EFI for new 4.35 Rover engine.

CastleMGBV8 · Post by **CastleMGBV8** » Mon Jan 21, 2008 2:59 pm

I am trying to get some information together so to have a better basic understanding of how a EFI system functions with an alternative ECU such as megasquirt.

I have the hardware from a 4.0 hotwire system, ie Plenum, Trumpet base and manifold and a set of injectors. and some sensors on the manifold,
I do not have a throttle pot or stepper motor.

What does a stepper motor do?

I presume that a throttle pot reads the throttle position and sends this to the ECU?

So what additional kit would I need to make a Megasquirt or similar run.

I am going to be using Buick 300 heads which as a rough guide will be equivalent to stage 3 Rover heads, and a Crower 50232 cam and approx 9.8/1 compression.

Please assume I am a complete idiot as far as electronics are concerned and try to keep answers as simple as possible.

Thanks,

Kevin.

ChrisJC · Post by **ChrisJC** » Mon Jan 21, 2008 3:43 pm

A stepper motor is a motor that rotates in predefined steps, contrast with a normal motor that just rotates. It is hard to get a normal motor to move through say 15 degrees with any degree of certainly about what has happened. With a stepper, it's easy.

So you use a stepper motor for idle speed control for example.

I would say (personally!) that you need to read up loads on electronics (probably the MS site) before attempting to spec up a system.

Chris.

kiwicar · Post by **kiwicar** » Mon Jan 21, 2008 5:34 pm

Depends where you want to start, but if you are a novice with electronics I would start with a pre assembled and tested ECU, I built my MS from a kit but I spent a few years on a production line assembling cct boards

. The kit and testing are straight forward and with very good assembly instructions, but it is definatly not a first assembly kit, you need to be able to solder neatly and with components close together.
As far as sensors are concerned there is a list on either the M/S website or the MS extra site. If you go MS Extra you can get pretty well everything from the UK which makes life simple, they doo loom kits that simplifys everthing and makes for a reliable installation, also advice is at hand.
You can get full kits and looms now from the states, for MS, may work out a few quid cheeper (and I am not entirly sure of that) but you do need to know what you want far more.
You have the metalwork you need, though you need to get a throttle with a throttle pot (yes your right about what it does) and put a tapping in the plenum for the MAF sensor. I wouldn't worry about a stepper motor to start with, get the basics working first.
The basic idea in MS and other systems of a similar design is that the ECU tries to work out how much oxygin is going into the engine and squirts in the right amount of fuel to match.
To do this it needs to know how fast the engine is running, it then uses the MAF sensor to read the air pressure in the plenum with these to bits of information it takes a first guess at the volume of ait being consumed, it then looks at the throttle position sensor and uses this again with reference to the MAP sensor to work out a second guess at air volume based on the load on the engine. It then modifies this acording to air temperature in the manifold (hot air has less oxygen in it at a given MAF pressure reading) and modifies it again acording to how warm the engine is. Used like this it is "open loop" it is like an electronic carb, it does what it is told based on how you tuned it.
The system can however work tuning it's self as you go along. You can fit an oxygen sensor in the exhaust (a lambda sensor) and using that it can see how much oxygen or unburnt fuel (by products) is/are in the exhaust, it then modifies everything above so that both are at a minimum and in theory all should be running at maximun eficiency.
These are the basics, the MS site explains it in alot more detail than this and I have missed alot of detail but the basic principle is as above.
good luck
Mike

edited for the MAF MAP error described below

CastleMGBV8 · Post by **CastleMGBV8** » Mon Jan 21, 2008 6:41 pm

Chris,

Thanks for reminding me what a stepper motor does, I was having one of those senior moments.

Mike,

Again thank for the compehensive reply, just to clarify, I thought MAF was the same as a Hotwire airflow meter and MAP was Manifold Actual Pressure and that you installed a MAP sensor in the plenum to measure the air requirements of the engine, or have I got confused with the terminology.

So whats required is a throttle pot, will a standard hotwire one work? and a MAF or MAP? sensor and a wideband Lamba sensor in the exhaust to provide the basic data to the ecu, MS2? and then a basic map to start from?

I had a look at Extra EFI site and they supply ready built units and looms but don't appear to have a Tel. number and only contactable by e-mail.
have you heard of them? They do seem to have a base map for the Rover V8 which may be helpful.

There's no great rush to get the efi up and running as I can use my Edelbrock 500 and manifold whilst I'm getting the rest of the kit together.

I will fit a wideband lamba sensor when we swap the engines, as it will be easy to get at the manifold to drill and fit the required bung, and I may as well fit a 36 - 1 wheel to the front pulley at the same time so I have all options open.

Kevin

kiwicar · Post by **kiwicar** » Mon Jan 21, 2008 7:52 pm

Sorry that should have been MAP you are right about the MAF sensor being the hotwire thingy, you don't want that.
Phill Ringwood who has developed the Extra code and sells the MS-extra stuff is registered on here and contributes alot I think Bill Shuvington is also heavily involved. Both are very helpfull and can explain much better than I.
Best regards
Mike

CastleMGBV8 · Post by **CastleMGBV8** » Mon Jan 21, 2008 9:00 pm

Mike,

Thanks for clearing that up and for the info on the guys from Extra EFI.

I have sent an e-mail asking for info and prices.

I'll have to start selling off my surplus stuff to mitigate the cost of this new engine venture.

Regards,

Kevin.

bill shurvinton · Post by **bill shurvinton** » Mon Jan 21, 2008 9:21 pm

cool. Should be a mighty motor when complete.

Now personally I prefer to junk the stepper and use a Bosch idle valve as it is easier to control and as good as for most applications.

I'll ping Phil and get him to get in touch with you. For a RV8 he is the man for MS as he runs a 5litre in his cobra.

CastleMGBV8 · Post by **CastleMGBV8** » Mon Jan 21, 2008 10:57 pm

Bill,

Thanks, I'll look forward to hearing from him.

Kevin.

Nigel B · Post by **Nigel B** » Fri Feb 08, 2008 11:17 pm

I have been this route, and I also am a complete muppet when it comes to electrics

no I am trust me

I have shoved a linky to the build thread of my MS JE Rover 4.5 V8, you might find it useful, if you have Questions there are those on the site with far more knowledge than me, but if I can help ask.

http://forums.lr4x4.com/index.php?showtopic=15317

Best mod I have done, with the old JAG AFM ECU adjustable kit I had nothing but issues, MS does what it says on the tin, and I have learnt a lot, especially re tunning and tweaking. Get a grown up to build you the ECU, if I had done it it would have looked like a watch repaired by the incredile hulk, its a skill - and I do not have it

HTH

Nige

CastleMGBV8 · Post by **CastleMGBV8** » Fri Feb 08, 2008 11:30 pm

Thanks Nigel, I'll bear that in mind for when I start putting the EFI together,

Kevin.

JSF55 · Post by **JSF55** » Fri Feb 08, 2008 11:35 pm

Well i joined that group just to look at that page ...well all 11 in fact it's avery good write up sent me in the right dirrection for a few bits i needed to finish my assembly, just waiting for Phil to build me mine

CastleMGBV8 · Post by **CastleMGBV8** » Sat Feb 09, 2008 12:09 pm

JSF55 wrote:Well i joined that group just to look at that page ...well all 11 in fact it's avery good write up sent me in the right dirrection for a few bits i needed to finish my assembly, just waiting for Phil to build me mine

I had a quick read last night and it would appear very helpful, have save it to favourites in my EFI folder so I can find it again for when I am going to swap in the EFI.

Kevin.