Satan himself designed that engine bay layout

AKA Discovery Spark Plugs and Wires Replacement

If you've been following I've been slowly doing a tune up on the now not so beloved 2003 Discovery. I say that due to the fact that the plugs and wires on this vehicle were not designed in a friendly sort of way. Matter of fact I am convinced Satan the Dark Lord, himself, designed the layout. If I didn't know better I would have said it was a Chevrolet when I figured out what it would take to do this job. I'll let my displeasure of this design go with just this last statement, "I hope whoever signed off on the final design on this vehicles engine bay gets the rickets and a nasty case of herpes simplex 10."
Thanks for listening to me vent I feel much better.

Let begin by getting a survey of the engine bay. As you can tell in this picture its pretty tight in there. Compared to my Range Rover Classic's engine bay it's ridiculusly cramped. Basically the intake has to come off if you have any hope what-so-ever of getting the wires swapped. The plugs are mostly covered up by a polution reduction system that blows heated air into the exhaut manifold via an air pump. This pump runs about for about a minute when you start up. Then it shuts off and only comes on at the corner of Tecumseh and Flood just a couple of minutes after I exit the freeway on the way home. I don't know why...it just does.

So you have to take all those bits off the top of the motor. I started with the air intake. I had to fix the snap down due to the plastic failing last winter. I used a couple of zip ties to hold it down. Mark that as use number 346 for zip ties.

The throttle cables must come off. Here is a close up of the ends. Then you remove the rest of the intake, including the mass air flow sensor. There is an odd device on the under side that apparently is cooled by coolant piped all the way over from the passenger side. Mine is apparently leaking At first I couldn't imagine what had gotten up there and melted. Crayons came immediately to mind. I haven't ever smelled any coolant so I figured it can't be that bad.

There are hoses that run from the seconday air pump to each side of the engine. The pipes that cross behind the engine are as you could probably guess right above the plug wires. Each manifold has a set of pipes that come up to a vacuum controled valve for lack of a better term. Could I have looked all these part names up? Yeah probably. This is an image of the pipe. They are very flexible and getting them off without tearing them was a challenge. You can see the two wrenches, 18mm and Cresent (spanner) used. You have to come up from underneath the manifold to get it on the backside. The hoses that cross behind the engine and the firewall are held in place by a bracket. It is not easy to get to.

The hose bracket is held down by half of the bolts used to hold the coil bracket down. Again this is a ridiculus place. During reassembly I dropped the extention and my only 8mm socket down behind the engine. I had just tightened down the bolts and had no way to get it out. I wound up going back to the hardware store, buying a set of deep well sockets and another extension. I also stopped by Harbor Freight and got a couple of remote grab items. The magnetic one worked great.

I finally got the intake off. It was hard to reach and difficult to lift out due to the location back in the bay. I injured my back by the end of the day and spent most of the next day on muscle relaxers. Here is the top of the motor sans intake. I have labeled a few things in this picture. More on the bracket later.

Now you get the coil packs out. Here you see a better picture of the bracket the air hose bracket connects to.

Now I swapped the plugs and put the wires on. The coil packs out and on top made this pretty easy. You can see I stuffed shop towels into the intake to prevent me from dropping sockets and other foreign material down in there.

This is a good example why you always swap wires AND plugs together. Every time before that I just swapped plugs I inevitably damage one of the spark plug wires getting it off. You can use some type of silicone on the insides but it always cooks out so I stopped bothering with that step.

This is the position you have to be in to work with the brackets at the back of the engine. You can see the glint of my grandpa glasses in this last picture. I had to have them on to see the bolts and other items. I've never had to wear my glasses before this job and I guess I'll be wearing them on most of the jobs in the future as my eyes are getting worse each year. You can also see the rag rugs I used to cushion the sharp bits from my ribs. It only partially worked as I still have bruised ribs from laying up there on the first day.

I said I'd come back to the bracket I labeled above. After I got it all assembled again. I started up the Rover and immediately the Service Engine light came on. I grabbed my code reader and got the following codes. I immediately got on the Land Rover Only forum and got the following detailed list from ArmyRover. (thanks a lot buddy)
p1884 - Engine Coolant Level Lamp Circuit Short to Ground
p1451 - Evap Emission Control Sys Vent Control Valve Circuit
p0414 - Secondary Air Injection System Switching Valve A Circuit Shorted
p1482 - SCP
p0445 - Evaporative Emission Control System Leak Detected (gross leak)
p0448 - Evaporative Emission Control System Vent Control Circuit Shorted
p0102 - Mass or Volume Air Flow Circuit Low Input
p1590 - unk
p0340 - Camshaft Position Sensor Circuit Malfunction
p0134 - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
p0154 - O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)

And before you ask for it...here's the link to the site for the codes.

Disco Mike's reply was bang on. I had not messed with any of that stuff so what happened? Well long story short I had shorted out one of the wires in that loom between the bracket and the intake on reassembly. That was a big relief I can tell you. As I was worried I would be taking it in to a shop to sort out that big a list.

It must be noted, I swapped the plugs and wires on my Range Rover Classic in less than an hour the same night I found the wire shorted.

This job, not counting my bracket SNAFU was about eight hours. In hindsight the job while not technically difficult, was a 10 on the Pain In The ARSE meter and the meter only measures up to 8. I'm not sure what a shop would charge for this but whatever that was...is probably a wash if you have the time to do it yourself. On the Difficulty Scale it rates as a 4. Mainly because it was very difficult to get all the bits off and required a crap load of tools and reading the procedure on the Rave CD.

Thanks for reading and happy Rovering.