Tech Info - LT5 Eliminated Systems
 

Tech Info - LT5 Eliminated Systems
The LT5 runs perfectly with all that is eliminated described here.
Marc Haibeck has addressed all items in a modified Low 87 Octane and a High 91 Octane Chip.

1. Eliminating Secondary Throttles/shafts.

Install Dorman freeze plugs 555-108 with Loctite 262 to plug the secondary shaft ports for a complete elimination of Secondary throttle shafts and associated vacuum canisters (90 Heads on Left and 91 Heads on right) .

http://i287.photobucket.com/albums/l...psc34c519c.jpghttp://i287.photobucket.com/albums/l...ps00ee9dfe.jpg

2. Eliminating Secondary Throttle Vacuum system.

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
http://i287.photobucket.com/albums/l...yVacuumSys.jpg

Diagnostic Vacuum Sensor
http://i287.photobucket.com/albums/l...cuumsensor.jpg

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
http://i287.photobucket.com/albums/l...5252a35535.jpghttp://i287.photobucket.com/albums/l...3761fafa4e.jpg

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).

http://i287.photobucket.com/albums/l...edbdeff335.jpg

4. Eliminating Throttle Body (TB) Coolant system.

See this link for TB Coolant Blocking drilling and threading details Injector Housing TB Coolant Blocking

Install 1/8 inch NPT allen head pipe plugs (21/64 or 11/32 drill) two each side of Plenum (Two each TB Coolant and Injector Housing (IH) Coolant) as shown (The associated two IH coolant ports in the IH should also be plugged on each side). Total six coolant ports plugged One each side TB, One each side Plenum, One each side Injector Housing.

Or as you like....just install the two 1/8 NPT Aluminum pipe plugs in the Injector Housings as shown.

Photo by Ccmano
http://i287.photobucket.com/albums/l...55797df488.jpg

Remove Plenum and Block TB Coolant at Injector Housing (LT5 will have TB Coolant Blocked but Undetected and engine appears stock). This will require you insert a plug in the Coolant Return Line on the Passenger side of the Plenum (the only TB Coolant Hose that requires a hose clamp).

http://i287.photobucket.com/albums/l...5c16de2400.jpghttp://i287.photobucket.com/albums/l...4dba854f45.jpg

See Summit Racing 1/8 inch Aluminum Pipe Plugs for Aluminum Pipe Plugs. When you install the plugs.....keep trying the plugs as you tap to make sure the final installation is about flush or out 1/16 inch and use Permatex on the plugs.. The Injector Housing Plug must be FLUSH however.

Remove TB Coolant hose and tubing left and right side of plenum and plug hose return to coolant tank passenger side See Brass Cap just above the "T" on Passenger Side. Initial Coolant Fill may be somewhat affected by the TB Coolant Elimination (see item #4 Initial Coolant Fill). The "T" connects the top of the radiator Air Vent, TB Coolant Return, and Coolant Reservoir in front of Passenger side. With the TB Coolant Return Blocked, what is left is a coolant line from the Radiator Air Vent to the Passenger Side Coolant Reservoir. See (Filling With Coolant and the Air Locked Water Pump) for Detailed New Coolant Filling Trick.

http://i287.photobucket.com/albums/l...bcc89d832c.jpghttp://i287.photobucket.com/albums/l...666a77e43d.jpg

A brass nipple that fits tight inside the rubber hose with a male 1/4 inch pipe thread and a 1/4 inch Brass pipe thread cap (female thread) ;)

I left about 2 or 3 inches of rubber hose above the "T" that connects (did connect) the TB vent, Radiator top vent, and Coolant surge container in front of passenger side (the highest point in the LT5 Coolant System).

Note 1: The TB coolant path back to the passenger side overflow tank does provide a path for air and potential air lock to return to that passenger side tank during initial coolant fill. However, the Plenum to TB coolant hose sits only an inch or so above the IH coolant manifolds on the passenger side so the benefit of using that path to bleed air vice the top of the coolant manifolds to the radiator is very small. Marc has decided to bypass the TB coolant (vice eliminate all TB coolant hoses) leaving that coolant path back to the passenger side overflow tank in place to assure issues would not arrise on rebuilds for those unaware of coolant initial filling and water pump potential air locks.

Note 2: Air Pockets as a result of TB Coolant Elimination Tricks. See (Filling With Coolant and the Air Locked Water Pump) for Detailed New Coolant Filling Trick.

The 5th plug (Plenum Vacuum) is for Plenum Vacuum drivers side only which was connected to the vacuum reservoir. The tubing can be removed and a 1/8 inch NPT allen head pipe plug inserted exactly like the plenum coolant plugs.

a. When you run the tap....keep checking the pipe plug for depth so you end up tight and flush.
b. When you run the Drill.......remember you are in ALUMINUM so go very easy and slow!!! (you can do it without a drill press).
c. Use a bit of Permatex gasket sealer or Teflon tape on the pipe plugs.

http://i287.photobucket.com/albums/l...enumblockN.jpg

5. Eliminating Air Injection system.

The Air Injection System including the Air Pump has been eliminated (especially for those who are installing Headers). Associated with the Air Injection system is one vacuum line on the drivers side fender skirt above the shock tower. I eliminated the "T" and just moved the "Y" in front of "T" about 3 inches and plugged the "Y" back in where the "T" was. This modification maintains the Cruise Control Vacuum and the associated Vacuum to the Cruise Control Vacuum Reservoir under the Drivers Side Headlight.

http://i287.photobucket.com/albums/l...rInduction.png

6. Eliminating Positive Crankcase Ventilation (PCV) Pipe and added Oil Catch Can.
See Details for Oil Catch Can Installation

The PCV pipe along the plenum drivers side from PCV valve at rear of Plenum to Plenum Vacuum at front of Plenum eliminated. Stainless steel braided hose is used from the PCV valve at rear of plenum to Oil Catch Can (LT5 Added Systems) and then on to the Plenum Vacuum.

The PCV hose connected under front of plenum (Vacuum source) is connected using SS braided hose to an Oil Catch Can external to the engine which Oil Catch Can is connected to the dual PVC valves hard line located at the rear of the plenum. The MAP sensor (located at rear of plenum) is connected to the rear of plenum (Vacuum source).

7. Eliminating Stock Exhaust (installing SW Headers).

SW Offroad Headers. As you know it is difficult to install headers with LT5 in the ZR1. With engine out I was able to install 14 of the 16 header bolts with locks (on each Header) in just a few minutes.

Installing the the LT5 with Headers Installed is easy if the LT5 is tilted to the rear considerably. The LT5 has to be prevented from rolling from side to side. Leave the Fuel Rails, Plenum, and Bell Housing OFF untill after the LT5 is installed in the ZR1.

1. You definitely need a load leveler (to UNLEVEL or tilt the LT5 to the rear).
2. You CANNOT use the standard lift eyes for the LT5 because as you load UNLEVEL (Tilt engine to the rear) the engine rotates if you lift LT5 on diagonals.
3. You have to lift with nylon straps around Flywheel (rear) and around Harmonic Balancer (front). Actually around more stuff on front.
4. You have to remove the A/C Temperature sensor cover (passenger side firewall) and Wiper Motor (Drivers side firewall).
See How to Replace the Wiper Motor.
5. You DO NOT have to remove the hood and the ZR1 can sit on the level.

A/C Temp Sensor........................Wiper Motor.............Do NOT use standard Lift Eyes installing LT5 with Headers
http://i287.photobucket.com/albums/l...b831693bc3.jpghttp://i287.photobucket.com/albums/l...fb79829124.jpg
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Installing Headers
Installing Engine In ZR1
Lifting The LT5

Last UPDATE of post 1 Dec, 2014

Tech Info - Marc Haibeck on LT5 Eliminated Secondaries and Associated Anomalies
 

Tech Info - Marc Haibeck on LT5 Eliminated Secondaries and Associated Anomalies

Marc Haibeck has a Custom Chip for the elimination of the Secondaries
as well as Custom Chips for any Year and Modification on the LT5. Marc Haibeck Chips/Custom Calibrations

A. Marc Haibeck mentioned to me some time ago....Haibeck Automotive Technology
Removing the secondaries is not a bad idea.

Marc dyno tested removing the secondary throttles and found no significant changes.

Marc suggested there are three situations where removing the secondaries are useful.
1. If you are having a problem with them that you can't fix, they can be eliminated.
2. If you can't find a repair part.
3. If you have removed them to port the heads, you can save time and not reinstall them.

Marc also mentioned that removing the secondaries does not effect the idle, fuel economy or torque over 1500 rpm. Having the secondaries in place might be an advantage for an emission test. See item C below.

Further, with the elimination of the secondary port throttle control the engine idles on the primary injector only. When the main throttle is opened to about 1/2% or more the secondary fuel injector activates. This usually happens while the clutch is being slipped to drive away, typically the engine is running on both fuel injectors before the clutch fully engages. Once the throttle is more than 1/2% open the flow split between the primary and secondary injectors is the same as the OE value of 50%-50% and in sync with each other.

I might also mention eliminating the associated vacuum system and secondary cannisters gets rid of a lot of potential failures later on and makes for a clean looking LT5 installation.

B. Eliminating the air injection system may have ramifications in regard to a SMOG check depending which State you reside. I have also eliminated the original Exhaust Manifolds and CATS which would be required in some States for SMOG check success.

C. The Role of the Oxygen Sensor causing Hesitation issues unrelated to the Haibeck Chips or Elimination of Secondaries.

Marc ran into an anomaly associated with Oxygen Sensors that may cause Hesitation related to fueling.

RockAuto Bosch 13077 Oxygen Sensors
Jerry's Oxygen Sensors

Engine Hesitation with Haibeck Chip TIPS

Last UPDATE of post 2 Oct, 2014

Tech Info - LT5 Added Systems
 

Tech Info - LT5 Added Systems

Note the Gun Metal Oil Cap on passenger side.
Ebay Aluminum billet oil cap (fits 90' & 91' LT5 & L98)
May require dressing up the threads just a bit with a file but the threads of the cap are the same.

http://i287.photobucket.com/albums/l...T5/Blingzz.jpg

Items 1 - 6 are Added to ALL engines.

1. 91' ZR1 (LT5) Debree Screen.
Use 1/8 inch steel pop rivets with washers backside of air deflector and on front of screen
(approximately 5/16 inch mesh). Drill 1/8 inch holes in the rubberized air deflector.
Use cable ties on top side of screen.

http://i287.photobucket.com/albums/l...R1screen-1.jpg

2. Differential case drain installation
Installed an aftermarket Differential Case Drain Plug for easy fluid change.
The kit is available from Corvette Central

http://i287.photobucket.com/albums/l...CaseDrain3.jpg

The kit provides a template that puts the hole just left of the center bolt in the valley of the differential.
Original Photos provided by Scrrem on another topic with Red notes added.

http://i287.photobucket.com/albums/l...eDrainTap3.jpghttp://i287.photobucket.com/albums/l...eDrainTap2.jpg

The tap size is 1/8-27 pipe and it installs easily with drill (11/32) and tap supplied in the kit.

I drilled the bottom flange just under the ring gear and let the old fluid drain (which drained in about 10 minutes). I then tapped the drilled hole for the 1/8 inch allen pipe plug. When you tap the hole, try the pipe plug several times as you tap so you end up with the pipe plug out maybe 1/16 inch when tight .

I pumped in a pint of Mobile 1 75W-90 and let that drain cleaning out a lot of old oil and any tap debris. 1/8 inch Aluminum Allen Head NPT pipe plugs

I inserted the 1/8 inch allen pipe plug and pumped in a bit over 3 pints of Mobile 1 75W-90 into the fill port on the North side of the differential (Z facing West)

The Differential case can be COMPLETELY drained and flushed with new oil using this method as compared to trying to suck out the old oil.

3. PCV Connectors.
In addition to the Oil Catch Can, new PCV dual connectors have been added replacing the old connectors.

Jerry's Dual PCV Valve Connector
Jerry's Dual PCV Valve Connector Hose
Jerry's Dual PCV Valve Connector Grommet

I installed Jerry's New Dual PCV Connectors on ALL engines getting rid of all the Clap Trap Nylon Ties and Hose Clamps to keep the Old (hardened Rubber) Dual PCV connectors from slipping off the PCV valves/lines or leaking Highly Recommended :thumbs:
Right up near Top Of List with Blocking TB Coolant at each Injector Housing.

http://i287.photobucket.com/albums/l...a48835bce4.jpghttp://i287.photobucket.com/albums/l...1cd951b2e6.jpg
http://i287.photobucket.com/albums/l...4769bcd3e7.jpg

Along with the PCV Upgrades is the raised Plug Wires from Injector Housing Bolt to Plenum Bolt on ALL engines. This allows the Dual PCV Connector to be attached in front of and at the same location as the Plug Wires and above the Cam Covers A Very Clean Installation lifting the Plug Wires OFF the Cam Covers.

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4. Starter Relay Tricks Starter Relay, Wiring Harness, and Plugs Tricks

See Item #2 Electrical Ground Connections and Installing Starter Relay

60 / 80 AMP RELAY SPDT SINGLE POLE DOUBLE THROW NEW 654
Installed under ECM and in slot between brake booster and fire wall (perfect place for location of Relay).

Wiring modified a bit to assure Pin #87a is not hot at any time.
Pin #30: Purple wire to starter (use 3/8 inch connector on relay).
Pin #87: Red wire battery positive 12v use 3/8 inch connector on relay (connected to battery positive multiple connection post).
Pin #86: Battery ground (1/4 inch connector on relay connected to ground where battery 12 gauge wire grounded).
Pin #85: Purple wire from ECM use 1/4 inch connector on relay (Red wire on early 1990 ZR-1).
Pin #87a: Not hot at any time and not used.

http://i287.photobucket.com/albums/l...T5/Relay-1.jpghttp://i287.photobucket.com/albums/l...arterRelay.jpg

Insert a short 1/2 inch long section of plastic hose
over the center connector on the Relay which is NOT
used in this application.
http://i287.photobucket.com/albums/l...21643f629b.jpg

5. SS Braided Oil Cooler Lines

See SS Braided Oil Cooler Hoses and Fittings

http://i287.photobucket.com/albums/l...9da1d9d690.jpg

6. Billet Aluminum Ultra Light Belt Tensioner Pulley
This Belt Tensioner Pulley will fit the ZR-1 (LT5) as well as a standard C4 with L98 engine.
Ebay Billet Aluminum Belt Tensioner Pulley

http://i287.photobucket.com/albums/l...inumPulley.jpg

Belt Tensioner with High Speed Idler Pulley...............Diameter of Billet Aluminum Pulley is
Use Red Loctite on Pulley Bolt......................................3/16 inch larger than stock pulley
http://i287.photobucket.com/albums/l...d776536bdf.jpghttp://i287.photobucket.com/albums/l...af4128c4bc.jpg

Hand File Small Bevel around diameter of outer ...........Pulley is placed on Belt Tensioner with pulley
Collar to clear bearing Snap Ring.................................bearing Snap Ring facing Collar (Forward)
http://i287.photobucket.com/albums/l...bb55da7d8a.jpghttp://i287.photobucket.com/albums/l...e5a2762d8d.jpg

Close up of minor modification of Belt Tensioner Flange
http://i287.photobucket.com/albums/l...3596af4add.jpg

The amount of pressure on the belt depends on belt length and compression of the Belt Tensioner itself. You want enough slack to get the Belt over the Alternator Pulley when Belt Tensioner is fully compressed using a long 1/2 inch Socket wrench. You can start the compression process of the Belt Tensioner by using a heavy Broom Handle compressing the Belt Tensioner so you can engage the socket in the Belt Tensioner socket 1/2 inch socket hole provided. This Billet Aluminum Belt Tensioner Pulley will give you just a bit more belt tension given the pulley is a bit (1/8 inch more or less) larger in diameter than a stock pulley.

As an aside......After removing the Serpentine Belt, remove the Belt Tensioner Bolt and Washer. Get hand under passenger side coolant manifold in front of alternator pulley and grab hold of Belt Tensioner Pulley. Lift Belt Tensioner up and sideways through slot under coolant manifold/Radiator Inlet Pipe (Passenger Side) while lifting coolant Radiator Inlet Pipe (Do NOT disconnect any coolant hoses). Use Red Loctite on Belt Tensioner Pulley Bolt.

Items A, B, and C are Added to Some Engines.

A. Oil Catch Can has been added.
See Details for Oil Catch Can Installation

-=Jeff=- was one of the first I think Oil Catch Can Photo

The PCV hose connected under front of plenum (Vacuum source) is connected using SS braided hose to an Oil Catch Can external to the engine which Oil Catch Can is connected using SS braided hose to the dual PVC valves hard line located at the rear of the plenum. The Oil Catch Can is located on the drivers side inside wheel well (using a small channel ground and drilled to conform to the inside fender well as a spacer).

The Oil Catch Can used here is the Elite Engineering Oil Catch Can
(I use wing nuts for quick Catch Can Maintenance)

http://i287.photobucket.com/albums/l...CatchCan-2.jpghttp://i287.photobucket.com/albums/l...33b33e01af.jpg
http://i287.photobucket.com/albums/l.../OilCatch1.jpg

B. SS Air Box.
See Stainless Steel Air Box and Air Filter (L98 and LT5) For installation details including the proper K&N Air Filter.


C. Reground Camshafts and ....................2. Oil Pressure Sensor Modification.
Billet Aluminum Camshaft Retainers............The oil pressure sensor has been modified
LT5 Camshaft Specifications........................by adding a brass T fitting which can also
........................................ ........................be used to attach a mechanical oil pressure gauge.

http://i287.photobucket.com/albums/l...Camshafts3.jpghttp://i287.photobucket.com/albums/l...PresSensor.jpg

Last UPDATE of post 3 Feb, 2015

Elite Engineering Oil Catch Can Installation Details
 

Elite Engineering Oil Catch Can Installation Details.

1. General.

See for background information LT5 PCV System

The PCV hose connected under front of plenum (Vacuum source) is connected using SS braided hose to an Oil Catch Can external to the engine which Oil Catch Can is connected using SS braided hose to the dual PVC valves hard line located at the rear of the plenum. The Oil Catch Can is located on the drivers side inside wheel well (using a small channel ground and drilled to conform to the inside fender well as a spacer).

The Oil Catch Can used here is the Elite Engineering Oil Catch Can
(I use wing nuts for quick Catch Can Maintenance)

http://i287.photobucket.com/albums/l...CatchCan-2.jpghttp://i287.photobucket.com/albums/l...33b33e01af.jpg
http://i287.photobucket.com/albums/l.../OilCatch1.jpg

2. Plenum Connections.

The Oil Catch Can is attached to the Plenum PCV Vacuum port connector shown (the 12 inch SS Braided hose with hose clamp).
The fuel tank EVAP purge system goes through the electrical switch control under the plenum (shown) and out the passenger side back under the passenger side frame rail on a 91' having the Charcoal Canister on the passenger side behind the rear tire. The 90' Purge
Connection comes straight out and is connected to the Charcoal Canister located under the drivers side Headlight.

http://i287.photobucket.com/albums/l...edbdeff335.jpghttp://i287.photobucket.com/albums/l...0377d9dc42.jpg

3. Oil Catch Can Parts.

The two hose fittings are (Hose End, Swivel, 90 Degree, 6 AN Hose to Male 1/4 in. NPT, Aluminum, Nickel) and the 1/4 NPT is screwed into the Oil Catch Can 1/4 inch NPT threaded holes Swivel, 90 Degree, 6 AN Hose to Male 1/4 in. NPT

On the other ends of the SS Braided hoses install 6 AN Straight Hose Ends which fit into a 5/16 short rubber hose connected to the Front Drivers Side Plenum PCV fitting and into the PCV Dual Connector behind the Plenum (two fittings required).

http://i287.photobucket.com/albums/l...917e04b02b.jpghttp://i287.photobucket.com/albums/l...97086fc664.jpg
http://i287.photobucket.com/albums/l...0967c806e5.jpg

The hose is 6-AN Summit Racing SS Braided hose 6 AN SS Braided Hose. The Elite Engineering Oil Catch Can does not come with the fittings cited herein. Replace the fittings of the Elite Engineering Oil Catch Can with the two SS 90 deg 6 AN to Male 1/4 NPT pipe fittings cited herein.

The short SS Braided Hose section connected to the Plenum PCV vacuum is 12 inches long. The longer SS Braided Hose section connected to the PCV connector is 24 inches long. A brass 5/16 inch diameter nipple is plugged into the black PCV stock connector shown. The other end of the 5/16 inch diameter nipple is plugged into the SS 6-AN hose with hose clamp (as shown).

http://i287.photobucket.com/albums/l...4b479476c6.jpg

The two 6 AN Straight Hose Ends which fit into a 5/16 short rubber hose connected to the Front Drivers Side Plenum PCV fitting and into the PCV Dual Connector behind the Plenum (two fittings required) are not shown in the photo above.

4. Mounting of Oil Catch Can to Fender.

The Oil Catch Can is mounted on the Drivers side Fender using two Allen Head 8mm x 1.25 bolts (1-1/4 inch long) with Wing Nuts and washers on the outside of the fender well.
http://i287.photobucket.com/albums/l...33b33e01af.jpg
http://i287.photobucket.com/albums/l...anmounting.jpg

The bracket adapter (to which the Oil Catch Can Hanger is mounted) is made from a 1-1/2 x 1/2 inch channel 5-1/2 inches long with the flanges ground to fit contour of inside of fender well.

http://i287.photobucket.com/albums/l...22ed7b3764.jpghttp://i287.photobucket.com/albums/l...03ef79a9f9.jpg

5. Cruise Control and EVAP Purge System.

The Cruize Control Vacuum is taken from the passenger side of plenum. From there one vacuum line goes to the cruize control under ECM (one line) and the second line goes to the cruize control switch on steeringwheel column (second line).
The EVAP Purge system 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 fuel tank.

Cruize Control Vacuum System ...................................EVAP Purge Vacuum System with Solenoid
http://i287.photobucket.com/albums/l...5252a35535.jpghttp://i287.photobucket.com/albums/l...3761fafa4e.jpg

Last UPDATE of post 4 May, 2015

L98 Air Pump Elimination
 

The Air Induction System removed from a 90' L98

I am going with headers without the Air Induction on my 90' L98 :cheers:

Eliminate The L98 Air Pump :thumbs:

Air Pump Eliminator from Mid America Motorworks

http://i287.photobucket.com/albums/l...eliminator.jpg


Last UPDATE of post 5 Oct, 2013

Everyone who eliminated the secondaries have lost about 2-3 mpg on the highway.

:D

If you add HP as I did......well.....I was not shooting for higher gas mileage ;)

You may be correct if you just eliminate the secondaries on an otherwise unmodified LT5 engine.
Others have said there is no difference in gas mileage. Effects on Fuel Economy
You can get even better gas mileage with some modifications if you open up the engine to
better breathing, gearing and a modified Chip to match :thumbs:

Having over 500 hp is a lot of fun :steering:

My 415 car is getting better fuel economy than my stock '90 did....about 2 MPG.......both have 4.10s
:crazy:

What milage are you getting? My best when averaging 75 to 85 is 24mpg and using 6th gear much of the time.

I've been seeing right at 24 also.....it really likes 80 MPH.....gets better at 80 MPH, than 70 MPH.....my 350 car was always down around 21-22. The 350 car was putting down about 350 HP to the wheels, the 415 car oh what about 600HP
:crazy2:

I see no mention of MPG changes.
Also for long term support where would someone find
a replacement chip should something happen to the ECM and/or chip?

I had no appreciable MPG change when removing the secondaries.

After building an FBI "500" package it recently made 25.6x in cruise at 65-70 in hilly terrain, and (I was surprised) about 24.x doing some spirited driving in curvey, hilly terrain. (Jimmac was with me at the time. Ask HIM about our "road trip"!:thumbs:)

Many sources for a chip. Some tuners are better than others, tho. Marc can supply chips, Greg Vandeventer (sp? Greg?), Dominic, Pete all burn chips. Marc has a line on ECM replacement/repairs.

p.

simply "wow" :thumbs:

mpg
 

driving it home from purchase in Atlanta my chipped, samco hoses, k and n air intake but no plenum/head work that I know of ran 73 mph at 1650 rpms on I 85 Interstate and averaged 29.1 mpg doing so for 100 miles. At first I thought the dash instrument telling me that was wrong so I stopped and got gas and did the math the old way.

It's the best mpg vehicle of the three vehicles I own....by far.

Get's less when I run 5-7,000 rpm runs through the gears, obviously.