I just finished a tune up on my gasser this weekend. Being the third time I have done it since I have owned it made it go a little quicker. The job is some what a pain in the arise, I hope you have small hands and allot of patience. The Hummer does not offer a lot of room to get to things, you will have to remove several things to get to the plugs. Let me list off some things to look for..

First go to you local parts store, ask for AC Delco plugs (Plats and off brands provide no more power and wear out faster), wires and a cap and rotor off a 1995 Chevy Suburban 2500, 4WD, with a 5.7L Chevy 350 engine. (Same motor that the Hummer used in 95' and '96. By The way, I'm assuming you have a 1995.

Tools: You might want to pick up some new tools at the parts store that will make your life easier. Buy a 1/2 and a 9/16 box end ratchet style wrenches. This will make removing the passengers side heat shield easier and also the 9/16 will make rear brake jobs easier. I say 9/16 or 1/2 cannot remember what size the bolts were, just to be on the safe side. (They look like a normal open end wrench but they have a ratchet mechanism built into the end.) If you do not have a 5/16 socket or open end buy one. (There is a bold on the heat shield that requires it.) A breaker bar, you will have to remove 2 exhaust manifold bolts that hold a bracket that holds the heat shield in place. Depends how strung you are with a 1/2 in ratchet, I needed the extra torque for mine, they were welded on with mud. Also buy a 1/2 to 1/4 socket reducer this will make removing the spark plugs on the drivers side easier. A normal 1/4 socket with and extension is to long, but the 1/2 with the reducer and the socket fits like a glove.

Ok now that you have spent half the day in the parts store, you are ready to get dirty.

Remember put the emergency brake on and "please" chock one or two wheels. While removing the dog house the Hummer may gear out of gear. Get a piece of split fire wood of something the Hummer will not roll over. (Not including yourself).

Now for the fun part...

Grab a Phillips head screwdriver preferably a #8.

Glove Box removal:

• From the passengers seat.
• Open the Glove box and remove the screws holding it in place.
• Remove the Glove Box.

Dash Pad Removal prepration:

• Next look near the door jam where you dash pad meets you should see (3) three Phillips head screws remove them. They should be chrome with a pretty chrome washer sitting behind them.
• Then take a Slotted/Flat Blade or Phillips head screwdriver, look at the front bottom of your dog house there should be one shiny chrome or black screw holing it in place on either side, remove them both.
• Next jump over to your driver's side seat with Phillips in hand. Look at the driver's side window sill where the dash pad meets there should be (2) Phillips head screws remove them.

Temp/Oil and Volt/Fuel gauge removal:

• Now you are going to remove your oil/temp and volt/fuel gauges they should be held in place by 4 Phillips head screws each.
• After removing the screws, carefully remove the gauge's let them hang in place. (DO NOT remove connectors) NOTE: We removed the gauges to access a "L" type fastener bolt, from the factory it should be glued in place, but due to dealer/past owner age the bolt will come free.
• Now after locating each "L" bolt hold the one closest to the drivers side with one hand while you unscrew the plastic screw located on top of the dash pad. Repeat this process for the other plastic retainer. Make sure the "L" clip does not fall down into the dash. NOTE: If the "L" bolt falls into the dash start cursing, after you have calmed down try to locate it by moving the wiring harnesses around.

Dash pad Removal:

• Now remove the dash pad, place it in a safe spot.

Dog House removal:

• Now is time to remove the dog house, let the fun begin.
• There are several connections to take note before pulling out the dog house:
  • The ECM connections (BIG shiny gray box with 2 big connectors)
  • The DSRA (Digital Speed Ratio Adapter) Little white box left of BIG shiny box)
  • Your heater/AC control module
  • The 2 connectors leading to you key less entry
  • Your cigarette lighter plug
  • The light going to the ash tray
  • The connection to your Tach
• Pull you dog house slightly forward exposing the connectors, remove all above mentioned connections except the ECM and the DSRA. You can unbolt the ECM by loosening (4)four 5/16 bolts and the DSRA is velcroded in place.
• Carefully pull the dog house backwards angling the top front downwards while removing it. It should take some thought but it should come free.
• Whew, that was a lot of work but I still don't see the engine...don't worry, with everything out of the way the engine access cover will come out.

Engine access cover removal:

• To remove the engine access cover, unfasten the rear and front fasteners, the two in the rear work like the latches found on older jeeps (CJ, YJ). The front work like normal latches you would find on a tool box. There are two, one each side one in the front and one in the back. Now that we have made sure the access cover is unfastened, grab the back of the cover where you found the jeep type fasteners. Pull it towards you pulling the back upwards and forcing the front downwards. Work it towards the driver's side. Be careful not to bend or damage the solenoid.
• I have not found the best way to remove this cover, someone on the list might have a better idea, but I know this process works for me.
• Congratulations you see a pretty 5.7 engine staring at you.

---Actual start of tune up----

Passengers side heat shield removal:

Now grab the a 9/16 socket and jump into the passengers seat.

• Look at where the Tranny dip stick is fastened to the engine, remove that bolt to free the dip stick. Be careful you just want the tube free so you can move it slightly left or right to access things, do not attempt to remove it.
• Now grab the box style ratchets I told you to buy. You should see a heat shield on the passenger's side. This will be held in by (2) bolts 1/2 in or 9/16 cannot remember. Remove these bolts the rear can be accessed by the passenger's seat the front is access by the engine bay.
• Now follow the heat shield towards the read around where the Tranny dip stick tube is. You should see a 5/16 bolt holding the front shield to the rear shield, remove this bolt.
• With the heat shield loose slide it forward until the rear of the shield clears the tranny tube, then pull it backwards towards you and out of the engine bay.

Heat shield support bracket removal:

• With the heat shield out of the way, you can debate removing the rear heat shield support bracket. I had to remove it to get to my rear plugs and wires, try replacing the two passenger rear. If you cannot access them, then remove the bracket. If you have to pull the bracket the breaker bar will help since the space is tight and you will need some leverage.
• With plug removal and installation, the passenger's side works fine with a 1/4 ratchet a small extension and the socket.
• The driver's side is a different story. The front (2) you will have room to work, but for the (2) rear I have success with a 1/2 drive with a 1/4 reduce with the socket being it, gave me just the clearance I needed.
• I do not know what brand of tools you are using but I base all my measurements on my SK drivers and extensions.

Now with the plugs done, it is a normal jobs for the wires cap and rotor.

You can fire the beast up as long as you have the DSRA and the ECM connected. A good thing to check for before you reverse these steps and put every thing back together.

Hope this helps, I would say it is not the most enjoyable thing to do, but it has to be done.

Matthew