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Megasquirt opinions of the wise and learned.


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Hi all.

I've spent so much of today reading about this that I've got the word "Megasquirt" burnt into my retina, and that mass of wires from HfH's photos mid-install will haunt my sleep. :blink:

I'd like to ask the wise and wonderful their opinions on a few things.

Here's the setup that I'm considering:-

Serp/GEMS 4.6 from a P38, with the HP24e gearbox.

MS, running a switchable map for petrol and LPG, and using the standard ignition, and LPG injection.

I'll be doing as much of this as is possible myself, as I'm delving into the dreaded overdraft as it is...

I've asked Monsieur Fridge for the esteemed Mr Shuvington's contact numbers, so will be asking him a lot of the bigger questions. What I'd like from you lovely lot is more along the lines of experiences/opinions.

Here's my questions:-

1). Am I doing the right thing here? (I think I know the answer to this one... ;) )

2). Is there a blindingly obvious reason, that I've missed, for me not to use the ignition all ready on the engine, controlled by the 'squirt?

3). What injectors for the LPG should I be looking at? Who's got what, where from, and why?

4). Will this system work with the brain of the ZF 'box? Is there anything that I need to know about this bit?

5). What the f have I let myself in for?

I'll await the replies with a healthy sense of trepidation.

Cheers,

Jake

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First off, Mr S is quite a busy chappy at the moment so I doubt he's got time for MS related stuff. If you want an ECU, Nige is your man these days 'cos I'm too much of a grumpy b*****d to sell them to the public :ph34r:

1). Am I doing the right thing here? (I think I know the answer to this one... ;) )

I couldn't possibly comment :P

2). Is there a blindingly obvious reason, that I've missed, for me not to use the ignition all ready on the engine, controlled by the 'squirt?

Yes, it's a pain in the arse. Use EDIS.

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4). Will this system work with the brain of the ZF 'box? Is there anything that I need to know about this bit?

I'm not sure if it works with the ECU of the AT as I don't know what is installed on the RR. On BMW's which are using the same AT the TCM as it's called there (made by Siemens) won't work.

IMHO you have two options: Contact Dave Ashcroft for a 4HP24 that is hydraulically controlled only (I think he reworks them) or (and this is the one I'd prefer at this point of time) contact Dave Ashroft for Compushift. This is a free programmable ECU that fits on the 4HP24.

The third option is to wait at least 18 months - then you might be able to control the 4HP24 with MegaSquirt. At the moment there are no codes available for this type of AT (just for some US AT's) but I know some guys working on it...

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1). Am I doing the right thing here? (I think I know the answer to this one... ;) )

Probably :)

2). Is there a blindingly obvious reason, that I've missed, for me not to use the ignition all ready on the engine, controlled by the 'squirt?

Not really, you can use the OEM crank sensor straight into MS and drive the ignition packs direct. Personally I prefer to make a small "driver box" to contain the actual coil drivers that can be mounted near to the coils. By doing that it reduces the risk of "noise" at the ECU caused when you are switching the coils from the ECU. Mounting the drivers inside the ECU case is messy by comparison and can cause problems with noise in the loom and internal to the ECU due to the current fluctuations when switching coils.

3). What injectors for the LPG should I be looking at? Who's got what, where from, and why?

As it's a GEMS unit I wouldn't bother with a sequential injection style LPG but, instead use a single point one. I use Tartarini for mine, in no small part because the UK distributor is 30 mins down the road and they've been extremely helpful in the past. i also have the cable and PC app that lets me plug into the LPG ECU and adjust it if needed.

4). Will this system work with the brain of the ZF 'box? Is there anything that I need to know about this bit?

This is where things can get complicated. The simplest solution (if not the cheapest) is to use an aftermarket ECU for the gearbox. The Compushift ECU from Maddison4x4 (re-sold by Ashcrofts and Devon 4x4 as well) will allow you to run and program the gearbox fairly easily. If you're on a tight budget you may be as well to put a hydraulic version of the gearbox in. I've not looked recently to see what the current status of the gearbox ECU from Bowling and Grippo is at the moment.

5). What the f have I let myself in for?

As long as you're methodical in your approach and don't over complicate things you shouldn't have any major problems. It can seem a bit daunting when you first get started but, at the end of the day, it's all simple enough if you take it one step at a time.

MS3 is still a bit "cutting edge" at the moment but MS1 and MS2 will both handle everything you need quite happily. If you go with MS2 you can control the OEM idle air valve direct and the closed loop idel control seems to work pretty well on the later code versions. Personally though I prefer to stick with the Volvo air valve as it's cheap to buy new and can be run with any version of the MS hardware. MS1 is also cheaper than MS2 and without the stepper valve to control you have enough spare outputs on the standard DB37 connector to drive the coil packs through it (assuming you use a remote driver box).

I've found the simplest way of switching maps when you go onto LPG is to use the solenoid output from the LPG ECU and configure the MS hardware to trigger the secondary fuel and ignition maps when you get 12v at the input. I then set this up with a 0.4 second changeover time.

Most of the above assumes you are using an independent LPG system/ECU, I've not tried driving LPG iojectors direct with MS myself as the LPG ECUs always seem to be such a minor part of the outlay. I have spoken to the tech guys at Autogas 2000 about driving a Tartarini injector system in the past and there's no real reason why it wouldn't work... just not something I've tried myself.

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