MSefi.com read only forum (Jan.15,2018)

My project car has a brand new unused very early Rover 3.5 EFI engine, janspeed exhaust, torquemax cam. It has to run on petrol and LPG. It uses no lambda sensors or anything like that, and currently has flapper AFM.

Can someone please explain what variant of megasquirt I need, to give me good starting, economy and adjustment for LPG.

This is not a race car it is to be used for long distance towing. In the first instance I would like to get up and running with minimum fuss, and a realistic budget.

Advice would be really valued.

Can't help with the LPG bit, but can give you some guidance for the RV8 with flapper injection.
It relies mainly on the flapper unit to set the fuelling. These wear out, and are getting difficult and expensive to source new. As are the throttle pots. The ECUs can suffer from dry joints. Non of which is surprising given they can be more than 30 years old.

MS doesn't use the flapper - it senses load by using engine vacuum via an internal sensor.
It can use any TPS you can make fit mechanically.

Any MS ever made will replace the Lucas ECU and give at least as good results as a perfect Lucas system, and in most cases, very much better, as production tolerances seemed to make these vary quite a bit even when new. Before I fitted MS to my SD1 EFI auto, it had always felt rather flat at low to medium revs, but excellent if you floored it. I fitted a wideband sensor before the MS, and the reason became clear. It was simply running too weak at low to medium revs on other than full throttle. And if you floor an auto, it will kick down. So was all or nothing. With MS, it now pulls like a train from low revs - just as you'd expect from a V8.

So if all you want is the direct equivalent of the Lucas system, but working as it should, an MS conversion is going to be very cost effective and easy. That is assuming you have reasonable wiring skills and DIY. I have no personal experience of pro fitting, but it's obviously going to add considerably to the cost.

Problem - if it is one - with MS is the variety and what they can do. There is the 'while I'm at it' syndrome. Mapped ignition. Sequential injection. Better fast idle etc control. And so on. Although these can be done in stages. B&G code - this site - will be just fine for the basic installation. If you go for the more esoteric, you'll need Extra Code, covered on a different site which you'll find a link to on this page.

I started out with an MS2 running fuel only about 7 years ago, and it ran well. After yet another ignition amp failure change to EDIS. And so it remains to this day. But I've got an MS3 and sequential injection waiting to be fitted.

I would advise you budget for a wideband O2 sensor system. It takes all the guess work out of tuning.

Really, you need to decide for yourself what you want and are willing to spend.

Obviously I don't have an O2 sensor at the moment. Presumably these are fitted into the exhaust but do I need to fit them to both manifolds or can I fit one after the Y piece where it would be much easier to weld a boss on.

I am happy to change the flapper for a hot wire sensor as long as I can find one which will interface with the LPG distributor, but are you saying that MS uses a vacuum sensor instead of a hot wire AMF unit.

Fitting and wiring is no problem at all, but I'm not sure that I want the hassle of setting up mapping etc, I assume by now someone has decided on the optimum for a 3.5 efi. If I buy a prebuilt and tested unit will they install the correct mapping.