Changing P38 Engine ECU

Hi Chaps

I have a 1997 P38 4.6 Range Rover and it runs just fine really but the other day I was offered another engine ECU from a scrap vehicle that had been chipped.

The ECU has a sticker on the side from a recognised Land Rover specialist (Although I can't for the life of me remember who it was!) and something about Happy Hedghog ECU Chips and it states the rev limit at 5750rpm.

I'll try to get more information about it but I'm tempted to try it anyway as he is offering it for free and it's from the same year, same size and same type of engine so should be good.

Question is, Can you simply swap engine ECU's over or are they tied into the BECM and security system in some way?

I know I could just try it but don't want to upset the BECM in any way and be left stranded with a non functioning Range Rover!

Cheers

Craig.

It will be a Gems ecu and may be interchangeable without resetting the security code. Are you 100% sure it's from a 4.6 as the original mapping is different on the 4.0.
Worst case scenario is that you MAY have to resynch the Gems to the Becm so check around for someone who can do this for you if needs be.
Best bet is to find someone with the diagnostics, swap the ECU's over whilst they are there just in case.

I think the GEMS ecu may have to be put into learn mode via diagnostics before it will work.

Theoretically, the GEMS will recognise any code between 0 and 65535.
The majority of Gems codes are 65535 so there is a chance it may be a straight swap if both are set at 65535. However I have come across ecu's with 0.
Hence my suggestion that having someone standing by with the diagnostic system to do a relearn, if required, when they are swapped over.

Irishrover said:

Theoretically, the GEMS will recognise any code between 0 and 65535.
The majority of Gems codes are 65535 so there is a chance it may be a straight swap if both are set at 65535. However I have come across ecu's with 0.
Hence my suggestion that having someone standing by with the diagnostic system to do a relearn, if required, when they are swapped over.

Click to expand...

Makes good sense.I wonder if there is any other method of ID as well.If you have a BBS single vehicle msv ,will it now be recognized by the system or will you have to pay BBS for a new tup code to recognize the replaced gems ecu?

Cheers guys

Didn't think it would be as easy as unplugging it and swapping over!
I have a useful, Friendly Land Rover dealer nearby so will take it there and swap over in their carpark, just in case......

Actually they might be able to take a look at my BECM as well and see if there is a reason the left front central locking doesn't work either.

Cheers

Craig.

Just to answer a few questions,

Yes, I'm pretty confident it's a 4.6 ECU, I saw the vehicle it came out of and a friend has bought the engine too which has 4.6 cast in the crank.

It is a Gems type EFI System.

I'm going to pop over there tonight and grab the ECU so I'll check what the sticker says on the side of it and post back.

Cheers

Craig.

Got the ECU, Al the codes match and the sticker on it says it is a "Tornado" modification and was done by James French 4x4. Looks exactly the same as the one sold by RPI.

I'll let you know if I swap it over and notice a difference!

Craig.

The Tornado chip is a simple 2 chip plug in. If you can't simply swap the ECUs, then open both (watch out for a squirt of security fluid from one of the case screws if yours hasn't been opened previously!) and swap the chips over. The 2 Tornado chips are both a piggyback arrangement, you'll see when you open the ECUs. Easy to swap the chips, but be careful of bending the pins. Currently the Tornado Chips cost £780!!! Fitting instructions here: RPi Engineering - V8 Engine - Carburetion and fuel Injection

Cheers Alan

I've just did exactly as you suggested. Opened both ECU's next to each other on the bench and everything looked identical apart from 2 chips with Tornado stickers on the top so carefully removed the Lucus plastic covers on my one and prised out the original chip.
Carefully removed the chips on the replacement ECU and simply swapped them over.

Screwed it back together and popped it back in the vehicle and it started and ran straight away. Job well done and I have a spare ECU now!

It does feel different in some way. A bit more throttle travel seems to be required to get it moving but the power seems smoother and more progressive. Maybe I'm imagining it but certainly something has changed.
Does anyone know if the gearbox changes are linked to the ECU as well as the changes seem slightly different now too?

£780, Jeez, Someone is making a profit! Those chips cost the best part or £5 from RS then all you need to do is program it!

Thanks all for the help

Craig.

Hi Craig,
It's not that easy to copy them, the EPROM is easy enough to copy, but that's why they are plugged into an encoder chip! This prevents the EPROM from being copied as they are useless without the encoder chips, Mark Adams spent a long time and a lot of money designing these maps and isn't prepared for someone to rip them off. All the chips do is alter the fuel injection and ignition maps, giving the engine a little more power and torque, there's no program change to the gearbox etc. However, as the engine is producing more power and torque the gearbox will react slightly differently than with the standard chips I guess. These chips are a lot better for the engine too, and used gently supposedly can increase MPG. The fuel map is slightly richer in the mid throttle cruise area where previously the LR chips are programmed to really lean the engine out, making it run hot as a consequence and some argue it's this lean hot burn that contributes to cylinder liner slip. So not only do you now have a bit more power, you possibly are being kinder to your engine now

They actually retail at £695 Range Rover P38 V8 Sagem Gems ECU Tornado Chip Chips | eBay UK
but is this too expensive? RPI sell them, and a lot of research went into their development, but is £695 worth the 15 to 20 HP power gain and the possible extra longevity of your engine, which hasn't been proved? My last P38 had the GEMS injection engine and I suffered a slipped liner so had to install a new engine. I now have a later Thor engined P38, prior to my purchase it suffered a slipped liner even though the Thor map is different. It now has a new lipped linered engine, these liners can't go anywhere. Hopefully.

Your right Alan, I guess you are paying for the development costs rather the costs of the goods.

I'll let you know how it goes as it says the ECU "Learns" the engine over a few weeks so it may get even better yet once it realises I have a couple of other modifications fitted.

I must be lucky as the Engine has now done 122K miles and is original, I've changed the cam, lifters, timing chain, push rods and rocker gear in this time but other than that, it's a good engine with no water usage at all.

Thanks

Craig.