e30 M3 minor rust repair.

[95///M3]

Any new updates?

[PGAero]

First of all, absolutely love this thread.

I'm pretty sure Saab has used COP since '93 (my '93 9000 Aero had them, but I don't know if they did it any earlier). They also used the spark plug as a knock sensor, allowing their high output turbo engines to run on low octane fuel if needed. Turbo pressure was simply dialed back until no knock was happening. Of course, this meant less power, but it also meant you won't wreck an engine because you couldn't find (or didn't purchase) high octane fuel.

As Corvallis mentioned, multiple sparks can be produced and timing can be very tightly controlled.

~Peter
'89 325iX
'04 9-5 Aero Combi

[CorvallisBMW]

All cars now days use COP; it's much less expensive than a distributor/rotor/wasted spark system as it requires no spark plug wires ("leads") and needs merely an ECU trigger to fire. Timing is very tightly controlled, often with 4 or 5 individual sparks firing off within the millisecond to ensure complete ignition and combustion. It also simplifies the construction on the engine and means only 1 part is needed (the COP) instead of a myriad of different parts doing different jobs (coil, rotor, distributor, etc)

[Massimo]

I don't know the percentages, but, if you pop the bonnet on most
mass production cars these days you'll see a wasted spark
coil setup. Individual coil on plugs (cop) seem to be reserved, for
the most part, for high performance models. I've yet to learn what
,if any, performance advantage the coil on plug setup offers.
I'd imagine theres some reason for it though, they seldom tend to
do things for the craic.

Not much really besides what was mention before about possible residue in the exhaust stroke. They also allow long charge time extending the life of the coil, apparently. The new BMW S65 has knock sensors build into each COP. The only other advantage is you never need to replace leads.

The residure in the Exhaust stroke should not be a problem with a well designed engine. If you have designed your engine right you should have 100% burn at the end of the power stroke.

[xworks]

I don't know the percentages, but, if you pop the bonnet on most
mass production cars these days you'll see a wasted spark
coil setup. Individual coil on plugs (cop) seem to be reserved, for
the most part, for high performance models. I've yet to learn what
,if any, performance advantage the coil on plug setup offers.
I'd imagine theres some reason for it though, they seldom tend to
do things for the craic.

[monoi]

Harley engines used to have wasted sparks, and it was a common mod to go single spark as apparently, burnt gases are not necessarily entirely burned and therefore you could have some more combustion on the way up which would not help.

Thinking about it now, it sounds a bit far fetched.

[Car Addict]

oohhhh SHMEXY cant wait for next update. Great work as always

[xworks]

To say I was a little nervous doing this would be an understatement.
These leads cost a bloody fortune, and probably the best way of describing
the tense nature of the moment would be to imagine yourself removing
one of these from your person........



with one one these........



Many cautious hours later..........







And now with that little bit of insulation removed from each lead all four
could comfortably fit in place on the coil..........



bit of rerouteing of the leads back into their tube...........



and thats the ignition side of things sorted.........



Next up will be the fuelling.
Till then...........

[xworks]

and bingo, we now have somewhere for our new coil to mount........





If I'm to be honest, this took a bit of smoke between the ears to figure out
as the coil needed to be in just the right place for one simple reason...........



I wanted to be able to use the standard HT leads without having to
get a custom length set made up..........



Thats not to say the standard leads were a straight forward fit with the new coil,
obviously there'd be no fu*king fun it things went that simple. A little problem
had to be taken care of before they sat into place. Each lead was removed from the
carrier tube............



And a small section of the insulation rubber on the coil end connector had to
be removed..........



with a very sharp knife...........

[xworks]

Before we kick off this update it's probably worth mentioning that I've had a very
polite e-mail informing me that I've somehow managed to make a complete balls up
of explaining how a VR cranksensor actually works in the last update.
So, I've taken the time to do some intensive research into the workings of a VR sensor
and get a better understanding of it, so that I might be able to pass the knowledge on.

The VR sensor works by................................... nah, still can't figure it out.

Moving on..............

With all the main inputs taken care of, the ecu can now get it's arse in gear and
start to earn it's living. Once it's checked over the incoming sensor info it
can then decide how much fuel to squirt in and when to fire the spark.

First up for us is the spark.

With the standard management system there's quite a few components involved
in the job of getting the spark created, and then, carrying it down to the sparkplug
to set off the bang.
First up, the standard ignition coil......



The coil is fed a constant 12 volts once the ignition is switched on and
then the ecu switches the coils earth wire on and off to create a nice fat whack of voltage.
Once the ecu has trigged the coil the high voltage travels out and into the high tension lead.........



Which carries it all the way up the the distributor cap, whereupon it enters through the bottom
port..........



Once at the distributor cap the voltage travels inside and passes
over onto the centre of the spinning rotor arm............



As the rotor arm is bolted onto the end of the camshaft it's spinning around
with the engine. And once the tip of the rotor arm lines up with one of the
brass poles on the inside of the distributor cap the voltage takes a leap
and is off on it's way again.........





After jumping to the brass pole it's off out to that cylinders HT lead.......




(picture borrowed from Google)

And finally after travelling down the HT lead it reaches the sparkplug,
where upon it completes it's journey by jumping to the earth probe of the sparkplug
and the resulting spark lights the booom.......



I know, I know, pure Einstein stuff, but bare with me.
All of this works perfect on a standard engine, and, even a highly
modified one if the truth be told.
So, as you'd expect, I've gone an fu*ked with it.

What you see below is what's sometimes referred to as a "wasted spark"
coil........



As the new Dta ecu now fitted to the car gives me the option to use one
of these I'm going to run with it.
Probably worth a few words on how it works before explaining why I've chosen
to go this route.
The coil shown above while looking like one chunky fat unit is
actually two separate coils moulded into one unit.........



The ecu can either trigger a spark from the red coil or the green coil.
As you can see in the pic above each half of the coil has two connections
for HT leads. The leads for cylinder 1 and 4 are connected into the green
half and cylinders 2 and 3 into the red half......



When a spark is required in cylinder 1 the ecu fires the green half of the coil
and the two leads plugged into this half both get the large whack of voltage.
The result is both the sparkplugs in cylinder 1 and 4 fire at the same time.
The spark for cylinder 1 arrives and sets off the ignition of the compressed
fuel and air in this cylinder, while further down the block the spark also
arrives in cylinder 4. However as this cylinder is just pumping out burnt exhaust
gases at the moment when the spark goes off it does nothing.

This is the same process every time a spark is needed. The ecu will trigger
whichever half of the coil that sends the voltage to the sparkplug that needs it,
and, it will always travel down the other HT lead connected to this half of the
coil aswell. The voltage that travels down the other lead will always create a spark
in a cylinder thats pumping out exhaust gases and as such will be wasted.
Hence the nick name for this type of ignition system, "wasted spark".

So, thats how I think it works, as always xworks enterprises can not be held responsible for early
life termination as a result of this explanation, all contracts are binding, the price of your shares
can go up as well as down, blah, blah, blah, yada, yada, yada.........

Next logical question would be, why am I choosing to fu*k with an ignition system that works
perfectly well.
And the answer is simple, or to be more accurate, simplify.
With the wasted spark set up shown above all you have is the coil, three wires running to it
from the ecu which power it up and trigger coil A or B, and then a few HT leads to carry
the high voltage down to the spark plugs. And thats it, thats the sub total of our new ignition system.
With the addition of one simple self contained wasted spark coil we've managed to dump the distributor,
the distributor cap and the rotor arm, all of which can be a source of frustrating ignition problems as they age.

And that, in a nutshell, is the reason for going the wasted spark route. No performance advantage, just plain
old reliability.

With all that said, it's almost certain now that this new coil will somehow manage to short out and set the car on fire
just to keep Murphy's Law alive and well.

More pic's, less bull. Here how it all got nailed together.

With the distributor deleted this left the small problem of a gaping hole in the end of the cam box.
Step forward one distributor blanking plate supplied by Massive (link to website earlier in thread)..........



And bolt it on to cover the hole where the distributor used to be........



There is one other slight change which can be noticed in the picture above
and thats the three little studs that used to hold on the distributor and now
hold on the cover plate. They've been replaced with slightly longer studs.
The reason being they've another job to do as well.
Cardboard template............



transferred to aluminium.........



weldy, weldy......



and bolt her up..........

[xworks]

^^ thanks for the heads up, much appreciated.

[avhbi]

This air feed is what keeps the engine breathing when the
throttles are shut and as it feeds all four cylinders I'm hoping that the vacuum in
this pipe should be smooth enough for the Map sensor to do it's thing.

Had this problem with an RB26 engine. All we did though was make a mini plenum i.e. stiff plastic box, that dampened down the pulses.

[Massimo]

Nice. I was expecting an Alpha N setup but, then you threw that curve ball in there.

Can't wait for the next episode. I excited like a little school girl. Curious as to weather you actually have the car running yet?

[samiam3356]

Impressive work

Sub'd

[xworks]

bit of hammering and liberal quantities of glue.........



and bingo.......



The next item on the list was one of the few sensors that survives from the old
set up, the water temperature sensor..........



Its job and the way it operates is pretty much identical to the air temp sensor.
Two pins on the sensor, 5 volts go in, depending on how hot or cold the water is
that the sensor probe is sitting in a percentage of that 5 volts makes it back up to the ecu.
Again the ecu needs to know how hot or cold the engine is so it can adjust the fuelling
and spark accordingly.
Sensor sits into it's usual place on the water rail (blue sensor) right beside it's neighbour next door
the little brown sensor, which has nothing to do with engine management but instead
just runs the water temp. gauge up on the dash..........



And finally on to the last of the main ecu inputs, the crankshaft sensor.
All of the sensors fitted up till now have dealt with sending
information to the ecu so it can calculate how much fuel to squirt into the
engine and when it needs to fire the spark. The next input is probably more
important than all of these, as the crankshaft sensor lets the ecu know 3 vital
bit's of information.
Firstly, that the engine is turning over.
It might sound simple but without the signal coming in from the crank sensor the
ecu has no idea the engine is turning over. If it doesn't receive this signal then
the party's over.
Secondly, ecu has to know how quickly the engine is spinning over so it can
figure out how long it has to open the injectors and squirt in the fuel, also
it needs to know when to send the spark. As the rev's start to rise
both the fuel and the spark need to be introduced sooner if that bang is
going to happen while it's still useful. So, second task for the crankshaft sensor
is to send back some info to the ecu and let it know how fast the engine is turning.
Third job, and equally important, is to let the ecu know exactly what position
the engine is at. Not much good the ecu squirting in fuel and lighting the spark
if the piston is only halfway up the cylinder and the resulting bang sends the piston
out through the block.

So, how does the crank sensor do it's business?
Well, the crank sensor is only one half of the solution, the other half being a toothed
wheel as seen below........



There's two main types of crank sensor a "VR" type and a "Hall" type.
The VR type generally uses two wire's and the Hall type use's three wires.
(I'm going to say I haven't got the time to explain the differences right now,
but we both know the truth is I'm guessing most of this stuff up till now, and I
know that little about these sensors I can't even bullshit my way of this one.)
The one thing thats worth mentioning before we move on is if your switching
over to an aftermarket ecu then it's likely the ecu your going to use will favour
one type or the other. Make sure you get the right one.

The sensor I'm using here is a VR type sensor (Variable Reluctance) and inside it
is a little magnet. Very basically, the sensor has two pins. When you send voltage
in one pin and pass a bit of metal in front of the sensor it does a bit of black magic
and dumps out a little pulse of electricity on the other pin.

So, how the hell does this help the ecu figure out anything?

Well, it we bolt the sensor on to the front of the engine pointing towards the
crankshaft pulley............



and then attach the little toothed wheel to the crankshaft pulley that will spin right in
front of the sensor.........





The sensor will "see" the teeth on the toothed wheel and send back a little pulse
of electricity to the ecu every time a tooth passes it. If the pulley has 36 teeth equally
spaced out on the wheel and we tell the ecu that a full turn of the engine is 36 teeth
then the ecu can now count the teeth/pulses and figure out how many rev's the engine is doing.

So now the ecu has a way of telling the engine is spinning over and figuring out what
speed it's running at, the final thing it needs to know is what position the crankshaft is
at so it can squirt and spark at the right time. The way this is done is by removing one
of the teeth on the toothed wheel, and if you look at that first picture above showing the
toothed wheel you'll see theres only 35 teeth and a gap where the 36th one should be.

Why the hell is there a missing tooth? Did you keep the receipt? Cancel the Paypal quick.

The reason one of the teeth is missing is so the ecu can figure out what position the engine is at.
When the toothed wheel is fitted to the crankshaft pulley we measure up when the next tooth
after the missing tooth will pass the crankshaft sensor.
In the case of this engine the next one after the missing tooth passes the sensor at 90 degrees before the
engine reaches top dead centre (TDC).
So we then tell the ecu when you spot the missing tooth/pulse the next tooth
you see is at 90 degress BTDC. With this knowledge the ecu can now figure out exactly what position
the engine is at because it knows theres 36 teeth equally spaced out (35 + 1 missing one) so each time it
reads a tooth pulse it knows the engine has rotated 10 degrees (360 degrees divided by 36 equals 10 degrees).
With these two bits of information the ecu can now pinpoint any degree it likes to inject the fuel and
fire the spark.

The toothed wheel you see in the pictures and the little bracket for holding the sensor were sourced
from here: http://www.massivebrakes.com/accessories.php
And the sensor I've used is a "Standard Pc 19" which can be found through a Google search.

(Probably worth mentioning at this stage that the standard S14 engine management uses
crankshaft sensors too, but it's an odd set up which uses two sensors to do the same
job described above and isn't compatible with a lot of aftermarket ecu's including mine,
hence the reason I've gone with the above.)

And a picture of the final setup on my engine.........



And that ladies and gentlemen brings us to the end of the first instalment of
this update. With all the main ecu inputs sorted next up we'll delve into
the coma inducing world of the ecu outputs, ignition coils and injectors.
Talk to you all again in a few years time.

Till then...........