how to work gems ecu in rrc without becm?

[bobtailrangie]

Hi guys

I picked up a pretty well kitted 72 bobtail couple weeks ago + planning on a gems 4.0 engine swap

Its going on a manual box so ive sourced a manual flywheel for crank position sensor

From my knowledge + the very few things i can find online is the only thing stopping gems ecu working in another vehicle is the immobiliser as its switch off by the becm

This is not an issue as i have found a company who will remove immobiliser for £95 + they also say its all that stops it

What i need to know is does anyone know anything about wiring it to work or anything else needed?

I assume ill need all 4 lambdas still?

I dont realy have the spare cash at the moment for megasquirt + if i can do this it works out an awful lot cheaper for the same final outcome

Thanks in advance

James

[elbekko]

It should only need two lambda's, you may need to use a Rovacom or similar to tell it it's in another market though.

Apart from that, it shouldn't need much. Have a look through the RAVE here: http://rave.stringsandints.com/RR%20%2702%20-%20RR%20P38%20-%20Defender.rar

It lists all the in- and outputs of the GEMS ECU, most of which aren't really needed.

[Escape]

GEMS can even run open loop without lambda's. As Elbekko said, you need to program it to the appropriate market settings. If you leave the lambda's disconnected, the GEMS will log an error code, but will revert to open loop and keep things running. It won't be very good at coping with modifications without the lambda's, because it has nothing for feedback.

Wiring shouldn't be to hard. And if I'm not mistaking, the immobiliser can be disabled in the settings as well.

[Hybrid_From_Hell]

To get the GEMS unit to run outside the donor vehicle you will need to have the ECU hacked with esp the imobizer shut off and some other inputs fudged so the sytem doesn't generate fault codes and trip limp mode.

Its doable, it has been done, but its not a great solution.

Check out prices for the MAFs (suggest sitting 1st), the trigger wheels can loose prongs, the wiring is somewhat "Vast" and really you need to strip the loom down and get rid of much that could cuase issues etc when / if you hack the ECU.

Even then you'll have a ECU Mapped for a engine / config / setup that doesn't match what you have now, cats for example, also these engines are underfuelled and over hot for running (to aid emmissions) and cat'ed as well, all of which means you loose the opportunity of getting proper performance out of them ..

And it won't end up a cheap "Fix" either, and if anything goes wrong on your ECU is rehack remod time....

To get the engine both running AND performing as it can you'd need to have a EPROM Fitted instead of the RAM chip, and have it properly programmed, and I would say lower the thermostat to a 84 degree on too,

Another way is to find a complete 3.9 Hotwire Loom and ECU and with 4 wires and a tune resistor tweak it will run, and 4.0 / 3.9 are the same really ...but again a EPROM would be a better fix.

All in all go for it, but bear in mind its not that cheap, esp if you get it all done properly vs "Running"

Personally if you didn't wnat to go MS I would swap to the hotwire system, injectors are the same, you just need Loom, ECU MAF Road speed Tranducer, you can keep inlet / trumpets injectors / rail but swap the plenum for the 3.9 Stepper.

Nige

[bobtailrangie]

Thanks all for the replies

Its seems its not too costly or difficult to get it running in a basic way but not 'properly'

I knew the cc on the 4.0 was same as the 3.9 but wasnt aware the 4.0 was also run lean like the 4.6

Ill still go for the 4.0 as its the serp belt setup im after, the are cheap + plentiful + i want a waterproof v8 so things are pointing down the megasquirt route anyway after some of the things nige has pointed out

On the up side the 4.0 serp is the cheapest megasquirt kit anyway

Thanks again