Re: Efi injectors

In <[email protected]> alan wrote:
> Some very good information going round here methinks, but just another
> thought .Why didnt rover fit a cam sensor to the engine and then the
> injectors could open sequentially possibly giving a better control to
> the fueling (perhaps in the early days of the v8 efi around 1984/85
> there were no processors capable of operating 8 independently@
> 6000rpm ) Al

I don't think processing power had much to do with it, an engine running
at 6000 rpm is hardly fast in electronic terms. We've had devices
capable of processing data much faster than that in consumer electronics
since the mid 70's. Admittedly they tended to be based on (relatively
expensive) ASIC technology rather than CPU technology but possible none
the less.

Asking questions like that is akin to asking why a 1920's car is so much
slower than a 1970's car - they both use the same technology and you
could have produced a 1970's engine in the 1920's technologically
speaking but it was the 50 years of development and experimentation in
between that made the 1970's car possible.

The latest Land Rover EFi units use cam sensors, crank sensors and knock
sensors so not only can they use sequential injection they can change
the mixture and ignition advance of cylinders individually and
dynamically. Not just because of advances in technology but more down to
building on the legacy and experience of the systems that went before.

Land Rover have generally been fairly near to the front of technology
when it comes to EFi systems for years, especially when compared with
other manufacturers. Next time you're in a breakers, take a look at how
many manufacturers were still using carbs in the early 90's and how many
of the mid 90's cars are using variations of the flapper EFi. You'll be
surprised....

cheers

Dave W.
http://www.yorkshireoffroadclub.net/

On or around Sat, 19 Jun 2004 23:45:59 +0000 (UTC), Dave White
<[email protected]> enlightened us thusly:

>Land Rover have generally been fairly near to the front of technology
>when it comes to EFi systems for years, especially when compared with
>other manufacturers. Next time you're in a breakers, take a look at how
>many manufacturers were still using carbs in the early 90's and how many
>of the mid 90's cars are using variations of the flapper EFi. You'll be
>surprised....

Flapper EFi isn't so bad though, if once set up right. If you're not going
for a whole-hog eacH-cylinder-with-its-own-fuelling arrangement, I doubt
that such as the bank-firing hotwire is a lot more efficient. I suspect the
principal difference is that the hotwire can adjust to climate as well as
mass airflow.

the 1986 V6 Ford I have here has Bosch K-jet - which is basic,
flapper-controlled continuous injection but with electronic bells and
whistles like an over-run cut-off, full-welly enrichment and so on. Once
set correctly and driven tidliy, it can return quite good economy. 'course,
drive it flat out and you're talking low teens. Previous owner reported 19
mpg on the computer (which, BTW, measures fuel-flow and relates it to road
speed) at a steady 90 and 14 mpg at a steady 110. However, at more mundane
speeds it used to do about 27 in ordinary farting around and on a steady run
without silly velocity it's possible to get over 30. That's a moderatly
large car with a 2.8 engine, and not bad.

by contrast, the 3.5 hotwire disco seems to return about 18 in averagely
hard cross-country driving, about 16 pootling locally on small lanes. I
daresay that it'd go over 20 with suitably careful driving, without actually
driving purely for economy.

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
"The boys are dreaming wicked or of the bucking ranches of the night and
the jollyrodgered sea." Dylan Thomas (1914 - 1953) Under milk wood

In <[email protected]> Austin Shackles wrote:
> On or around Sat, 19 Jun 2004 23:45:59 +0000 (UTC), Dave White
> <[email protected]> enlightened us thusly:
>
>>Land Rover have generally been fairly near to the front of technology
>>when it comes to EFi systems for years, especially when compared with
>>other manufacturers. Next time you're in a breakers, take a look at
>>how many manufacturers were still using carbs in the early 90's and
>>how many of the mid 90's cars are using variations of the flapper EFi.
>>You'll be surprised....
>
> Flapper EFi isn't so bad though, if once set up right. If you're not
> going for a whole-hog eacH-cylinder-with-its-own-fuelling arrangement,
> I doubt that such as the bank-firing hotwire is a lot more efficient.
> I suspect the principal difference is that the hotwire can adjust to
> climate as well as mass airflow.

IMV the only real problem with the flapper system (as fitted to LR V8's)
is the cold start system. Having a n injector who's only job is to fire
fuel into the plenum chamber (almost) regardless of the engine's
requirements at that time seems to be it's main weakness. It's amazing
how many Range Rovers you see with the cold start injector unplugged.

The idle control left something to be desired too but the hotwire
stepper motor isn't without it's problems either. As you say, the
hotwire has the advantage of being able to measure oxygen content (air
mass) rather than just air quantity so should meter the fuel more
accurately. A flapper with lambda running closed loop should give just
as good a result though at cruising speed/throttle at least.

Even better would be to attach a wide band lambda and ditch the air flow/
mass meter altogether

> the 1986 V6 Ford I have here has Bosch K-jet - which is basic,
> flapper-controlled continuous injection but with electronic bells and
> whistles like an over-run cut-off, full-welly enrichment and so on.
> Once set correctly and driven tidliy, it can return quite good economy.
> 'course, drive it flat out and you're talking low teens. Previous
> owner reported 19 mpg on the computer (which, BTW, measures fuel-flow
> and relates it to road speed) at a steady 90 and 14 mpg at a steady
> 110. However, at more mundane speeds it used to do about 27 in
> ordinary farting around and on a steady run without silly velocity
> it's possible to get over 30. That's a moderatly large car with a 2.8
> engine, and not bad.
>
> by contrast, the 3.5 hotwire disco seems to return about 18 in
> averagely hard cross-country driving, about 16 pootling locally on
> small lanes. I daresay that it'd go over 20 with suitably careful
> driving, without actually driving purely for economy.

My 3.9 hotwire Disco returns around 20 on motorway driving. Main problem
is the aerodynamics and weight - my Range Rover used to return 22 mpg on
motorway runs. When I moved the engine/transmission/axles/wheels under a
110 (which is actually lighter than the Range Rover) the fuel
consumption dropped to just over 18 mpg on the same run. The only
difference is the body shape.

Have you ever thought of using a Megasquirt ?

I'm about to fit Megasquirt'n'EDIS to my 3.9 in place of the hotwire/
distributor. I spent a good part of yesterday machining a 36-1
crankshaft gear for the EDIS system, just need to make a harness up now.

cheers

Dave W.
http://www.yorkshireoffroadclub.net/