Whisper Lid

1 Whisper lid
  1. Flat head screwdriver
  2. Intake air temperature sensor*
  3. Rubber grommet**
*Not needed but highly recommended *Intake Air Temperature Sensor Part     Number 12160244
**Rubber Grommet Part Number 24504388
Expect approximately 10 – 40 minute install time (depends on how easy your mass air flow housing and rubber grommet/sensor come out)
Tools and materials you will need:
Circa July 1999
Car: 1999 Z28 Camaro, 5,200 miles
Eric and Kelly Barger
Email: help@installuniversity.com

People who helped us from major tech talk to general advice:
Elmer Boggs (
  • Jack (Jack98SS)
  • All my buds at LS1.com

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    Perform all these installs at your own risk.  Know how to use all of your shop equipment and take necessary safety precautions when performing ANY modifications and or maintenance items to your vehicle.  Seek the advice of a paid professional and do not substitute this publication for the advice of a paid professional.  This product is how we accomplished our installs and is not meant to be carved in stone.  We are not responsible for a mistake, misprint, or any other error found in this guide.  This guide is intended as a supplement and not to be your only source of information.
    Purpose:  This modification will replace the factory air box lid/silencers and the mass-air-flow housing (MAFH).  This will smooth out and increase airflow through the air box lid and MAFH giving your car some extra horsepower.
    Reminder:  Make sure you have the keys out of the ignition.  Why?  When you remove the sensors from the air box lid assembly you do not want to start the car.  You will set the Service Engine Soon (SES) light.  If you do start the car without placing the sensors back in you can easily reset the SES light by following these steps:
        1.  Turn key to the "on" position but don't start car     2.  Pull the PCM BAT and PCM IGN fuses in engine compartment     3.  Wait approximately 5 minutes     4.  Turn ignition off     5.  Replace fuses     6.  Start the car and then make sure the light has gone off
    1.  Open the hood of your car and look in the front and center of the engine compartment.  Locate the air box lid metal clamps (see blue arrows in Figure 1)
    Figure 1
    2.  Go ahead and undo the air box metal clamps (see blue arrows in Figure 2).
    Figure 2
    3.  Now you will have to remove the two plastic clips that hold down the air silencers (see blue arrows in Figure 3).  Refer to Figure 4 for the three-step process to remove a pushpin.  A.  Locate the pushpin on the driver's side of the air box assembly.  B.  Place a flat-head screwdriver underneath the head of the pin while holding down the "collar" portion with your thumb.  C.  Pull pin up and remove.
    Make sure to keep the clips just in case you need to replace your factory air box lid for a trip to the dealer or other need.  If you do break the clips they come in packs of ten (10) and are really cheap.  The GM part number is 12551599.
    Figure 3
    Figure 4
    4.  Locate the intake air temperature (IAT) and mass-air-flow (MAF) sensors (see blue arrows in Figure 5).
    Figure 5
    5.  Remove the two sensors from the air box assembly shown in Figure 5.  You can see an example showing how to remove the sensor connectors safely in Figure 6.  Gently pull the tab out and lift the sensor out of the housing.  
    Figure 6
    6.  Go ahead and locate the rubber flexible hose that runs from the MAFH to the throttle body (TB) (see blue arrow in Figure 7).  Take a flat-head screwdriver and loosen the metal clamp.
    Figure 7
    7.   Grab hold of the air box, lift and pull towards you (see Figure 8).
    Figure 8
    8.  Before you get excited, be very careful with the MAF sensor.  Don't touch ANY of the little thin wires (see blue arrows in Figure 9).  You will screw it up and cost you major bucks ($$$) to get a new one.
    Figure 9
    9.  Take a flat-head screwdriver and loosen the metal band clamp that fits over the air box lid neck that connects to the MAFH (see blue arrow in Figure 10).
    Figure 10
    10.  You need to pull the MAFH out of the neck on the air box lid (see Figure 11).  This might be a very hard step to complete.  The MAFH is very stubborn to come out.  We heated the neck of the air box lid using a hair dryer and the MAFH finally came out.  DO NOT PUSH on the MAF screen from the inside of the air box lid!  That will damage the screen and that is the last thing you want to happen.
    Figure 11
    11.  This step will also be a hard step.  You will need to remove the IAT sensor and rubber grommet from the factory air box lid (See Figure 12).  We suggest buying another IAT sensor and rubber grommet from your local GM dealership.  The part numbers are listed at the top of this install in the Tools and Materials.  This step was much harder for us than removing the MAFH.  However, if you want to use the factory pieces then you will need to pull the IAT sensor out and remove the rubber grommet.  We used a pair of needle-nose pliers.  Be careful not to tear the rubber grommet!
    Figure 12
    12.  You will need to place the rubber grommet and the IAT sensor in the whisper lid (see blue arrows in Figure 13).  This will be easier than taking them out.  You just have to move them around a bit until they slide in.  The IAT sensor will be difficult to slide in so be ready to spend some time on it.  Be sure you turn the IAT sensor so the part number is facing upward.  This will ensure the sensor connector will be turned the correct way so you can get to the release tab in the future. 
    Figure 13
    13.  Take the metal band off the air box lid neck that you loosened up (if the Whisper lid did not come with a metal band clamp) in Step 9 and place it on the Whisper Lid's neck.  Slide the MAFH back into the whisper lid and tighten the metal band clamp using a flat-head screwdriver (see Figure 14).
    Figure 14
    14.  Grab hold of the whisper lid (in the same manner you grabbed the air box lid in Step 7) and push the rubber boot back on the throttle body.  Make sure you get the rubber boot all the way back on the throttle body.  Then tighten the metal band clamp on the rubber boot (see blue arrow in Figure 15).
    Figure 15
    15.  Reconnect the wires to the IAT and MAF sensors.  If you do not you will get the Service Engine Soon (SES) light on your dashboard.  No big deal but it is nice to avoid the hassle if you can.  If you do set the light you can reset your PCM by using the steps mentioned in the Reminder.
    Figure 16
    16.  Place the tabs of the air box into the small holes (see blue arrows in Figure 17).  Push back on the box to get the tabs in the holes good and snug.  Lower the lid and put the clamps back on the air box.  You might have a little problem getting your metal air box clamps to stay shut.  Just make sure you push the lid far enough back.  If you have problems with the metal clamps staying shut, be sure to get the upper lip of the whisper lid behind the lower lip on the lower air box assembly.  The lid will get easier to take on and off once it has been installed on the car for several weeks.
    Figure 17
    Comments:  Look at our finished install (See Figure 18).  The lid really cleans the engine compartment up and gives you some extra horsepower to go along with the looks.  At the time we completed this mod we had no other performance modifications.  We could tell a noticeable difference in throttle response and additional horsepower.  We experienced a slight "whistling" type sound from time to time.  Don't worry about that sound if you experience it.  The sound occurs because we removed the silencers on the air box lid assembly.
    Figure 18