Efi or other car alternatives

R

Richard Thorley

Member
When I've been bord and started messing about in ebay I've seen rover efi set ups come up for sale and wondered about fitting one to my 3500S (it already has sd1 heads). I guess it's not an easy upgrade or everyone would do it but how in depth a job is it an what would you need. Or is it just that the Standard SU set up is just right. I've been to lots of shows and compared to other classics I've owned P6s are often seen standard. It would be nice not to have to mess with chokes anymore though, and an improvement in fuel economy would'nt upset me either
 
Reality is you would be unlikely to see much if any economy improvement. The only realistic way to do that if you haven't already is fit a 5 speed gearbox. Some people who fit the Weber 500 setup have reported better fuel consumption - I have no experience.

Trouble is anything that improves performance, especially throttle response will generally encourage you to drive in a less economical way anyway, even if it does improve efficiency. Remember a 10% improvement in economy is barely 2mpg anyway....

I've looked into this quite a bit as I'd like to do it anyway. The basic fitment doesn't look too difficult with the Hotwire setup from Land/Range Rovers which is much better than the "flapper" on the Vitesse. You'd need a higher pressure pump and fuel lines and probably some land rover adapted aircleaner and really that's about it as it is fairly self contained. Ideally you'd need also a speed input to switch idle mode and a custom chip as only a few Discoverys had a 3.5 with EFi. Standard fuelling maps tend to be very conservative anyway and have been improved on quite a bit, especially as you have a much higher compression engine. I believe fitting more modern injectors with a better spray pattern is rumoured to give an extra 1 mpg also

The main result of a well done conversion would be a much better car to drive, particularly throttle response and it'd run cleaner but the general consensus is that can pretty much be done (emissions aside perhaps) with the Weber setup.

SU are brilliantly simple and very efficient when matched perfectly to the engine. The weaknesses are threefold really. Firstly they are constant volume and not constant mass devices so they don't adapt to pressure (including altitude) changes. Secondly they give poor throttle response as there is little in the way of "pump" effect as you get with US downdraft carbs and finally because they are so closely matched to the engine, almost any minor tuning changes mean you need to look at adapting the jet to suit. EFi with adaptive, mapped fuelling fixes all of these.
 
It's fairly involved, and if you go the megasquirt route, you then have to learn how to tune it, which is even more involved. Companies like RPI will develop a custom chip for your ecu which would be easier, but I was never really happy with RPI so I went megasquirt.

Quagmire fitted his system in a very short time but then he is an expert, and I was a complete novice. My 3500s project - future daily drive

The finished article is however quite astonishing. When I bought Sparky, the engine was made up of various Rover V8s and some tuning goodies, some of which made it torquier, and others which made it revvier (if that's a word ?). The 500 Weber and the Mallory dual spark never really suited this make up and I never really got it set up right. The EFI has transformed the engine.

Go hotwire though, don't go the flapper route.

Richard
 
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And the fuel economy Richard? Little/no different I'm guessing?

What would you say were the main difficulties?
 
PeterZRH said:
And the fuel economy Richard? Little/no different I'm guessing?

What would you say were the main difficulties?
Click to expand...

Fuel economy with the Weber was around 28mpg on a long trip, sometimes up to 30mpg if the wife was in the car :). Low 20s at the moment but then I haven't been on a long trip and motoring in Sparky at the moment is tuning, so up and down the rev band, and driving to work in heavy traffic. Also, he's very revvy now and is a joy to whizz through the bends :D vrooooooooommmm

Hard bits were working out where to fit everything, and actually getting them to fit there, e.g. fuel pump fitted into a hole I drilled into the top of the tank, but the pick up was in the wrong place, so I had to modify it. The kit I bought wasn't for a P6 so all the brackets needed to be modified, I'm crap at soldering tiny wires into tiny holes, and tuning was very complicated. Very satisfying when done though and there are forums who are helpful.

Richard
 
what did you end up doing with the existing tank outlets ie main and reserve lines at the tank end?

Graeme
 
ghce said:
what did you end up doing with the existing tank outlets ie main and reserve lines at the tank end?

Graeme
Click to expand...

I blanked one off and used the other as the return pipe. I do need to take it out again soon though as I had to bend the boom on the fuel guage to get it to fit, and now it doesn't work :oops:
 
Richard is overstating my abilities a bit!:p Happy amateur probably covers it better.

Based on my experience with Megasquirt, fitting EFI and crank triggered ignition will give you many things:
  • Great starting in all weathers
  • More consistent running - no carbs to keep cleaned/topped up with dashpot oil, no points to check or set, and no dizzy cap to wear out.
  • Better power. On a Pistonheads trackday at Silverstone I had a couple of Rover V8 bashers/haters openly say after I had been round that they were impressed at the power it must have been putting out. My engine is standard apart from the MS and ten bolt heads.
  • Better economy - i get anything up to 27.5mpg on a run (with a four speed box), 24-25mpg in stop/start traffic. See my fuelly stats for details.
  • Engine oil seems to stay cleaner between changes
  • You can add outputs to control external items via relays - for example an electric fan. You can then set the conditions to trigger that output however you like.
  • With Megasquirt and Tunerstudio you suddenly have access to a lot of data on how your engine is running
  • You can tune your car in your Sunday best - changes are easy to make on your phone or laptop and can be made "live" whilst you run or "offline" and uploaded to the car later.
However:
  • There is a fair bit of reading involved, running an engine in a satisfactory way through all the changing states it experiences over the course of a day involves many theories, a lot of which interact with each other. Understanding these is key.
  • Like any computer based system it will only do what it is told and so junk settings in = junk performance/behaviour out.
  • You will need to be able to read and understand a circuit diagram in order to wire the car.
  • As Richard says, figuring out where to put everything can be tricky - the ECU, extra fuses, the loom, fuel pumps, filters etc.
  • The most cost effective way of going over to MS is to build the ECU yourself. It's straightforward but you need a steady hand with a soldering iron and some basic knowledge of electronics (my highest qualification is an Electronics GCSE from many years ago).
  • Fitting the MS and getting the car to fire up is just the start, the fun (but sometimes frustrating) bit is the real tuning that comes after this. For example, talking only fuelling for now the following give an idea of what needs to be setup:
  • Basic details about your engine and injectors - displacement, cylinder count, firing pattern, injector flow rate.
  • Cranking fuel pulsewidths (pulsewidth vs coolant temp) - these are the pulses of fuel that the car will first start on while it is being cranked over.
  • After Start Enrichment (ASE) - the extra fuel that is added on top of other requirements once the engine has come out of cranking mode and into run. The ASE stabilises the engine during the first few seconds of it starting.
  • Warm Up Enrichment (WUE)- the extra fuel that is added whilst the engine is cold.
  • VE table - the base values of how much fuel the engine requires for any load vs rpm situation. This is assumed to be at normal temp and in a steady state condition.
  • Acceleration Enrichment (AE) - how much momentary extra fuel does the engine require at various different rates of throttle depression
  • Overrun fuel cut - when should the injectors stop delivering fuel entirely
  • Exhaust Gas Oxygen (EGO) control - how quickly should the system alter fuelling based on feedback from the Lambda sensor? How much can the system add or remove at any point?
All of those will need some input from you to make things work properly.

For ease of typing I have tried to follow through in a logical way from turning the key. However the reality is that you should get your basic VE table tuned first as the other fuelling parameters are basically multipliers/modifiers of those base values.

I would recommend doing a bit of reading and deciding on what you want to do and how you want to do it. For example you could run fuel only first and add the fuel injection side later or vice versa. When I installed mine I already had Megajolt fitted so it made sense to go ignition only as a first step. Once I was happy that everything worked ok I then added the fuel side.
 
Lucas 14cux Hotwire setup is pretty self contained, and most of what you need is in the engine loom. There's about 4 wires to get it to run from memory. I have a Hotwire 3.9 in my early Range Rover that was previously carbs. You'll need a high pressure fuel pump and a return to the tank with a filter before the pump. Ideally the pump should be low down and near the tank but the one in the Range Rover seems to work ok on the inner wing. You need a permanent live to the ECU, an ignition switched live, a connection to the coil so the ecu knows the engine's running and a wire from the engine loom to feed the fuel pump. There's an ecu and a few relays to package somewhere safe and dry. Ideally you should have a speed signal from the speedo cable, but this isn't essential to get it to run. The Range Rover seems fine without this. If you connect this, the maximum speed will be limited. For safety, the fuel pump should be fed through an inertia switch. If the set up came from a car with catalytic converters, you'll need a different tune resistor to run without cats. There's a pin on the ecu loom to run a check engine light, maybe use the old choke light? There's also a pin that causes the revs to raise at idle. Useful on an auto so the engine doesn't stall when it's in gear, or for cars with AC.

In my Range Rover, the engine's really tractable. It will pull from almost stationary in 3rd, so long as there's some movement it's happy. Starts can be made in 2nd without the throttle just by letting the clutch up lightly. The ecu just adjusts the air bypass stop the engine stalling.
 
I believe the speed input as well the limiter changes the idle speed below about 3mph. The 14CUX will run without it but what is the collective opinion on fitting and wiring the lambda probes? In general from what I've read this is a good idea particularly if you haven't got an optimized fuel map as it will self-tune (obviously they are essential with cats)
 
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