EMS with Electric Dizzy

ImpulseRocket89
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EMS with Electric Dizzy

Post by ImpulseRocket89 »

I see a lot of guys talking about using the 4ZE1 optical/electronic distributor to run multiple coil ignitions, and I tried a search to find this info without too much luck. I did see one where the person custom made a 62-2 trigger wheel and looked like the hall sensor from the factory dizzy.

My question is, are they using this as a crank sensor, or to act as a cam sensor?

The reason I ask is, with the MS3 w/ MSX daughter card, I can run sequential EFI as well as Coil on Plug (LSX coils or similar) with it, but I fail to see how one could run the crank trigger wheels with the proximity of the 4zc1 crank pulley and the lower timing cover. Even a thinner wheel would be difficult to make work from what I see on my engine.

I have an extra 4zc1 optical dizzy sitting around here that I could easily do some modifications to and have it act as a sensor, but without the crank sensor I am still limited.

One of the best solutions I have found, but requires a bit of machine work and destroying the distributor to do it, is to run an AEM Engine Position Module. This unit is designed to give both crank and cam position readings (it uses two separate Hall sensors for each signal), and its 24 tooth cam and 1 position cam can be read and run by the megasquirt. http://www.aemelectronics.com/engine-po ... 8uq0g3qpd5

This is the internals of it.
http://sphotos-a.xx.fbcdn.net/hphotos-a ... 2995_n.jpg


IMHO at $166 for the universal, it's actually not a bad deal. granted with whatever machine work needs done that could easily double. On the upside, it would eliminate the need to seal it off with a distributor cap and reduce the profle considerably. This leaves more room for a completely custom intake manifold without issues of getting the cap off.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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Post by IZU069 »

The dizzy is a crank sensor. Or more importantly, it is a "cycle" or cam sensor which is what you want for sequential.
A mere crank sensor without smarts can only dual- or wasted-spark fire (ie, 1&4 together, then 2&3).


That puck sensor is a cam (angle) sensor - not crank (position) sensor.

Filling in 3 of the 4ZE1's 4 slots and all except every 15th slot in the 360 slot ring is exactly equivalent to that puck.

My choice would be 1 & 360 since that gives you a 2° crank position resolution. (Mine was based on the ~120 flywheel teeth hence a 3° crank resolution.)
The 1:24 "puck" is a 30° crank resolution.
Not that it matters much since the timing iterates between the position sensings, but as a possible fallback or limp home mode it could be handy. IE - if the CPU fails, a simple RPM comparator could advance one slot, ie, 2° etc.

There are various reasons why different timings (slot numbers & position) are chosen.
My own preference would be that the Ref slot (the 1 or 4) is at a compromise timing suitable for limp-home mode - ie, retarded enough to start, but advanced enough for a "reasonable" RPM to get home.
My choice is probably the single Ref slot with simple IC counter to fire the other 3 splugs (sequentially) should the main CPU fail. That would assume the other sensor still works (ie, the 360-slot sensor in the 4ZE1), but my last-millennium system assumed dual redundant pickups sensing the flywheel ring gear teeth. (If that failed, I''d carry a standard coil and refit the dizzy.)
If I had a only a single CPU circuit (no other "counter" fallback), I'd use 4 Ref slots (and fire all splugs simultaneously if it were wasted or sequential) at the compromise limp-home advance angle.

[ Incidentally, despite many apparently "laughing" at the idea that a normal distributor can do sequential ignition (& EFI), unfortunately I laugh louder as I can do it - as can a few others I know (yes, the laughing too!). I admit I was looking at a simple mod to a G-Z dizzy (ie, Gemini - whether points or with the RB Gemini reluctor conversion) and using a 4017 counter, but worried that the hall sensor chip's (UGN3503) temperature rating of +85°C wasn't enough, I fell back to the "add on smarts" method. But the smarts are a much easier fit anyhow (it's an add on - no need to add a sensor to the dizzy). Beside, the "smarts chip" only costs ~$4 (a PICAXE 08M2). ]

Back to Ref & Sync slots etc...
Otherwise I'd prefer the Ref(s) to be at (or a bit before) the maximum advance angle... (Like the old Lucas-RITA reluctor systems with the reluctor doing the advance spark.)



Hall sensors sounds a bit retarded. (Ooops, pun not intended.)
Are you sure it isn't a reluctor?

Reluctors are the go. Even the old Siemens HKZ-101 Hall Effect/Sensor systems (Bosch etc) seem to have given way to the reluctors.
The beauty with the reluctors is their robustness, and no temperature variations nor dependence on correct analog thresholds that Hall Effect (and optical) sensors have. Hence accuracy and reliability.


I'd use the 4ZE1 dizzy else its guts. And I'd buy a spare ($35 each from local wreckers) else know they are readily available.


And FYI, I think the 4ZE1 Jackaroo/Trooper dizzy is lower than the Rodeo version (they are different heights anyhow).
HOWEVER, with machining, the Rodeo may be lower because it has its 4x1 connector out the side (as opposed to the Piazza/Jackaroo's 2x2 connector down & out through the bottom).


Oh boy, what memories! [Not that I have coded for the PICAXE. My ignition was based on ancient 68HC11s! (Else a 6511.)]
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Post by ImpulseRocket89 »

Actually, that puck is both a Cam AND a Crank sensor. Read the tech on it. :yawinkle:

It contains two Optical sensors. The ring itself contains multiple small slot holes that are picked up and translated by the internal processor. This processor counts and decodes the signal, and from some overly complicated explanation in the information sent to me by AEM, it sends the signal as a 24 tooth crank position sensor. One of the holes is longer, and this is picked up by the second optical sensor only. This long hole is the crank position sensor.

Everything else you said I am trying to decipher. I understand what you are saying about resolution etc, but 24 tooth crank triggers have been used on numerous factory engines (LS2 and Toyota V8's(either 24 or 48 depending in generation). A good CPU processor and programming is the key.

What I can't figure out is what you said you used for crank position signal. Trigger wheel? Flywheel teeth? I am at a loss.
Last edited by ImpulseRocket89 on Wed Aug 22, 2012 6:59 am, edited 1 time in total.
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Post by IZU069 »

Yes, but for sequential ignition, it must be used off the cam. (Which using the dizzy position is usually easier to fit.)
On the crank it will only do wasted spark.

(Unless you have external smarts in which case there are several alternaives.)
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Post by ImpulseRocket89 »

IZU069 wrote:Yes, but for sequential ignition, it must be used off the cam. (Which using the dizzy position is usually easier to fit.)
On the crank it will only do wasted spark.

(Unless you have external smarts in which case there are several alternaives.)
It supports both at the same time. With that puck and the MS3 w/ MS3X card it will do both sequential injection AND COP ignition.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"
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Post by ImpulseRocket89 »

You gotta understand, I know the tech behind all of this. That wasn't my question.

My question was the use of said opticals, and how people were getting crank signals on these engines.

Not about the tech or tuning ideas themselves, as that part I am familiar with. This is not my first Megasquirt build/use.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

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Post by IZU069 »

For a REF pulse using the 4ZE1, block off 3 of the 4 slots.
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Post by ImpulseRocket89 »

IZU069 wrote:For a REF pulse using the 4ZE1, block off 3 of the 4 slots.
Ok, so essentially turning it into a 1 hole cam sensor.

What do guys use for crank signal then?
1988 Isuzu Impulse Turbo.
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Post by IZU069 »

Why do you want a crank signal?

If you want to duplicate that puck as a crank sensor but using the 4ZE1 dizzy in the dizzy location, just blank off 2 opposing slots in the 4-slot ring.

Do what you want with the 360 slots - ie, 24 cam slots as per the puck; though unfortunately not the 48 slots of the puck as a crank sensor - unless you use +ve & -ve edge triggering (which is fine since the mark-space ratio of the 360 slots id 1:1).

That's the beauty with using 360 slots - it can be subdivided by 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120, 180.


PS - we are talking sequential (spark or injection) right?
For that a crank sensor is useless as it cannot tell which stroke is acting (ie, TDC compression or exhaust).
Hence the cam sensor. (Unless the ECU (or PIC 08M2!) has smarts.)
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Post by ImpulseRocket89 »

I need both cam and crank to run sequential fuel and coil on plug (or any EDIS style) ignition and have decent resolution. The Megasquirt CAN run sequential COP and Sequential EFI with a missing tooth cam gear, but it's not recommended. Having both inputs is ideal.

In the chart on the top part of this page http://www.msextra.com/doc/ms3/trigger-wheel.html The mode I would be running is the 7th one down. "Non-missing tooth cam wheel with single-tooth cam"
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Post by IZU069 »

You cannot run sequential off a crank sensor (without smarts).

You have the cam sensor.

I fail to see why a crank sensor is also needed. The cam sensor has that PLUS the cycle info. (Unless you cannot reconfigure the crank angle, but I doubt that to be the case.)


With the 4ZE1 dizzy you have 2 degrees crank resolution in standard mode.
Modified for edge trigger means 1 degree crank resolution.

But neither should be needed as the ECU does the required interpolation. If not, that puck only provides 15 degree crank resolution, or 30 degree crank resolution if used on the cam. Both are too large for meaningful spark etc advance or retard.

And as I wrote, you have all those Megasquirt trigger-wheel resolutions on the 4ZE1,
Some systems only use 4 pulses per cam revolution (2 per crank rev).
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Post by ImpulseRocket89 »

You are right, I don't need the crank signal, no matter where it is driven from. I just recall talking to another person that tried it that way and he said if I had the option to go with a crank and cam signal. I don't recall exactly what he stated the reasons were, but he went from just a crank to crank and cam signal and said it was night and day.
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Post by IZU069 »

There are lots of people with seemingly knowledgeable information...

But yes, with a cam signal, the crank is redundant.
In fact I'm trying to think of an OEM engine with crank sensing. Not that I am "expert", but all sensors I have seen are cam driven. And certainly all for sequential.

I do know of aftermarket ECUs that use crank sensing, but they are wasted spark and injection.
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Post by ImpulseRocket89 »

IZU069 wrote:There are lots of people with seemingly knowledgeable information...

But yes, with a cam signal, the crank is redundant.
In fact I'm trying to think of an OEM engine with crank sensing. Not that I am "expert", but all sensors I have seen are cam driven. And certainly all for sequential.

I do know of aftermarket ECUs that use crank sensing, but they are wasted spark and injection.
I trust his advice. He has built, installed, and tuned quite a few megasquirts on his own, and other peoples vehicles.

Factory cars that use crank signals. I would list them, but that would make this a long post. The crank signal in most factory application is utilized for timing with the ECU as well as Cam sensors, but you are right that most of the fuel/spark stuff is done with the cam sensor.

The problem with Cam sensing comes from harmonic issues that can throw off signal, but also timing belt/chain stretch that can throw it off a bit. Generally not a huge deal, but does exist.

In all honesty I will probably just modify the stock cam for a 1 "tooth" pickup, and do a 62-2 crank trigger wheel. Yes, not needed, but not expensive or difficult to pull off. I will just have to front mount it to the crank pulley. Luckily there is a company that will center bore and drill mount holes for hex bolts to mount directly to the crank pulley face, all done by CNC, for not a bad price.
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Post by IZU069 »

Agreed with the cam slack etc and hence the desire for a crank sensor, though I don;t think that's a big issue. Besides which an ECU should be able to compensate, but that's with a bit of self tuning (which seems to be beyond the capabilities of many).

I'd be running my aforementioned crank system since that can be used on any Isuzu engine (I have the OHVs else the DOHCs), and my ECU would figure out the sequential. Hence sequential with "absolute" accuracy.


But I do view crank & cam sensing as being outdated. Last time I looked, I would have gone the way of ionic sensing, but I don't know how far that has progressed. (If people still think Haltec is good because of its vast number of maps, I suspect little advancement.)

Even with crank AND cam sensing, if the ECU is not able to tune (ie, learn or or self tune), I see little advantage. The natural "drift" of combustion conditions has IMO way more (detrimental) effect than slop of delay in the cam.
Same too for O2 sensing systems.
Compare that to ionic which can vary the mixture and ignition timing for each individual cylinder for optimum economy or power etc.


I don't understand the harmonics issue. It's not like its mixing analog signals or digitally sampling an analog signal (ie, aliasing etc), and the each pulse is what it is - a timing pulse. And any timebase shifting due to variation of any cam delay should be be tracked, not absolute (ie, a limited slew rate), even though cam jitter shouldn't matter...

Oh sorry - my engines use chains, not stretchy belts.
Maybe that does warrant a cam sensor...
Else ionic sensing...
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