Plenum Removal, Spark Plug Replacement

First off we will start by removing the rear Turbo outlet tube. Disconnect the hose assembly remove the support bolt
on the plenum and then the bolt on the flange on the turbo at the opposite end as shown below. Cover the turbo
hole immediately with either tape or something round that will fit into the opening without falling out or falling in.
This is very important and a step not to forget or eliminate. Drop something into the hole and you have big problems.
It will result in having to remove the rear turbo to get out whatever you accidentally dropped in. Not noticing you dropped
something in and restart the engine after finishing and you have a trashed turbo. Not worth eliminating the time spent
making sure the opening is covered and secure, so I say again, cover the hole before going any further.

Now moving to the front in the photo on the left, below, remove all the plenum bolts using a #12 metric socket. There are
5 bolts and two nuts, one on each side. Also remove the injector wiring shield bolts. Now moving to the photo on the
right, remove the two bolts on the flange for the EGR Temperature Sensor Tube. and the bolt for the supporting bracket.
Bolt locations are shown by the arrows in both photos

I can't stress this enough so I am including another photo of the turbo outlet plugged for protection. We are moving
over to that general area and the risk is increasing.

Remove the fuel cable bracket bolts (as you can see the turbo opening is right below this area)
I changed the plug I was using for the turbo outlet to one that was more secure than the one I was using in the
photo above.
Remove the vacuum tubes shown by the arrows. If you do not have your boost controller hooked
into the tube coming off the back of the plenum, you do not have to remove that line.
I had to because the "T" installed in the line ( right photo circled ) went to the rear firewall and was secured
and would not allow swinging the plenum off to the side so both ends had to be disconnected.
In the right side photo you will see a arrow pointing into the darkness at the upper center of the photo.
There is another bolt that is on a supporting bracket right in back of the throttle body that has to be removed back
in there. I couldn't get my camera in there to take a photo, but it is there, you'll find it. (Attack from the passenger fender)

In the below photos you will see my Y pipe has been removed. This would be the next step. In the left photo is a closer
view of the wire connector bracket. Though you do not have to remove the bracket, there are only two screws so I
chose to remove them to eliminate any stress to the wiring when the plenum gets flipped to the side. The right photo shows
the "Y" pipe removed. The plenum should now be ready to flip over to the passengers side.

  On the left you will see the Plenum flipped to the side. I used a boot shoe lace to hold it up there and it is tied off
to a hole in the hood frame and the vacuum stud on the end of the plenum. I have it flipped up enough to easily work
on the area below rather than providing undo stress on the hoses by flipping it further than necessary.
On the right is a piece of cardboard that I have written the bolt locations where the bolts laying in the circle are from.
It helps in reassembly. You can use your own procedure for it but I just thought I would throw that in for an idea.
You will also notice U shaped clips on the cardboard. They are from the injector plugs and will be covered in the
injector section. Spark plug change out is fairly self explanatory, but I will provide a couple photos on it.
This cover Plenum Removal. Of course reassembly is just the reverse. I replaced the plenum gasket
only because it is inexpensive and why bother with the chance of a leak. Part number for the plenum gasket is
MD143791
I assumed it had not been replaced at 60k when they did the tune last time.

Spark Plug Replacement
 

Unscrew old plugs , install new,, that's it!! haha

Ok, here is a little info I found out about mine that I will pass on but other than just changing out the plugs
there are no special instructions.

The plug needed is part number
MS 851336 and Plug Number PFR6J in the NGK version.
The NGK Plug is the preferred plug of choice. It is designed to last through the 60k miles
Others have been tried, like Bosch Platinum and Double Platinum, but they have not had good results.

My plugs showed signs of typical results after 60k miles. Original gap is supposed to be .040 however
mine had opened up to .045 on 4 plugs and .048 on two plugs. This will cause what many might think of
as fuel cutout at higher RPM's What happens is increased boost actually blows out the spark and the cylinder
misfires. After test driving when I was done the engine ran smooth all the way through the RPM spectrum.
I have to add that when I installed my plugs I regapped them to .032 because I also have increased boost and
installed larger injectors.

Here is the difference between .040 stock and .048 as shown between the two plugs. Tip wear can be seen
on the old plug but still looks pretty good for as many miles as it has seen.

Here is my set of old plugs. You can tell a lot from plugs. The light tan dry color you see on the tips
is the sign of a healthy engine. Dark tips with an oily residue is a sign of ring wear and you
will probably see this if you are burning oil due to rings or bad valve guide seals.

That's all folks!!

If you are changing out Injectors, click here
 
 

For Comments or questions on this Page
Click Here
 

 To Return to 3SI Tips and Tricks Click the Image below

Photos and text Copyright John C. Adams of
adams@icx.net
Copying to any other location is prohibited
Photos contain copyright stamping
For questions send e-mail Last update 08/02/00