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C.O.P. for L67? by conan469
Started on: 01-16-2014 03:44 PM
Replies: 128 (2932 views)
Last post by: ericjon262 on 03-02-2014 01:17 PM
carbon
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Report this Post01-28-2014 04:53 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
A howto for Megasquirt and direct coil control with the 3500(LX9) coil pack.

Direct Coil Control
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Report this Post01-28-2014 04:56 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
interesting, thanks!
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Report this Post01-28-2014 05:09 PM Click Here to See the Profile for conan469Click Here to visit conan469's HomePageClick Here to Email conan469Send a Private Message to conan469Edit/Delete MessageReply w/QuoteDirect Link to This Post
i have those schematics too, but it doesn't say anywhere what the IC signal is.
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Report this Post01-28-2014 05:21 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by conan469:

i have those schematics too, but it doesn't say anywhere what the IC signal is.


no it doesn't, and that's not really the reason I posted them. I posted them because it shows the LX5 uses a single(larger) module and 3 coils (per bank) whereas the LSx engines use a coil with an integrated module. so each LSx coil may be able to interpret the PCM signal just fine. it just depends on exactly what the ICM's are looking for.
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Report this Post01-28-2014 05:57 PM Click Here to See the Profile for conan469Click Here to visit conan469's HomePageClick Here to Email conan469Send a Private Message to conan469Edit/Delete MessageReply w/QuoteDirect Link to This Post
i know, and with the way gm usually does things i would bet the LX5 ecm uses the same +5v the LS ecm does.
but i can't prove it yet. if i see a LX5 i'll test it.
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Report this Post01-28-2014 05:58 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by conan469:

i know, and with the way gm usually does things i would bet the LX5 ecm uses the same +5v the LS ecm does.
but i can't prove it yet. if i see a LX5 i'll test it.


my thoughts exactly.
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Report this Post01-28-2014 09:11 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
LOGIC CONTROL guys holy crap I posted it on the first page!!!!!

 
quote

The LS2 built in coil igniters (the amplifier that drives the coil's primary current based on the sequencer signal) will follow the sequencer signal pulse width. When the signal from the sequencer is high (3 to 5+ Volts - with very little current from the controller, a few dozen milliAmps), the coil current will be building. When the signal from the sequencer is pulled low (shut off), the coil will spark. The duration of the signal from the sequencer determines the dwell (though the coil igniter limits this to no more than ~8 milliseconds).


http://www.megamanual.com/seq/coils.htm
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Report this Post01-28-2014 09:42 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:

LOGIC CONTROL guys holy crap I posted it on the first page!!!!!


http://www.megamanual.com/seq/coils.htm



? did I say anywhere that you were wrong? the ignitor still has to receive a signal from the PCM to work, and this signal very well could be the same between the two.

thank you for the link though, lots of cool info in there.

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Report this Post01-28-2014 11:15 PM Click Here to See the Profile for conan469Click Here to visit conan469's HomePageClick Here to Email conan469Send a Private Message to conan469Edit/Delete MessageReply w/QuoteDirect Link to This Post
The point behind our last few posts is - what logic signal does the LX5 ecm output to the coils?
We know the LS is 3 - 5v. But it is not documented if the LX5 is the same.
I think they will be the same since they are both called logic drivers.

[This message has been edited by conan469 (edited 01-28-2014).]

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Report this Post01-29-2014 10:19 AM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by conan469:

The point behind our last few posts is - what logic signal does the LX5 ecm output to the coils?
We know the LS is 3 - 5v. But it is not documented if the LX5 is the same.
I think they will be the same since they are both called logic drivers.



You pull the 5 volts to ground, aka logic wave. You will run the coil inverted if you are smashing 5 volts on it to fire, as it dwells when high, and fires when low.
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Report this Post01-29-2014 11:01 AM Click Here to See the Profile for conan469Click Here to visit conan469's HomePageClick Here to Email conan469Send a Private Message to conan469Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:


You pull the 5 volts to ground, aka logic wave. You will run the coil inverted if you are smashing 5 volts on it to fire, as it dwells when high, and fires when low.


tomato, tahmahto. it's still a 5v on/off is it not?

quote from megasquirt site you liked to.

"The LS1 coil has 4 connections (as well as the high tension terminal for the spark plug wire, of course):

A = Coil Primary Ground
B = Ignition low noise ground from ECU (ground)
C = Ignition digital signal from ECU (+5V)
D = +12V Supply to Coil Primary"

C?

[This message has been edited by conan469 (edited 01-29-2014).]

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Report this Post01-31-2014 12:58 PM Click Here to See the Profile for DefEddieClick Here to Email DefEddieSend a Private Message to DefEddieEdit/Delete MessageReply w/QuoteDirect Link to This Post
COP for L67?
It's been done,you're just looking in the wrong place unless you really wanna use LS coils or get away from the control module.
Use Ford COP's,wired in series off the stock control module.
Negative ground trigger,should take less than an hour to wire up the circuit. Prob take longer to figure out a good way to bolt em down though.
Am I missing anything?
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Report this Post01-31-2014 04:22 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by DefEddie:

COP for L67?
It's been done,you're just looking in the wrong place unless you really wanna use LS coils or get away from the control module.
Use Ford COP's,wired in series off the stock control module.
Negative ground trigger,should take less than an hour to wire up the circuit. Prob take longer to figure out a good way to bolt em down though.
Am I missing anything?


that's a way of doing it, but not the way I want to do it.
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Report this Post02-01-2014 06:52 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
interestingly enough, this might be much easier then I thought, it might not even require a crank trigger swap.

in tiny tuner:

configuration>main>crank sensor resolution

there are three possible settings, 0,1,2

0 is supposedly the 3x/18x setup like the 3800

1 is supposedly the 7x/24x setup like the 31/3400

2 is supposedly the 24x/24x of the LX5.

maybe take the LX5 programming and change the setting to 0 or 1?

I'm not sure whether this changes the whole ignition scheme, or just the crank sensor. to find that out, would require to either test it on a bench, or to be able to understand the actual code.

Edit:

I'm slowly looking at the code following this byte, and so far, it's identical to the 3400 LA1 bin I'm comparing it to.

FWIW, winOLS says the bin file for the LX5, L67, and the LA1 are 81% identical.


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[This message has been edited by ericjon262 (edited 02-01-2014).]

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Report this Post02-02-2014 12:09 AM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ericjon262:

interestingly enough, this might be much easier then I thought, it might not even require a crank trigger swap.

in tiny tuner:

configuration>main>crank sensor resolution

there are three possible settings, 0,1,2

0 is supposedly the 3x/18x setup like the 3800

1 is supposedly the 7x/24x setup like the 31/3400

2 is supposedly the 24x/24x of the LX5.

maybe take the LX5 programming and change the setting to 0 or 1?

I'm not sure whether this changes the whole ignition scheme, or just the crank sensor. to find that out, would require to either test it on a bench, or to be able to understand the actual code.

Edit:

I'm slowly looking at the code following this byte, and so far, it's identical to the 3400 LA1 bin I'm comparing it to.

FWIW, winOLS says the bin file for the LX5, L67, and the LA1 are 81% identical.



Wont change the ignition module. The ICM handles all of the spark side of the motor, the PCM sends modifications to base timing to the ICM and reads the ICM outputs to operate knock control and fuel injection.
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Report this Post02-02-2014 12:18 AM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:


Wont change the ignition module. The ICM handles all of the spark side of the motor, the PCM sends modifications to base timing to the ICM and reads the ICM outputs to operate knock control and fuel injection.


gotcha. I was also just thinking about how the LA1 style ignition module reads the 7x sensor, and the PCM has to receive the signal from there, so a change in the programming won't account for the lack of signal from the ignition module as far as I can see, thus a trigger swap is still in order so far.

unless the 7x signal can be sent directly to the PCM, assuming the ICM sends a 7x signal.

Edit:

from what I see, the output of the ICM(to the PCM) is the same as the input, so it may be possible to run a 3 wire crank sensor and wire the signal directly to pin 8 of the blue connector. I'll test the output signal once I've got an oscilloscope on hand.


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[This message has been edited by ericjon262 (edited 02-02-2014).]

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Report this Post02-02-2014 04:20 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
The crank sensor output is analog while the ICM output is digital.

Does the ICM send the 7th pulse to the ECM? I thought it only sent 6 pulses (IE, 3x per revolution) and kept the 7th for its own internal use to understand which coil to fire for each ignition event.
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Report this Post02-02-2014 06:51 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:

The crank sensor output is analog while the ICM output is digital.

Does the ICM send the 7th pulse to the ECM? I thought it only sent 6 pulses (IE, 3x per revolution) and kept the 7th for its own internal use to understand which coil to fire for each ignition event.


obd2 3800 gets some form of cam signal with both crank signals for knock detection reasons I believe. I do know that most all DIS generally only output a "distributor" type signal to the ecu... but a obd2 is also sequential injection as well.

Random info on what the outputs of the ICM look like.

RPM sensor = either a square wave or an A/C signal,
Purple and white = a square wave anytime the engine is cranking or running,
White = a pulse width modulated square wave when the engine is running,
Tan and black = zero volts while cranking and 5 volts otherwise,
Black and red = ground.

[This message has been edited by darkhorizon (edited 02-02-2014).]

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Report this Post02-02-2014 09:01 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
The Northstar ICM works similarly.
It reads the 32x wheel from dual crank sensors and the cam position sensor. These are analog signals which have significant peak and slope to them.
The ICM outputs a 4x, a 24x and a 1/2x 0-5V digital signals to the PCM. For an 8 cyl, 4x per rev = 1x per ignition event and 24x per rev = 6x per ignition, which is the same idea as the 3x and 18x on a 3800.

I'm pretty sure that the V6 modules don't pass the sync pulse to the PCM. The PCM doesn't need to know that... it just needs the 3 equally spaced pulses. The cam sensor signal necessary for sequential obviously can't come from the crank trigger wheel.
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Report this Post02-03-2014 04:12 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
I'm not 100% sure, the sync signal may get filtered out, I'll test to see for sure once I get my oscilloscope. but FWIW, the pin that recieves the signal from the ICM in the LA1 programming, receives an analog signal in the LX5 programming, so I think the PCM would be fine with the analog signal.

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Report this Post02-03-2014 04:27 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:


I'm pretty sure that the V6 modules don't pass the sync pulse to the PCM. The PCM doesn't need to know that... it just needs the 3 equally spaced pulses. The cam sensor signal necessary for sequential obviously can't come from the crank trigger wheel.


On a 3800, BOTH the 18x and 3x crank sensor signals get passed along to the PCM from the ignition module. The PCM sees both the 3x and 18x signals.

On the 1999 Shortstar (3.5 DOHC V6), the crank sensor assembly sends both the Crank Sensor A and Crank Sensor B signals directly to the PCM. Then the PCM controls 2 separate ignition modules (one for each bank). The schematics I have for the 3.5 DOHC ignition modules show those modules as nothing more than switching circuits (transistors) to control the ignition coils for each cylinder. So the PCM in this application controls the firing of each individual coil directly, via a transistor switching circuit.

THE MAJOR DIFFERENCE between the 3800 and 3.5 DOHC ignition systems is that the 3800 Ignition Module can fire the coils independent of PCM interaction - as this happens every time on startup (PCM does not take over timing advance control until engine RPM exceeds about 400 rpm). Therefore, all the PCM is needed for is to tell the ignition module when to fire the coils (advance or retard relative to TDC) - the module itself determines what coil to fire in sequence. I believe the 1999-earlier Northstar ignition module functions in a similar way.

On a 3.5 DOHC application, the ignition modules are nothing more than amplifier switches controlled by PCM outputs and have no independent control over the ignition coils themselves. Very similar to how LS ignition controls work, except that there are only two modules containing 3 coils each, instead of 1 module per coil like the LS engines used. However, actual operation should be very similar if not identical.

On paper, it looks like you could wire up LS ignition coils/modules to a 3.5 Shortstar in place of the factory Shortstar module/coil assemblies and it may work fine.
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Report this Post02-03-2014 10:24 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
something else to consider with the direct input of the 7x signal, as far as i know, the 24x signal on the 3400 doesn't have a sync pulse like the 24x from the shortstar, and like I think (been wrong before!) the 3800 has on the 18x signal.

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Report this Post02-03-2014 11:45 PM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by DefEddie:

COP for L67?
It's been done,you're just looking in the wrong place unless you really wanna use LS coils or get away from the control module.
Use Ford COP's,wired in series off the stock control module.
Negative ground trigger,should take less than an hour to wire up the circuit. Prob take longer to figure out a good way to bolt em down though.
Am I missing anything?

Is there a particular reason why you wire the coils in series, rather than parallel?
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Report this Post02-03-2014 11:58 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Blacktree:

Is there a particular reason why you wire the coils in series, rather than parallel?


I think he is referring to wiring two coils to one set of posts on the ignition module. either way, it's a bit hackish for my tastes.
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Report this Post02-04-2014 11:01 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Darth Fiero:

On a 3800, BOTH the 18x and 3x crank sensor signals get passed along to the PCM from the ignition module. The PCM sees both the 3x and 18x signals.


The point I was making is that the ICM generates the 3x signal based on a 6+1 trigger wheel. The ICM does NOT generate a +1 sync pulse for the PCM.

The trigger wheel has 6 primary notches to allow it to be used on 4 or 6 cyl... The ICM can count two trigger pulses for every pulse it outputs for 6 cyl operation or count 3 for 4 cyl operation. It uses the same concept as the Bosch 60-2 wheel, in which the engine controller counts an integral number of pulses for every ignition event depending on how many cylinders it's operating. 10 pulses for a 12 cyl, 12 for a 10, 15 for an 8, 20 for a 6, 24 for a 5, 30 for a 4, 40 for a triple, 60 for an inline twin and 120 for a single.

 
quote
Originally posted by Darth Fiero:
I believe the 1999-earlier Northstar ignition module functions in a similar way.


Yes, the Northstar ICM functions VERY similarly to the V6 ICM.
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Report this Post02-04-2014 11:03 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post

Will

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Member since Jun 2000
 
quote
Originally posted by ericjon262:

something else to consider with the direct input of the 7x signal, as far as i know, the 24x signal on the 3400 doesn't have a sync pulse like the 24x from the shortstar, and like I think (been wrong before!) the 3800 has on the 18x signal.



Does the Shortstar use a 6+1 wheel? I thought it used the same trigger wheel as the Northstar.
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Report this Post02-04-2014 12:25 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by ericjon262:

something else to consider with the direct input of the 7x signal, as far as i know, the 24x signal on the 3400 doesn't have a sync pulse like the 24x from the shortstar, and like I think (been wrong before!) the 3800 has on the 18x signal.


Sync pulse in the 3800 as far as the PCM is concerned is identified by the cam sensor.

 
quote
Very similar to how LS ignition controls work, except that there are only two modules containing 3 coils each, instead of 1 module per coil like the LS engines used. However, actual operation should be very similar if not identical.


Pretty big difference. And you dont know what phase is used (dangerous thing to not know). You could be firing the coil on the falling edge instead of the rising edge of the logic pulse.. which would throw off timing by xxx amount and ruin your dwell.

By 2 modules are you refering to the coil packs or the PCM circutry?
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quote
Originally posted by Will:


The point I was making is that the ICM generates the 3x signal based on a 6+1 trigger wheel. The ICM does NOT generate a +1 sync pulse for the PCM.


There is no 6+1 trigger wheel on a 3800. The reluctor wheel on a 3800 consists of actually 2 separate wheels. One wheel consists of 3 unequally spaced and unequally sized interrupter elements and the other consists of 18 equally spaced and sized interrupter elements. This setup allows both the PCM and the ignition module to determine crankshaft position in less than one full crank revolution.

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quote
Originally posted by darkhorizon:


Pretty big difference. And you dont know what phase is used (dangerous thing to not know). You could be firing the coil on the falling edge instead of the rising edge of the logic pulse.. which would throw off timing by xxx amount and ruin your dwell.

By 2 modules are you refering to the coil packs or the PCM circutry?




As you can see, there are two separate ignition modules on the 3.5 DOHC LX5 engine. What's peculiar about this schematic is it also shows what's inside each ignition module, which isn't common for GM schematics. And if we can take what the schematic shows literally, then each coil driver inside the module consists of a simple power amplifier transistor. I would think this would make the falling edge of the PCM signal to each transistor fire the coil while the leading edge of the signal would begin the coil charging process, making the total "on" time of the signal the amount of dwell each coil receives. That is, if we can take what the schematic shows at face value.

I am willing to bet the LS coils / modules work in much in the same way (ie: leading edge of signal starts the coil charging process and the coil fires on the falling edge).

[This message has been edited by Darth Fiero (edited 02-04-2014).]

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Report this Post02-04-2014 04:31 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:


Does the Shortstar use a 6+1 wheel? I thought it used the same trigger wheel as the Northstar.


no it doesn't, it uses 2 alternating 24x wheels from what I have read. main point I was trying to make is that the PCM shouldn't have a problem interpreting the analog signal.

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ericjon262
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ericjon262

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quote
Originally posted by darkhorizon:


Pretty big difference. And you dont know what phase is used (dangerous thing to not know). You could be firing the coil on the falling edge instead of the rising edge of the logic pulse.. which would throw off timing by xxx amount and ruin your dwell.

By 2 modules are you refering to the coil packs or the PCM circutry?



the ignition control modules. like I've said, I plan to try and test the output here soon to see exactly what we get.
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Report this Post02-04-2014 05:19 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:
Sync pulse in the 3800 as far as the PCM is concerned is identified by the cam sensor.



That's what I thought.

 
quote
Originally posted by Darth Fiero:

There is no 6+1 trigger wheel on a 3800. The reluctor wheel on a 3800 consists of actually 2 separate wheels. One wheel consists of 3 unequally spaced and unequally sized interrupter elements and the other consists of 18 equally spaced and sized interrupter elements. This setup allows both the PCM and the ignition module to determine crankshaft position in less than one full crank revolution.


Ahh... ok. Thanks.
Sounds similar to what GM did with the OBDII 60 degree engines... added an external wheel with the high pulse rate while retaining the internal wheel with the low pulse count. Interesting that they went 18x on the 3800 but 24x on the 60 degree engines.
Do you know what the PCM's did with the signals internally? I was under the impression that the 3x was still used for timing and fueling, while the 18x or 24x was used for misfire detection.

Does the 3x wheel date back to the Turbo 3.8 days?

 
quote
Originally posted by ericjon262:

something else to consider with the direct input of the 7x signal, as far as i know, the 24x signal on the 3400 doesn't have a sync pulse like the 24x from the shortstar, and like I think (been wrong before!) the 3800 has on the 18x signal.


 
quote
Originally posted by ericjon262:

no it doesn't, it uses 2 alternating 24x wheels from what I have read. main point I was trying to make is that the PCM shouldn't have a problem interpreting the analog signal.


Then what are you referring to regarding "direct input of the 7x"?

Two alternating 24x trigger wheels sounds like an LS1 trigger wheel.

Does the Shortstar have one crank sensor or two?

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quote
Originally posted by Will:


Sounds similar to what GM did with the OBDII 60 degree engines... added an external wheel with the high pulse rate while retaining the internal wheel with the low pulse count. Interesting that they went 18x on the 3800 but 24x on the 60 degree engines.
Do you know what the PCM's did with the signals internally? I was under the impression that the 3x was still used for timing and fueling, while the 18x or 24x was used for misfire detection.

Does the 3x wheel date back to the Turbo 3.8 days?


As a matter of fact, it does. The 3x irregularly spaced reluctor first showed up in the SFI Buick 3.8 engines. Later, GM added the 18x reluctor to add a "fast start" capability to the Buick engines. (With only a 3x reluctor, it could take one full crank revolution before the first spark could occur because the ignition module would have to determine crank position so it could sync the coils up correctly). With the 18x and 3x combo sensor, that can happen as soon as 120 deg of crank rotation.

The 3x crank sensor and coilpack ignition was the first of its type used on a GM engine, to my knowledge, and that happened in 1984. The next engine to get DIS and a crank sensor (the 2.8 MFI) didn't get it until 1987 model year.
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Darth Fiero

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quote
Originally posted by Will:

Does the Shortstar have one crank sensor or two?


Two. And it is very possible that it could be identical to the LS's dual 24x sensor setup.

For the record, nothing else in GM's line uses the 3x/18x type crank sensor except the Buick 90 deg V6 engines.

[This message has been edited by Darth Fiero (edited 02-04-2014).]

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Report this Post02-04-2014 07:54 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Darth Fiero:


As a matter of fact, it does. The 3x irregularly spaced reluctor first showed up in the SFI Buick 3.8 engines. Later, GM added the 18x reluctor to add a "fast start" capability to the Buick engines. (With only a 3x reluctor, it could take one full crank revolution before the first spark could occur because the ignition module would have to determine crank position so it could sync the coils up correctly). With the 18x and 3x combo sensor, that can happen as soon as 120 deg of crank rotation.

The 3x crank sensor and coilpack ignition was the first of its type used on a GM engine, to my knowledge, and that happened in 1984. The next engine to get DIS and a crank sensor (the 2.8 MFI) didn't get it until 1987 model year.


The Northstar's combo of two sensors and pulse width encoded wheel supposedly allowed the ICM to sync in 90 degrees. From there it would be at least another 180 degrees before first fire as the PCM has to fire the injectors and a cylinder has to draw in and compress some mixture.

A 3x wheel with pulse width encoding should allow the ICM to sync in 240 degrees of crank rotation, then two pulses for the ECM to fire injectors.

Random thought of the day: A direct injected 8, and maybe even 6 cylinder engine might not need a starter motor, if the PCM can remember where its cycle the engine stopped after the last shutdown. Figure out which cylinder(s) is on its power stroke, inject a little fuel, light it and it might have enough juice to get the engine started.

 
quote
Originally posted by Darth Fiero:


Two. And it is very possible that it could be identical to the LS's dual 24x sensor setup.

For the record, nothing else in GM's line uses the 3x/18x type crank sensor except the Buick 90 deg V6 engines.



The LS 24x used two sensors in one module to read the double wheel.

Two separate sensors may mean it uses the Northstar wheel.
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Report this Post02-04-2014 09:27 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonEdit/Delete MessageReply w/QuoteDirect Link to This Post
fuel doesnt really burn very well without compression.
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Report this Post02-05-2014 10:19 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by darkhorizon:

fuel doesnt really burn very well without compression.


Gasoline burns quite well in a variety of situations. It doesn't have to have a full hit... just enough to get the next cylinder to fire
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quote
Originally posted by Will:


The LS 24x used two sensors in one module to read the double wheel.

Two separate sensors may mean it uses the Northstar wheel.


I meant to say two crank sensor signals. It is still a one-piece sensor that has two sensing elements in it. Probably very similar if not identical to an LS 24x setup.

[This message has been edited by Darth Fiero (edited 02-05-2014).]

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Report this Post02-06-2014 10:24 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Darth Fiero:

I meant to say two crank sensor signals. It is still a one-piece sensor that has two sensing elements in it. Probably very similar if not identical to an LS 24x setup.



Ahh... ok. That's interesting.
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Report this Post02-06-2014 12:44 PM Click Here to See the Profile for ericjon262Send a Private Message to ericjon262Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Will:


Then what are you referring to regarding "direct input of the 7x"?

Two alternating 24x trigger wheels sounds like an LS1 trigger wheel.

Does the Shortstar have one crank sensor or two?


as Darth pointed out, the short* has two sensors in one housing.

both sensor outputs go directly to the PCM, no ICM in between, this is also what I was referring to by direct input of the signal, bypassing the ICM. the Signal from the ICM is input on the same pin as one of the 24x signals on the short*, so I don't think the PCM would have a problem interpreting the signal either.

I've compiled a list of pinouts the V6 PCM uses, along with a little bit of other useful info/features, all located here:

http://www.gearhead-efi.com...98-GM-V6-PCM-pinouts
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[This message has been edited by ericjon262 (edited 02-06-2014).]

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