Changing Spark Plugs in the 3rd Gen V-8

When you open the hood this is what you first encounter. The big Valve cover you are looking at is really just an appearance cover to keep dirt ans water out of the spark plug wells. It is very effective.

The manual recommends spark plug changess for the 3.4L V-8 at 60K miles in hard usage. Generally speaking I think I fall into that catagory easily, what with the hard driving, and autocrossing, and track time I put on my car. So, one weekend I figured I would attempt to change out the spark plugs on my 1997 SHO. So before I picked up a tool, I read the instructions.. Severals time in the Helms manual.

First, a primer on SPARK PLUGS:

For what its worth, the 3.4L SHO engine uses a MOTORCRAFT AWSF-32FM plug. When you go to your FORD dealer, they will not have it in stock ( I called 4 dealers), and in fact will have never even heard of that plug. When you go to your local parts house, they probably wont sell MOTORCRAFT plugs. So, Before you get ready to change plugs, order them from the dealer, and have them in hand before you ever pick up a wrench. Another Option is to go to http://www.carparts.com. They offer the MOTORCRAFT plugs at a significant discount. About 2.41 each.

There are several other makes of plug that are listed as interchanging, however, Use these at your own risk. The Bosch Platinum, and Platinum +4 plugs have a differently shaped ceramic insulator on top. The shoulder next to the tip is very narrow and not as wide as the MOTORCRAFT part. This is significant. The 3.4L engine uses Coil on Plug ignition. Whet this means is that each plug has its own coil and while the fit is not loose, it does not snap onto the plug like wires in a conventional (Old Tech) ignition system. The inside of the boot (bottom of the coil) has a spring inside it, and when the coil is bolted down onto the plug..Yes, I DID say bolted on.... the connection is made on the shoulder. So while a narrower shoulder plug may work, in my personal opinion, I wouldn't want to chance a bad connection.

In spite of the poor quality of the picture, you can discern what you need to see. Displayed here are a BOSCH Platinum (left) and the OEM MOTORCRAFT Plug (right). Note the difference in the thread lengths, and the obviously wider shoulder on top of the MOTORCRAFT plug.

As for the rest of the plug, I compared this to a Bosch Platinum, the upper insulator is approximate in length, and the length from the spark tip to the seat of the plug is close. The MOTORCRAFT part has maybe ½ inch of threads. The Bosch has threads the full length of the lower part, almost an inch worth. Again the seating surface is the same, so this means that almost half of the threads would be exposed. Important? Probably not. But Ill order my OEM plugs anyway. They list for 6.30 apiece and the alternates go for anywhere from .99 to 2.50 each.

This is what the front of the 3.4L SHO motor looks like when the Appearance cover is removed. Note the easy access to the plug Coils. Oh, how nice it would be if the rear bank of plugs was this easy to reach!

Front Plugs Only:
1) Disconnect battery ground cable.
2) Remove two flange bolts and four cap nuts retaining appearance cover to engine.
3) Temporarily remove oil filler cap assembly and remove appearance cover. Reinstall oil filler cap assembly.
4) Disconnect the engine control sensor wiring from the intake manifold runner control (IMRC) deactivation motor.
5) Remove three retaining bolts for the IMRC deactivation motor from the LH cylinder head cover and position the IMRC deactivation motor out of the way.
6) Disconnect engine control sensor wiring connector from coil per plug units.
7) Remove coil per plug unit retaining bolts and remove coil per plug units.

This shows the where the Tank stays (A), the Transducer Brackets (B), Power Steering hose bracket (C), EGR Valve Mounting (D), and the Tank Vacuum (E) fitting are located on the back of the Surge Tank.



Step 7 and 8 are where the next hour will be spent. The transducer bracket is on the back of the Surge Tank. THIS is why you pulled the Vent cowling. Two bolts, 8mm, will drop back a little.
When disconnecting the two rear intake manifold supports or braces or stays (pick a term) you have to reach over and under the surge tank to reach them. The top right side is easy. The bottom right side has a nut (12mm I think) that attaches a grounding strap.

After pulling the Surge Tank off this is what you see. (A)Fuel Pressure Regulator (B)The PCM Computer, alot of room to work with now! (C)This is the sensor bracket. (D)The EGR tube to the exhaust, Don't forget to hook this back up. (E) The top of the rear bank of spark plugs, The SURGE TANK sits on top of them and acts like the appearance cover, deflecting most water, dirt and crud from landing on top of the coils.

Pull the surge tank out set it aside. You may want to paint it, clean it, de-gunk it while its out.

also, put a towel over the eight little intake tubes while you work here, so that you don't drop any nasty things in on top of the valves..

Installation of the Tank is easy, and took me about 45 minutes to accomplish.

With changing out the 8 spark plugs, and what I now know, this job which took about 4.5 hours will only be 3 hours tops, next time around.

On a 1-5 wrench scale. This is definitely 4.5 to 5 wrencher.

This job is not technically difficult, but it is confusing, and a lot of bolts come of, and vacuum lines and hoses. If you are not confident with this sort of thing I recommend that you pay a dealer to do it. Let HIM get all scratched up. I am guessing that at 3 hours labor at 65$ plus 54$ of parts, plus miscellaneous things this is a 250$ job at a dealer.

What's YOUR time worth?