4.6 GEMS into Defender 90"

[Off Road Toad]

Hopefully someone can help. i'm probably opening a can of worms here.

THE PLAN:

To replace an old non serp pre-cat 3.9 efi v8 with a 1997 cat type 4.6 gems engine.

THE PROBLEM:

I need to run cats as the vehicle is 1998.

I'm putting it in front of a R380 as it's already there, so i have the problem of flywheel sensors?

apparently also according to RPI i have to have the gems ecu chipped at a cost of £700.

What would those of you who know far more than me about this do?

I like the idea of not having a dizzy, ie using the gems system preferably.

thanks, Steve

[FridgeFreezer]

Megasquirt.

Do you *have* to run cats or have you just been told you have to because of the GEMS system?

[Dave W]

Megasquirt...

[Dave W]

On the CATS thing, if the engine is older than the vehicle then the age of the engine determines the requirement not the age of the vehicle, emmission requirements work that way too.

I can't remember when they were made mandatory but I have a feeling it was 1998 in which case the 1997 engine doesn't need them.

[TheRecklessEngineer]

Megasquirt...

I think there may be a few more posts like this

[Off Road Toad]

Right then! Megasquirt it is then.

RE: the cats, I've had interesting dealings with the mot people over this.

the car is 1998 so would need cats fitted based on manufacturing year.

The engine is fitted with cats from factory and so needs to retain cats for the mot.

regards the old engine, i got away with this (non cat engine) as the engine number corresponded on the "computer", i replaced the block with a later one and the engine number said it was a cat type and so failed the mot.

So: so that i dont have grief at mot time i'm going to keep the cats.

I spoke to simon (of x eng fame) about megasquirt and he convinced me it's the way forward.

So next question, where from? simon suggested you might be able to point me in the right direction Mr FridgeFreezer?

Thanks for the advise

Steve

[chuck]

Steve,

I run a 4.6 Gems in my tomcat... with a few tweaks it's possible to get the gems working nicely.

Only the NAS spec 4.6's had o2 sensors before and after the cats. UK only had them before so the GEMS won't mind you not having cats.

I used a (£20 from ebay) 10AS security ecu from a disco for immobilization (i suspect that £700 charge from RPi includes removing the need for immobilization)

you'll also need a road speed sensor input to stop it from cutting out when your rpm's drop - I took a feed off my terratrip speedo cable probe and it worked a treat.

lastly you need some resistors for fuel level input and purge cannister outputs - these were kindly supplied to me by Mark Adams when i bought one of his chipsets.

I use an LT85 box so i had to get the Gems style flywheel with relcutor ring on it (can't find the part# right now) and the corresponding crank sensor ERR6357 (different to the auto).

Used rovacom with the gems module and 10as module to match up the immobilization codes on the 2 ecus and switch the gems setting from auto to manual.

I even extended the engine wiring loom so i could mount the gems inside the cab. In all the set-up works well and is fault code free

[V8 Freak]

Steve,

I have a 4.6 (no cats) in my Defender. Originally on Omex but recently converted to Megasquirt after much thinking and wondering.

Sensor wheel on the front crank and still serp front end. I've added in closed loop idle control and the engine now runs very well, smooth, easy to start from cold and still loads of power when needed.

It's transformed the engine and I would highly recommend it.

Neil

[Dave W]

On the sensor side of things, it's probably easiest/cheapest to add a 36-1 to the crank pulley with a VR sensor. As well as giving you the option of EDIS or direct ignition control with Megasquirt it's also compatible with numerous other after market ECUs.

You can use the OEM reluctor/sensor with Megasquirt without any problem if you can find a suitable way of adding it with a manual gearbox.

As for suppliers, there is a list here...

http://www.msextra.com/viewtopic.php?f=94&t=22372

If you consider buying one off ebay there are a couple of warnings here (as well as useful info about MegaSquirt in general)...

http://www.msextra.com/viewforum.php?f=94

[western]

Steve,

I have a 4.6 (no cats) in my Defender. Originally on Omex but recently converted to Megasquirt after much thinking and wondering.

Sensor wheel on the front crank and still serp front end. I've added in closed loop idle control and the engine now runs very well, smooth, easy to start from cold and still loads of power when needed.

It's transformed the engine and I would highly recommend it.

Neil

good to see ou made that big V8 run properly at last.

[Aragorn]

I'd just use the onboard crank sensor/trigger ring and run wasted spark direct drive from the megasquirt.

You'll already have the coilpacks etc on the gems engine.

[FridgeFreezer]

I'd advise against direct drive unless the coils also have ignitors on them, it's a PITFA to set up & make work reliably. EDIS just works.

[Hybrid_From_Hell]

Plus

Megasquirt normally has Front Pulley mounted Trigger wheel and VR Sensor, GEMS

has it inside the bellhousing on the rear of the engine crank, a giant PITFA

to change if it goes wrong vsMS on the outside on the crank pulley

Nige

[Dave W]

Plus

Megasquirt normally has Front Pulley mounted Trigger wheel and VR Sensor, GEMS

has it inside the bellhousing on the rear of the engine crank, a giant PITFA

to change if it goes wrong vsMS on the outside on the crank pulley

I think you're over-egging the pudding a bit there. The GEMS sensor and wheel/pegs are encased inside a purpose built housing that keeps them, for the most part, clean and mechanically protected. The chances of a GEMS set up going wrong are extremely small and the most likely point of failure is the sensor itself, which can be changed easily and quickly in situ.

If it weren't for the "standard" 36-1 giving you more options when it comes to ECUs there would be very little in favour of making your own wheel/sensor to bolt onto the most exposed part of the engine. Normally on any engine fitted with an OEM sensor I'd use that if possible over something I bolted on myself. The only real reason for considering an additional wheel in this case is that of cost/availability of the modified flywheel when you're using a manual box. If it were staying auto then IMV it would be a "no brainer".

Obviously if you're looking at a hybrid MegaSquirt/EDIS setup then you have no choice but to bolt your own wheel and sensor on the front because the EDIS won't work with anything else but that's a different issue.

[Aragorn]

I dont really think the problems with direct drive are as bad as fridge is making out.

Its the most common option on motors other than the RV8, because EDIS can only really be used with 36-1 and seen as most other cars already have trigger wheels like the bosch 60-2 etc direct drive is the more sensible option.

There is tonnes of info on direct drive wasted spark available, and bar setting up the dwell time its not really that difficult.

Its all the little things like using the correct resistor spark plugs that will ensure you dont have any problems.

As Dave says, the onboard crank sensor ring will be more robust than something nailed to the crank pulley, and the sensor is changable externally.

You can either use something like the Ford coils but using 4 onboard spark drivers (BIP373's are pretty popular just now), similar coils with an external ingitor setup (units from mitsibushis are common, as is the bosch 211 used on the early VAG 1.8T's) or LSx style coils with integrated ignitors etc.

I'm looking into a coil pack used on small block vauxhall I4's which has onboard ignitors, and are common as muck in the scrappys, i just need to work out what kinda signal it needs to drive it. Trying to borrow a scope so i can look at what the vauxhall ECU sends them.

[FridgeFreezer]

I dont really think the problems with direct drive are as bad as fridge is making out.

Direct drive does work (they wouldn't have put the option on the board if it didn't) but takes a hell of a lot of setting up and is subject to interference issues as you have the high voltage flyback EMF from the coils inside the ECU (especially on a V8 where you have four coils to drive), which can cause processor resets. You absolutely must use a separate ground for the ignition drivers, which means adding an extra plug to the ECU and running in extra wiring.

Edis will just work.

You get no benefit from direct drive other than hard spark cut rev limiting (you still have ignition retard/fuel cut limiting with EDIS).

The third way is direct coil drive using coils that have the driver in the coil (a-la LS1) as that moves the high current & interference outside the ECU.

[RedLineMike]

Steve,

I have a 4.6 (no cats) in my Defender. Originally on Omex but recently converted to Megasquirt after much thinking and wondering.

Neil

going from omex to megasquirt seems a bit like a back step TBH

[V8 Freak]

going from omex to megasquirt seems a bit like a back step TBH

If you have nice big pockets to keep tuning Omex when any engine amends are made or the engine is a highly specc'd fussy thing, then Omex would be great.

Although a top piece of kit, you can't home tune it and getting advice is pretty darned hard. I figured a lot of table inter-relationships from a lot of reading and built Map models in Excel which worked very well, but when it came to adding closed loop idle, improving cold starts etc. Omex could do it, but getting it there would cost more than kitting out with MS.....

Hence the change.

Now runs better than ever before since I had the engine, and It's hardly been tuned yet ! Horses for courses I guess....

Neil

[Aragorn]

Fridge, the drivers dont have to go inside the ECU.

You can always run the logic level outputs from squirt to a box in the engine bay, and put the BIP373's in there, with suitably meaty connections for power and earth etc.

It might be a little more tricky to setup, but when the crank trigger etc is already there, it is a viable option imo.

[FridgeFreezer]

going from omex to megasquirt seems a bit like a back step TBH

How so? I've not yet found anything worthwhile any of the commercial ECU's can do that MS can't, apart from charge you lots of money.

[Aragorn]

I think one of the biggest things MS has going for it from reading the Big Megasquirt Thread, is its mapping ability.

Most commercial ECU's are designed in such a way that its only really mappable on a rolling road, where you can hold the engine at a particular site, and adjust the settings before moving on. Theres nothing particularly wrong with this, bar needing a rolling road, which is expensive to hire for a few hours and not even worth considering as a purchase, not to mention that most RR's will want it operated by their man, so you cant even just rent the cell and use it to map it yourself.

'squirts ability to drive around on a bad map, log the problems then easily apply the corrections based on a target AFR table is pretty unique as far as i know.

It is also very flexible in terms of what extras it can drive, and being open source you can easily solder in new circuits to make it do things that are quite special.

The only feature that could be said to be missing is proper traction control. Its rare even in aftermarket ECU's though, only Autronic SM2 can do it properly (ie 4 wheel speed inputs etc) afaik.