussion and photo is for a 1991 which has the Charcoal Canister just to the rear of the passenger side rear wheel. The 1990 has the charcoal canister under the drivers side head light so the Vacuum Connections for Charcoal Canister are different as well as the vacuum lines which for the 1990 you will not find the large loop for charcoal canister under the Plenum. You will find the Plenum Nipple (Purge Vacuum Connection) on the 1990 is straight out of the plenum rather than angling back under the Plenum. On a 1990 you will also find a vacuum nipple angling back under the plenum from the Air Horn which provides vacuum depending on throttle position to the Purge Canister Control valve under the Drivers Side Head Light (1990 only).

[bradley]

I got the prom from corey . we still have the port throttle solenoid hooked up should that be taken out also as we now have a code 61 . we pulled the secondary plates and used the doorman plugs to b lock .why code 61