Where does TPS, CPS, etc get their power?

[Jon K]

Are the Crank Position Sensor and Throttle Position Sensor getting their power from the ECU? Would really like to know.

[Kalevera]

In the case of the hall effect/MR sensors, whacky semiconductors that switch flow, absolutely. Hence why they only need two wires. But my understanding of it is that they aren't really "getting power" -- they don't attenuate a signal. Maybe Steve can explain.

best, whit

[fujioko]

The crank and cam pickups are inductive and generate a small a/c signal. Looking at the Bentley you can see that both pickups are shielded to prevent false signals and crossover. Bentley also indicates that the signal is VAC pulse (voltage alternating current).
If they were hall effect then there would most likely be three wires with five volts present on one of the wires.

I feel honored that I answered a question for JonK.

[bjl4776]

The CPS is a magnetic pulse generator. Which does exactly that, generate ac voltage via induction. It produces a small voltage that increases in voltage and frequency as engine speed increases. The three wires that come from the sensor are ground, signal, and shield. The ECU uses the frequency to calculate RPM. The TPS is a potentiometer which means it has varying resistance depending on position of the throttle. The wires are power, ground, and signal. The Ecu generally sees .55v at idle and a full 5v at WOT.

[Javier]

Oxygen is special and has a heating element powered externally.

Javier

[Jon K]

The reason I ask is because I built this

http://e34.digital7.com/MegaSquirt/6cop4.jpg

6 Coil on Plug ignition control for MegaSquirt - just trying to figure out what minimal sensors I can run the car on

[Javier]

Javier

[Jon K]

Ignition control - full standalone ECU that will replace Bosch Motronic.

[fujioko]

I saved the picture and zoomed in on the TO220 devices. Best as I can tell they are ST devices. I assume they are IGT’s Looks like you have the gates already wired. Dose your MegaSquirt have provisions for multi coil ignition?

You probably already know this, but all you would need to do is buffer the CST signal and boost it by perhaps a gain of 10. Add a Zener to chop the wave at 5 volts. Same with the TPS signal. That’s assuming the MS has the ability to use both signals and calculate the proper timing. Otherwise I believe they also have a stand alone ignition module.

Home brewed fuel injection is so fun!

[Javier]

Javier

[Jon K]

I saved the picture and zoomed in on the TO220 devices. Best as I can tell they are ST devices. I assume they are IGT’s Looks like you have the gates already wired. Dose your MegaSquirt have provisions for multi coil ignition?

You probably already know this, but all you would need to do is buffer the CST signal and boost it by perhaps a gain of 10. Add a Zener to chop the wave at 5 volts. Same with the TPS signal. That’s assuming the MS has the ability to use both signals and calculate the proper timing. Otherwise I believe they also have a stand alone ignition module.

Home brewed fuel injection is so fun!


Fujioko - this is the provision for the coil drivers, these are the completed circuits. All I have left is to ground the middle post on each VB921 driver to MS ground and then from the third leg of VB921 out to the coil pack trigger. You are right, these are ST VB921ZVFI.

I just realized that the MegaSquirt harness has a +5v REF signal for the TPS... I kind of forgot that. So, it will provide the 5v out, I remember wiring in a Zener on it.

The unit can handle up to 6 coil sequential ignition, or up to 12 cylinder wasted spark igintion.

I am going to run 6 cylinder wasted spark coil on plug igintion.

[Jon K]

Javier - the unit by default runs the injectors, high or low impedence in two batch firing... so you have 2 sets of 3 injectors that you group alterating the firing sequence so it actually turns out to be 1 3 2 and 5 4 6 grouped together.

[t_marat]

Really, not understanding a heck of what you are talking about.. :)

[joshua43214]

Do you know any one that uses these coils as a waste spark system? waste spark coils are designed totaly different than single DI coils. Manufacturers only use waste spark because it is cheaper to manufactur then hand you a line that it is better since it fires on exhaust stroke. Waste spark plugs are also different in design since the spark jumps the opposite direction and will ruin conventional plugs very rapidly.

The more I think about it, the more I think it is impossible to use your coils as a waste spark. I suspect this is a misunderstanding of the application of waste spark systems.

[Jon K]

Joshua - people are running a TON of coils in wasted spark. I don't see how running wasted spark or not matters. The plugs will spark regardless, I don't understand what you mean different direction, it goes electrode to post.

I just talked to BJL4776 - technically I am not running "wasted spark" I am just firing two coils at the same time. I didn't realize "wasted spark" meant that the plugs use the cyl head or something to complete circuit and back up the coil. This is not what we're doing - we're just firing 2 coils same time, one while its on compression one while on exhaust stroke.

[MSM]

Hi Jon,

Re "I didn't realize "wasted spark" meant that the plugs use the cyl head or something to complete circuit and back up the coil. This is not what we're doing - we're just firing 2 coils same time, one while its on compression one while on exhaust stroke."

Wasted spark would apply to a system that fires the plugs twice in a cycle, first time near end of compression stroke, second time, the "wasted" spark, on the exhaust stroke. The system is used as it simplifys and reduces costs of engine management and ignition systems... you need half as many ignition drives and coils as you would if you were to run fully sequential ignition control. It's similar to the economy of complexity offered by batch fire injection systems, such as the motronic 1.3 on the m30 motors. :)

You could run wasted spark on an inline 6 using three coil units, each one driving two plugs.

FWIW: I have yet to see a spark ignition system that doesn't work by using the spark plug to cylinder head interface as part of the ignition circuit.

MSM

[Jon K]

Hi Jon,

Re "I didn't realize "wasted spark" meant that the plugs use the cyl head or something to complete circuit and back up the coil. This is not what we're doing - we're just firing 2 coils same time, one while its on compression one while on exhaust stroke."

Wasted spark would apply to a system that fires the plugs twice in a cycle, first time near end of compression stroke, second time, the "wasted" spark, on the exhaust stroke. The system is used as it simplifys and reduces costs of engine management and ignition systems... you need half as many ignition drives and coils as you would if you were to run fully sequential ignition control. It's similar to the economy of complexity offered by batch fire injection systems, such as the motronic 1.3 on the m30 motors. :)

You could run wasted spark on an inline 6 using three coil units, each one driving two plugs.

FWIW: I have yet to see a spark ignition system that doesn't work by using the spark plug to cylinder head interface as part of the ignition circuit.

MSM

Brandyn can explain the difference but Joshuas point was that the OEM coils fire "one way" and cannot be fired "the other way".

[bjl4776]

The waste spark uses one coil to fire two cylinders. What we are trying to do is to use one ignition driver to drive two seperate coils. So what will be happening is the coil on companion cylinders will fire at the same time. I.E. cylinder 1 and 6 will fire on both compression and exhaust but they both fire normally. A wastespark setup fires two cylinders the same way, but uses a single coil to do so. The spark travels from the coil, down the wire, crosses the gap on one cylinder, through the head to the other cylinder, crosses the gap and back up to the coil. Since a cylinder is on compression it has more compression and higher resistance in the plug gap and sends a majority of its power to the cylinder on compression. WE ARE NOT RUNNING WASTE SPARK. We are simplifying the ecu so we only have to tune 3 coils instead of six. Our ignition system is still COP, we are just modifying the means of controlling it by making it simpler for us.

[Jon K]

I just want to reword Brandyn. We aren't using one igintion driver to two coils, we're using 1 spark output signal to two ignition drivers, to two coils. So basically instead of having 6 spark outputs, 6 drivers, 6 coils, and 6 spark plugs, we have 3 spark outputs, 6 drivers, 6 coils, and 6 spark plugs. Basically putting a "Y" splitter on each spark output causing two coils to fire at every one spark event.

In addition to it simplifying the ECU design, it also allows us to utilize only one input sensor - the CRANK position sensor. In order to do sequential ignition (6 signals, 6 drivers, 6 coils, 6 plugs..) we need a "2nd Trigger" input. This means the ECU references not only RPM from the CRANK position sensor but also compares it to the CAMSHAFT sensor, that way the ECU can determine whether or not cylinder #1 is compressing or if #6 is compressings, since they'll both be BTDC at the same time - the difference is wasted spark COP doesn't care because sparks both and one is going to catch, the one with compression. I haven't even investigated 2nd Trigger input yet, maybe I will do sequential injection next. But truthfully, I am only running one Wideband sensor - in order to make use out of retard/advance per cylinder, you'd realistically need an EGT or Wideband per cylinder... and that's just ridiculous for a street car.

[Javier]

don't do god when spark current is reversed. Depending on the materials of the center electrode and the body, erosion can be higher if the current flow at the spark is reversed. Single coil wasted spark systems fire one plug with one current flow direction and the other with the oposite current flow direction.

Understand that M50 uses six coils, so shouldn't be the case if you are just trigering both coils together?

Javier

[bjl4776]

Exactly

[fujioko]

Jon K.
Figured you would be slightly interested in knowing this. I built a MS ver 2.2 for use on my Spitfire. I’m using a Subaru TBI for fueling the engine. I have collected all the parts and will do the install someday soon. For ignition I’m using a Dodge Neon coil pack and a modified distributor. Basically the distributor is outfitted with two pickups to trigger the coils …. a true wasted spark method. My ignition is very simplified by utilizing the mechanical advance and vacuum retard already incorporated in the distributor. No actual secondary voltage is transferred by the distributor.. I just use the distributor to keep the timing on par without resorting to a bunch of electronics (yet).

Anyway, since the Triumph engine was built with serious compromises I cannot extract more than 100hp without seriously jeopardizing the reliability. I guess the main fault is the engine only has three main bearings.. not the typical five as found in most four cylinders.

The truth is that 100 hp on a 1400 lbs car is plenty…. Especially since the brakes don’t really stop the car all that well anyway… yet another project.. but this is a BMW forum not a Triumph forum.

[Jon K]

don't do god when spark current is reversed. Depending on the materials of the center electrode and the body, erosion can be higher if the current flow at the spark is reversed. Single coil wasted spark systems fire one plug with one current flow direction and the other with the oposite current flow direction.

Understand that M50 uses six coils, so shouldn't be the case if you are just trigering both coils together?

Javier


Exactly - current flow is the same as stock, just two coils fire per igintion event.

[Jon K]

Jon K.
Figured you would be slightly interested in knowing this. I built a MS ver 2.2 for use on my Spitfire. I’m using a Subaru TBI for fueling the engine. I have collected all the parts and will do the install someday soon. For ignition I’m using a Dodge Neon coil pack and a modified distributor. Basically the distributor is outfitted with two pickups to trigger the coils …. a true wasted spark method. My ignition is very simplified by utilizing the mechanical advance and vacuum retard already incorporated in the distributor. No actual secondary voltage is transferred by the distributor.. I just use the distributor to keep the timing on par without resorting to a bunch of electronics (yet).

Anyway, since the Triumph engine was built with serious compromises I cannot extract more than 100hp without seriously jeopardizing the reliability. I guess the main fault is the engine only has three main bearings.. not the typical five as found in most four cylinders.

The truth is that 100 hp on a 1400 lbs car is plenty…. Especially since the brakes don’t really stop the car all that well anyway… yet another project.. but this is a BMW forum not a Triumph forum.


Yeah sounds like you have more of a mechanical wall blocking you than a logical/electrical. I hope it isn't too earlier to say that I think I've overcome the "technological challenge" in our cars. I am proud to say that I have the ground wires all hooked up and took the meter to it and everything is working as it should without throwing errors! Quite a feet considering no one has done this and no one could really provide guidance. I answered a bunch of questions I had myself, and Brandyn and I are probably the only M50 owners even thinking about this.

I set the spark output to inverted, dwell time to 3.0ms for now, and hooked it up to the Stimulator (pseudo engine emulator) and it runs great! Here are pics for all those who think wiring isn't confusing:

http://e34.digital7.com/MegaSquirt/6cop7.jpg

Fujioko - you should get a V3.0 board. Lot of advancement since the 2.2's. Much "easier" to use outputs and incorporates built in ignition controller for one coil. I just built a unit for JJDickm on this forum for his M30. Though it sounds like you're more concerned with your motors build quality.

[Booster]

I really hope this works killer in your cars guys. I want one like this for my turbo M50 when you get the time Jon. I think this will bring performance and tuning for these cars into a higher level of self maintenance. Who needs the factory claim if something else runs better ? Not me.
I'm sure Jon and Brandyn don't need to be told this though.
Hmmm.........I wonder how long a stock M50 will live with this MS and light boost ?That is before it requires a rebuild and all of the other basic upgrades.....headstuds,HG, etc.
................V':D

[bjl4776]

The complexity of the stock OBD-1 is not overwhelming. Since i am going to school for automotive it makes it a little easier, but even with the megasquirt it is just as simple. The only thing that makes any difference between MS and ODB-1 is most emissions related. The support for these is amazing, but like Jon said we are trying something nobody has with these yet. But even though it has never been done before, if you no your electronic principles it isnt hard. I had a problem with my board, and using tests that i know such as voltage drop, avaliable voltage, diode tests, I was able to diagnosis my problem, wich was a burnt board, and fix it by making the circuit externally.