"THOR"

All datas on this page take the 99' Discovery as an example. Other models similar but not identical.

The redesigned venerable Rover V-8 goes into another battle. The new version has more power (a little) and torque (about 30 Nm) as the previous versions with the same displacement. Many people think the engine is now as far developed as it can reasonably be.

- New intake system

- New fuel feed without return line

- Intake and Ignition system Bosch Motronic

- Modified rocker cover

- Aluminium oil sump (is this a good idea?)

- Lots of new sensors for engine management

- New flywheel

Two versions are available. The first with 8,23:1 compression, 132 kW and 320Nm is for the Gulf States and Australia. The second one with 9,38:1 compression, 136 kW (182 bhp) and 340 Nm (250lb-ft) is for all the other markets.

 

The intake system

It's redesigned, with twin plenum chambers and longer intake runners to increase cylinder filling by resonating air pulse. Made of 3 parts it has rubber seals between them and must be remounted in the correct sequence (RTFM!) to get airtight and not overstressed.

The fuel injection system

The pressure regulator is in the pump inside the tank. It delivers an continuous pressure of 3,5 bars over the whole operating range. The ECM handles the different load requirements by modifying the injection timing. There's an connection for a pressure check instrument at the rear of the engine on the intake ramp near #7.

The Bosch Engine Management System

It's the type 5.2.1. The Range Rover from 1999 on uses the same system. The heads contain a NEW spark plug (or better 8). It must be replaced by the same type as the EMS relies on the varying resistance of this plug to adjust spark force and timing. The genuine is an Champion RC11 PYPB4 double-platinium spark plugs. This spark plug allows extended plug life, recommended interval is 72000 MILES! Probably a good thing if you look at the price of these little beauties. Always verify if the correct plugs are mounted. This type may NOT be cleaned as this shortens it's lifespan. You can tell them by the lug nut size: 5/8 on the new versus 13/16 on the old. (I hate this thin stuff!!!). If a wrong type was mounted you MUST also replace the High Tension Cable as the head on the plug have an other (bigger) diameter and will not fit the correct plug anymore. This is not visible and you don't feel it either but I trust LR on this. My personal oppinion on changing spark plugs as expensive as these: Leave it to the dealer. If you break ONE it will cost you more than the quarter hours work they charge for this.

The Bosch Motronic is is similar to the systems used on BMW series 7/8 on their V-8 and V-12's. However an unit from such a car can not be substituted if yours goes goodbye, they have a different command set in their EPROM.

It does a lot of fine things and is best not touched without the TestBook, the correct Manuals and a great deal of precaution as it's extremely expensive!

The ECM is mounted on the A-pillar to the right. It has 5 color-coded electric connectors. Don't touch them. They are sensible, thin and must be demounted and remounted in an special sequence. The ECM holds its data in an flash EPROM that can be programmed with the TestBook.

The ECM stocks the faillure codes, called code "P". This code LR had to give to the makers of diagnostic tools. The "P's" are defined by the laws on the OBDII. An code stays in memory for 40 "trips". (More on this in the TestBook chapter) On NAS specs, the ECM will light an indicator -the MIL-light- to show an irregularity if the same fault happens on 2 consecutive "trips". Only exception to this is if missfire occurs and the cat can be damaged. In this case the light goes on immediately. On non-NAS specs, the codes are only stocked in memory, the light is not activated.

The ECM starts the engine after input by the key.

The TPS- Throttle position sensor on the intake has no way to compensate manually or to set up.

 

New distributor chain cover

This was made to include the oil filter adapter. It uses an Poly-V belt, as on the 4,0 NAS and 4,6's. It's tension is regulated by an automatic tensioner. They are color coded in 4 different lenghts. The Alternator has been uprated to 130 Amps. The PAS pump has higher capacities but looks still the same. The A/C compressor was replaced by the type already used on Range Rovers.

The Flywheel

It has been modified to accept bores of 6° distance, the size of one hole is 3°. 2 holes are missing at 60° before TDC of cylinder 1- so there's 58 holes left. A small ring has been machined in the flywheel, allowing the head of the sensor to fit inside the holes for best signal.

 

Here an example of an 480° rotation and its resulting signal:

 

The signal from this sensor is critical to the engine working. Without this signal the engine will not start or when the signal fails on the run it will stop. In this case the MIL light will go on and the tachometer will immediately go to 0. When shutting down in a normal way the ECM stocks the exact position of the cylinders to start later in the most effective way.

The camshaft sensor

 

It's located in the front cover immediately near the front end of the cam. It's an Hall effect sensor and the cam sprocket has 4 different teeth who give different rectangular signals to the ECM (see picture) so this exactly knows in which position and cycle every piston is. Here lies the difference in cams to the previous version used. The old differ from the new in the position of those teeth and an error code will be stocked in the ECM if you use the wrong cam.

The temperature sender

This is a vital part in the ECM management as a lot of functions rely on the warm/cold indication. If the sender fails, the ECM will compile instead signals as running time of the engine and temperature of the intake air to compile an approximative temp condition. The sender is the same as on the 1999 Range, but here only 2 of the 4 electrical connections are used.

Knock sensors

One on each side of the block. Piezo-electric. Sense each cylinder and allows the ECM to adjust the spark timing to the most effective position just before knock occurs The engine is supposed to run on 95IOR Unleaded Super but can also be run with 91 IOR Unleaded Normal fuel. A slight knocking may be felt during a short time when switching as the ECM "learns" about the new quality and adapts his settings. This can however NOT damage the engine.

Oxygen sensor

Vital for monitoring gas mix in the exhaust and adapting mix in the engine. The new Disco uses 4 for NAS spec cars and 2 for CEE spec cars. (NAS uses 2 sensors behind the cat to monitor its function). No sensor is mounted for other market specs.

Ignition

2 double coils are used. Cylinders 1&6, 7&4, 5&8 and 3&2 use the same coil. The "lost spark" system is used to get a precise and intense spark.

Injectors

Common rail technologie, ECM opens each injector individually. 3,5 bars pression, test connection at the back to injector #7. Take great care in connecting to this. Each injector uses 2 seal rings which MUST be replaced every time it is taken out. Oil them slightly with engine oil before remounting. NO grease or copper grease nor any sealant (they must have a good ground). An good injector must have an resistance of 14,5 Ohms at 20°C with a tolerance of 0,7 Ohms. If they do not meet this, they are most likely shot.

CO-adjustement

This can only be made on non-catalytic cars. But you will need the TestBook for this- bad luck.

TestBook diagnostics

The ECM stores the following errors for each occurence:

The number of occurences

If the fault is at that moment still present

If not, how many "runs" have been made since last occurence

The operating time the fault happened (from hour0 being the first time the ECU was set under tension, no relation with actual time)