Stand-alone ECU

Thanks Paul, I'm looking forward to it.

A couple of companies (AEM being one) are making distributor located trigger units for standalone ECU's. Basically the top half of a stock distributor is cut off and a custom designed 'head' replaces it. The head has trigger wheels and sensors to offer the input signals. One representative used the following statement to describe it's advantage to using the stock hall-effect trigger in the stock distributor: "it replaces a analog sensor with a digital one". Frankly that statement does not make sense to me, I think it was marketing hype. But maybe the advantage of building this type set-up is what you said about hall-sensors needing some width on the trigger? And/or perhaps the two wheels/sensors located there are a big advantage (although I'm not clear why 2 are needed from the same drive source)?
Edit: It occurred to me the advantage to this over the stock hall trigger in the distributor might be that the new wheels have a greater number of teeth (compared to the 4 on the stock ignition), for greater precision?

Here is the one from AEM: http://www.aemelectronics.com/?q=products/ignition-components/engine-position-module-epm
 
TonyK, I was forgetting you are only using the 500 engine as a swap. That would be a different picture. The company is based in Poland (hence the language issues) but they have a full-support facility (direct importer and US distributor) in Texas. You might be better off communicating with the Texas location (very knowledgeable guy).[/QUOTE]

The information supplied will not support the Multi Air engine. If the vendor does not have it I don't think anyone else does.

TonyK.
 
Bringing up this earlier thread to ask another question about aftermarket ECU's.

I've been doing some reading and one thing that keeps coming up is the use of two trigger sensors, one on the crank and another on the cam. But none of the info explains why two are needed. Is is just a redundancy factor to double check the timing (i.e. increased accuracy), or is the cam sensor used for a completely separate function?
 
Dr.Jeff said:
Bringing up this earlier thread to ask another question about aftermarket ECU's.

I've been doing some reading and one thing that keeps coming up is the use of two trigger sensors, one on the crank and another on the cam. But none of the info explains why two are needed. Is is just a redundancy factor to double check the timing (i.e. increased accuracy), or is the cam sensor used for a completely separate function?
Click to expand...

I would have to think that with current engines being able to dynamically change cam timing in relation to where the crank is, you would need a sensor for each rotating item. On older engines like the SOHC, cam and crank rotation are locked together so if you know where one is, you automatically know where the other one is (putting aside aftermarket stuff like adjustable cam wheels).
 
Dr.Jeff said:
Bringing up this earlier thread to ask another question about aftermarket ECU's.

I've been doing some reading and one thing that keeps coming up is the use of two trigger sensors, one on the crank and another on the cam. But none of the info explains why two are needed. Is is just a redundancy factor to double check the timing (i.e. increased accuracy), or is the cam sensor used for a completely separate function?
Click to expand...


Crank position sensor tells the ECU where the crank is at. It will tell the ECU that you're at TDC, but it won't know if you're at TDC on the intake stroke or the power stroke. That's where the cam position sensor steps in. It tells the ECU which stroke the engine is at for a given cylinder. It isn't about variable valve timing in this case.

That said, Hall effect sensors are excellent choices for crank position sensors. They're incredibly common in this application.

Finally, a cam position sensor is NOT required by all ECUs and configurations. Many ECUs support batch fire configuration where the injector fires irrespective of whether the intake valve is open or not. Batch fire of injectors works just fine. If you want sequential injection, then you'll absolutely need a cam position sensor to tell the ECU when your valve is open (or about to open) in order to fire the injector just in time.
 
Ahhh, I get it, thanks Mezz. I was thinking along the same lines as Dan, with cam position relative to vario-cam changes. But the cam sensors are used on engines without vario-cams.

Are there other factors that would influence the choice of batch fire vs sequential fire; maybe like the design of the injection system, or type of injectors, or the ignition system, or ???
 
Mezzanine said:
Crank position sensor tells the ECU where the crank is at. It will tell the ECU that you're at TDC, but it won't know if you're at TDC on the intake stroke or the power stroke. That's where the cam position sensor steps in. It tells the ECU which stroke the engine is at for a given cylinder. It isn't about variable valve timing in this case.

That said, Hall effect sensors are excellent choices for crank position sensors. They're incredibly common in this application.

Finally, a cam position sensor is NOT required by all ECUs and configurations. Many ECUs support batch fire configuration where the injector fires irrespective of whether the intake valve is open or not. Batch fire of injectors works just fine. If you want sequential injection, then you'll absolutely need a cam position sensor to tell the ECU when your valve is open (or about to open) in order to fire the injector just in time.
Click to expand...

Ahhh, so it's not so much for ignition, it's much more for the type of FI you have (batch or sequential).
 
Mezzanine said:
That said, Hall effect sensors are excellent choices for crank position sensors. They're incredibly common in this application.
Click to expand...

Are you sure about that? Bosch for example doesn't use Hall Effect, and I don't think most OEM systems do either. Can't recall the name of the (inductive?) style used with most Motoronic, etc.. Unless I'm misreading, I thought hall effect described the old style wound core units as used for igintion systems up through the early 80's for the most part.
 
Simon Oaten said:
spark is waaaaay more important
Click to expand...
So is the crank trigger (which as I understand it, is the ignition's main signal source) waaaaay more important than the cam trigger (which I believe is primarily the fuel's main signal source)? Therefore, what "Mezz" said:
Mezzanine said:
Finally, a cam position sensor is NOT required by all ECUs and configurations. Many ECUs support batch fire configuration where the injector fires irrespective of whether the intake valve is open or not. Batch fire of injectors works just fine. If you want sequential injection, then you'll absolutely need a cam position sensor to tell the ECU when your valve is open (or about to open) in order to fire the injector just in time.
Click to expand...

lookforjoe said:
I thought hall effect described the old style wound core units
Click to expand...
I think "hall effect" simply refers to a magnetic pulse (inductive) type trigger? Which I believe is what most of the OEM systems use...but I'm not sure. As opposed to say a optical (light) trigger? Or is there more to it than that?
 
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Dr.Jeff said:
So is the crank trigger (which as I understand it, is the ignition's main signal source) waaaaay more important than the cam trigger (which I believe is primarily the fuel's main signal source)? Therefore, what "Mezz" said:



I think "hall effect" simply refers to a magnetic pulse (inductive) type trigger? Which I believe is what most of the OEM systems use...but I'm not sure. As opposed to say a optical (light) trigger? Or is there more to it than that?
Click to expand...

No, Hall effect does describe a specific type of inductor/field generator. It would be with the winding around the unit. A Hall switch is something else - that is what is used for older Bosch cam sensor signalling & distributors (Ignition used with LH2.2, Motronic 4.4, ME7 for example)

Editing for clarity - my misunderstanding based on Volvo / Bosch design & function manuals. They used Hall Effect to describe VR, hence mine confusion when Hall effect was used to describe the later crank position / cam position sensors.
 
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That makes sense because the X's dizzy is not referred to as "Hall Effect", but a "Variable Reluctor Inductive Pickup". Although I'm not certain exactly what that is, it is magnetic.
 
The two types of trigger sensors commonly used are VR and Hall. VR is variable reluctance, and is a magnetic pickup. And yes, I'm quite certain that hall sensors are very common in crank position sensors. Here's the first article google provided me when I searched "hall vs VR crank position": http://fullfunctioneng.com/info/Hall vs VR.pdf
I've configured engines on hall sensors a number of times, and I've often used OEM parts to do so.

The Crank position sensor is driving the ignition events. Generally speaking, if you have a configuration WITHOUT a cam position sensor, you'd be running a wasted spark system as well. Since the ECU wouldn't know which stroke the engine is on, it would fire the spark at whatever BTDC the map tells it to on every rotation.

Dr. Jeff, to answer your question about choosing batch fire vs. sequential injection: there are many factors that could influence that decision. Sequential allows for more individual cylinder tuning control, and *can* yield better low-air speed (idle, low rpm) performance. There isn't a "this is better than that" clear line here. As with everything, it depends on what your goals are. I'm going to be sequential on the hot little 1300 I'm building because it's going to be inducted on ITBs and I can use all the idle/low speed/transition help I can get.
 
I realized I should add another point of clarification: running a cam position sensor is required for sequential injection, but it doesn't mean that's the only reason you'd want to run one. Spark timing would naturally be another reason. So you could run a single spark event on the compression stroke instead of wasted spark like I mentioned above.
 
Jeff,

ignition timing is more important - the type of trigger / output - basically determines the "lag time".....a trigger system is also used to work out "rate of change" - so the "more teeth = better" .....GM also use this to work out abnormal combustion (60-62 teeth) - again there are lots of ex sae papers on this....

there are lots of excellent SAE papers on torque vs optimised ign timing ......the % diff in Tq over the tuning range can often be 10-15% ........the diff in Tq for chg in Lambda is like 4-5% over the tuning range (say 0.82 - 0.92).

this means that working out the knock limit for your setup is more significant to output than fueling (obviously one has to have sufficenet capacity in fuel system) - so imho - either find an ecu that can do good knock control, and find a guru that will assist in mapping (understanding that you have to create a knock events so that you can log the response - to calibrate the system....you then need to make it "safe" by mapping the compensations (air_temp, water_temp, man_press etc etc).
 
Mezzanine said:
I realized I should add another point of clarification: running a cam position sensor is required for sequential injection, but it doesn't mean that's the only reason you'd want to run one. Spark timing would naturally be another reason. So you could run a single spark event on the compression stroke instead of wasted spark like I mentioned above.
Click to expand...

I assume that it's important for sequential injection so that the injector pulses when the intake valve is open? That's what I've always heard.

However, here's what confuses me about that. Most engine management programs run the injector duty cycle fairly high - up around 80-90% at max flow, don't they? But the intake valve is only open for maybe 30% of the time, so it seems like trying to match those two up is mostly pointless.

Not trying to argue with anyone, just want to learn something.

Pete
 
Pete Whitstone said:
I assume that it's important for sequential injection so that the injector pulses when the intake valve is open? That's what I've always heard.

However, here's what confuses me about that. Most engine management programs run the injector duty cycle fairly high - up around 80-90% at max flow, don't they? But the intake valve is only open for maybe 30% of the time, so it seems like trying to match those two up is mostly pointless.

Not trying to argue with anyone, just want to learn something.

Pete
Click to expand...

Excellent question Pete. You've gotten right to the crux of sequential injection. Sequential systems have FAR less time to fire the injector for a given volume of fuel, and as such, they need to be a much larger/higher flow rate. You'll run a larger injector on a sequential system than you would in a batch fire system. In my somewhat limited experience with sequential injection, you're really only truly running sequential injection at lower engine speeds. At higher speeds you're firing the injector earlier and longer to account for the reduced time the valve is open and reduced time between opening events...which means you aren't truly sequential at that point anyway.

Simon is offering really solid advice about timing and knock- we get our power from ignition timing and that requires a great deal of care in getting it close without actually creating a knock event. The selection of ECUs that handle knock is still somewhat limited, but there are independent systems (e.g. Plex Knock Monitor) that can help you set up a map. Many tuners include knock detection as part of their dyno tuning process.
 
Mezz and Simon, thank you both for the excellent information. I've done a lot of work with mechanical injection (eg. Bosch CIS), but not too much with electronic beyond typical diagnostics/service. So this is part of my learning curve as I plan a system around an aftermarket ECU.

Another question. I see several options for adding the trigger wheel/sensor to the front crank pulley, but not so much for the cam pulley. On a old school engine like the X's, that has neither provision, how is a cam position sensor typically added?

Just an observation: So far the ECU's I've looked at (within my budget), some offer better options in one area while others in another area. Kind of trade-offs with none having a great mix of all the good stuff. Most can add other features that aren't included but that raises the complexity (and cost).
 
Adding a cam position sensor doesn't have to be particularly tricky. You can use the distributor as the CPS since it turns at the same speed as the cam. The trigger wheel for a cam sensor need only have ONE tooth since all it has to do is tell the ECU when a particular cylinder is on it's compression stroke. So you could also make a pretty simple flag on your cam sprocket that is read by the sensor of your choice. Also note that the Lampredi engine came with a cam driven distributor in later iterations - adapting a sensor to that assembly would also be a good option. Irrespective of the location you choose, some fabrication will be required.

Finally, your comments on ECUs reminded me to offer this piece of advice: SOFTWARE. Download the software for the ECUs you're considering (it's usually free). There are plenty of ECUs out there that offer a great list of features, but have a lousy interface to tune with. Are you going to hire a tuner? See what they're familiar with. You'll save a lot of money in tuning time if they're able to get right to work tuning your engine instead of spending your tuning time learning the software. If you're tuning yourself, spend time getting comfortable with the software.

It's a slippery slope to look at ECU features - most of the time even the most basic ECU does all the things we need. Care to share your budget and what features you're looking for?
 
jeff,

search punto turbo phase sensor

also well worthwhile reading throu the megasquirt manuals, and then asking yourself "what do I want the puter to control" .......and then carefully chk what box will work with "available senors", and then go throu the important things like logging / sample rates / update rates / resolution etc etc .....

concur with Mezz - take the time to download softwares - and see ease of use, and chk the "data analysis" software at same time! - some are clunky, some are easier to use.
 
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