MicroSquirt.com read only forum (Jan.15,2018)

Well,

this is the new thread that I was supposed to start in order not to mess around with that other sticky one.

As I mentioned before, the wire that I had to interrupt on the Bosch ignition module in my Saab, which is a 139 module, is on pin 6 and not 5. I do not know whether there are differences between those modules but I just wanted to let everybody know that with this kind of module the ignition setup will not work as described in the megamanual.

I have a nice signal on my scope now, which switches between ground and 12V - unless I plug in the MS-II. At that moment I have 0V all the time.

I suppose, that I need to install a pull up to 12 V now, because the Hall signal output seems to be to week. This is a little surprising for me, as I thought that the pull up is only needed in cases were the Hall signal switches between 5V and ground. I'll try the pull up within the next days.

Cheers,

Tadek

Hi everybody,

just to pass on this information, yesterday I learned that the 139 module that is installed in my Saab turbo will probably not work with MS-II at all. I knew that it is a smart module from another post, but I did not know that I have to have a pulse width ratio of 40/60 or 60/40 in the module's input to have it work.
Therefore I will use the Hall signal for MS-II and then use the high current driver to drive the coil directly as suggested by many others before.
Sorry about misinterpreting a few things, but I assumed that the Bosch modules all have the inputs and outputs on the same pins.

Cheers,

Tadek

Tadek wrote:but I did not know that I have to have a pulse width ratio of 40/60 or 60/40 in the module's input to have it work.

How did you find that out? Very interesting...

Ian.

Well, 50/50 or something like 40/60 or 60/40 depending on your definition is about the pulse width ratio when using the original shutter wheel and Hall sensor. I heard from guys using MSnSE code that you can have this kind of output signal with MSnSE but you cannot with MS-II as far as I have understood. Keith G told me that tht 139 module expects this 40/60 ratio to work properly. Therefore you would have to change to a "dumb" 124 module to run ignition with MS-II and if you have to change things and modules and wiring anyway, you can go with the high current driver as well.
El-hardo is another guy who had to change the modules to get ignition running with MS-II on his Saab.

you can have this kind of output signal with MSnSE but you cannot with MS-II as far as I have understood.

Tadek,

You can adjust the duty cycle of the ignition output on MS-II by adjusting the ratio of the dwell to the max spark duration. See this thread for example: http://www.msefi.com/viewtopic.php?p=100401#100401

I'll document this more fully soon.

Lance.

I already istalled the high current circuit and now added a couple of 1K pull-up resistors on input and output of MS-II, but now I will try to operate my Bosch 139 module with the boosted output, first.

I read that other thread about dwell/maximum spark duration ratio and tried those adjustments on megatune, but it will not allow me to set the dwell to 16ms like proposed, as the highest possible value is 8.

I am using Megatune 2.25 beta at the moment and downloaded MT 2.25 and MT 3.00 beta just to try them, but I cannot get them running as I get the error "settings.ini" cannot be opened and then MT is terminated.
Is there anything that has to be set up after the installation first, which is different to the MT 2.25 beta version?

Cheers,

Tadek

it will not allow me to set the dwell to 16ms like proposed, as the highest possible value is 8.

Tadek,

Yes, this is a limit built into MegaTune to keep people from frying their coils (when used in other applications).

To change the limit, find megasquirt-II.ini in 'C:\Program Files\MegaSquirt\MegaTune2.25\mtCfg' (it might be in the project folder, depending on how you set things up), and change the line that reads:

max_coil_dur = scalar, U08, 4, "ms", 0.10000, 0.00000, 1.00, 8.00, 1 ; * ( 1 byte)

to

max_coil_dur = scalar, U08, 4, "ms", 0.10000, 0.00000, 1.00, 25.00, 1 ; * ( 1 byte)

Then you should be able to put in up to 25 milliseconds.

Lance.

Thanks, I'll try that.

Concerning MegaTune 2.25 not running I'll post in the appropriate forum.

Hi,

tonight I tried running my MS-II together with the 139 module. To do this, I modified the Megasquirt-II.ini to allow a dwell duration of 16ms and spark duration of 25ms as proposed in one of the former posts.

I get a nice Hall signal which I first had a look on with a scope. It is a nice square signal between 0V and approx. 9V when connected to the module.

When I interrupt the wire to the module and feed it to MS-II while feeding the MS output to the module, I get a signal between 0V and and 3.8 V on the MS-II input, though I have a 1K pull-up resistor installed there. Should I reduce the value of this resistor or leave it as it is?

On my output of MS-II I have a voltage between 1V and 6,5 V with the pull-up resistor removed from the high current driver output. With the 1K resistor in place, I had a constant voltage there (I cannot remember the value), which dropped only slightly when it was supposed to be going low.
Therefore I removed the resistor.

I used a setup with the ignition advance set to 16° BTDC as it is supposed to be when using the standard distributor ignition and accordingly I set up the trigger advance in MegaTune.
Is it possible to get the engine running properly this way, or is the duration of 180° CA too long in between two triggers (or better between trigger and spark!) to get a properly timed spark?

Anyway I got the engine started but the idle was very erratic. The input signal from the Hall sensor is nice and steady but the output does vary a lot in timing no matter what predictor algorithm I tried to use. I am not sure whether the voltages mentioned above are enough to fire the ignition module anyway. Should I reinstall a pull-up resistor with a higher value on the high current driver output?

What is the maximum trigger offset angle that can be used? I thought that if 180° is too much, I might use the other edge of the shutter wheel without turning the distributor and just invert the input capture?! But 120° BTDC are probably still too much and that is how much it probalby would be

If the engine would not stall so qickly, I could use a timing light to see where the ignitions occur and whether there are cycles with the spark missing.

Any suggestions on whether to try to reinstall a pull-up resistor on the high current output or what to try next?

Cheers,

Tadek

This sunday a had a little time to have a look at my MS-II installation with the Bosch 139 module.

First of all I took another 4 channel scope from work in order to get a clue what is going on with the Hall signal as an input for the Bosch module and how this correlates to the module's output to the coil. I turns out that as expected ignition occurs the moment the Hall signal goes from high to low.

Next thing I did is that I replaced the 2.1 firmwar with 2.34 firmware that I downloaded to my laptop some time ago. After this I reimported my ignition maps that I prepared beforehand.
After setting the maximum dwell time to 25ms and the maximum spark time to 16ms with the ignition advance set to 16° and other settings being:

Ignition Input Capture: rising edge
Cranking Trigger: trigger rise
Coil Charging Scheme: normal
Spark output: going low

I managed to get the identical output from MS-II that I was receiving from the distributor Hall sensor with the engine running. This means, I had the engine running with the Hall signal going to the Bosch module, MS-II and the scope, of course. Additionlly I had the MS-II output on another channel of the scope.

My new problem is that since yesterday I do not get any ignition output from MS-II when the engine is cranking. It says it is cranking on MegaTune, but I do not get any output, anyway.

I have no idea what might have caused this, as the output works as long as the ingine is running and it did work with the engine cranking, as well, but this has been tested a while ago.
Any ideas what might be the problem? Is it possible that the newer version of firmware is making trouble?

Cheers,

Tadek