Strange Problem. 20k cranking RPM and software issue

[grippo]

I agree about using 2.890, but in this case I am not sure it will cure anything because I don't see the trgger+/- count changing when you lose synch.

In looking at your msq, it looks like you are not using dual spark option. This is a much more accurate and reliable mode. The only problem is that for your 1 cylinder you would have to tie the 2 outputs together, and if there are not ignition drivers on the outputs (VB921s or Bosch or equivalent) you will fry the processor ports unless you put them into an OR-gate chip and use the single output from that. However, there is a way around this - you can configure your setup (save the original msq so you can roll back if needed) as follows:

Skip Teeth = 12, no_cylinders =2 , 2nd output odd-fire angle = 0.1 deg.

This will give you twice as many sparks on output 1 as you would have needed if ign 2 was tied to ign1, but instead you ignore (don't connect) output 2. The reason for the odd-fire = 0.1 deg (non-zero) is to make the rpm come out right.

However, you will have to adjust your trigger offset to be negative and this may mean a change in delay teeth. There are examples of how to set this in the Dual Spark writeup at microsquirt.info. If tyou do decide to do this, you should use 2.890 code, so try that first as Paul suggested. If it doesn't work, then you can try the above or try extra code.

[Postman]

Al, Paul, Thanks for your replies.

I have tried to upgrade back to version 2.89 (and 2.888), but I still have that issue of not being able to upload the number of trigger teeth in the Advanced Ignition Options. With that said, I have been running 2.886.

A 10K resistor in line with the VR+ wire solved the tack signal issue. Of course, that thread Paul showed me explains how the resistor is a kind of a band-aid fix for that. The 1N4148 diode seems to be the correct way to remedy that. Any idea where I can pick one of those up?

Either way, after solving the rpm break up at 5000 rpm....I have yet another issue occuring at around 6500 rpm.

6.5k.msl

Engine rpm increases nicely up to about 6 grand, where the dwell starts to go nuts. If I run at this speed for more than a few seconds the engine quits all together.

Last night, my thought process was that our coil's dwell setting of 6.1ms was too long to handle the rpms. I also thought that the engine quitting was due to overheating the coil and causing it to quit. Now, I know 6500 is not high for any coil (especially for our MSD LS1 coil), but if i am running wasted spark, isnt the engine firing a spark once for every engine revolution? Perhaps the coil couldnt handle that.


Al, Im curious what running dual spark would do. If I really am running out of dwell time and over saturating my coil, then i fear i may have the same issue i have now. But if it is a more reliable set up I will make the switch.

With all that said, I tried running a Honda CBR 600 f4i coil on our engine, driven by a GM HEI. But Im not sure how to wire that up to a uS, (jumper wires i might need in the uS, wiring conversions from MS2 to uS, etc) seeing as all the directions I have found are for a MS2. I gave it a shot and ended up burnging up a relay...so i figured that was a good place to stop and ask for help.

So long story short, I fixed the 5000 rpm tack signal break up, but now have the 6500 rpm break up. I really want to keep the MSD LS1 coil for packaging reasons, so hopefully im wrong, and the coil is not the problem.

Thanks for the help guys, its less that 3 weeks till our FSAE competition, but i feel that i have plenty of time to get these bugs figured out and put a decent tune on the engine with time to spare.

[SQLGUY]

Actually, if you look further down the thread I referenced, you'll see that I did not agree that the 1N4148 was a real fix. The real fix for me was removing C30.

FWIW, 1N4148's are available from Radio Shack.

With dual tachs you can "run out" of dwell time at higher RPM, because dwell cannot start until the tach signal is received. I don't believe that applies for missing tooth triggering. Here's a thread where dwell issues were discussed: http://www.microsquirt.com/viewtopic.php?f=89&t=22933

Cheers,
Paul

[Bruce Bowling]

So long story short, I fixed the 5000 rpm tack signal break up, but now have the 6500 rpm break up. I really want to keep the MSD LS1 coil for packaging reasons, so hopefully im wrong, and the coil is not the problem.

OK, I have spent countless hours looking into the VR crank issues. It turns out many of them are being caused by noise being introduced by the crankwheel itself during the missing tooth section. What happens is that during this period a tiny blip can show up. At low RPMs the blip is often less than a millivolt during cranking and the hysteresis of the VR circuit rejects this. However as the RPM increases the overall VR signal also increases, and at a certain RPM this "phatom tooth" becomes large enough to exceed the threshold limits.

Inserting a resistor simply reduces the current of the VR circuit loop and hence the detection voltage. This is why adding the resistor just pushes out this RPM to a higher point.

The code has a tooth window in it where, after achieving sync during cranking, there is a region where it expects the next tooth to come in. If a tooth pulse appears outside of this window it is rejected...you can see this happening with the Trigger+/- counter going up or down indicating it had to throw out or add a tooth to maintain sync.

The issue with the earlier code versions is that this check was not working correctly only during the missing tooth section - this is where the phantom tooth is most likely to show up. This was fixed in the latest code revision that is out.

I have a CBR600 engine that would not rev past 6000 rpm. When I added the resistor it would go to 9000rpm. With the latest code and no resistor I am able to rev to 13000 rpm without any issues. When I datalog and run the engine I can see that below 6000 RPM the trigger+/- variable stays at the same count, but when I rev past 6000 rpm the counter starts incrementing - this means there was a tooth coming in when it was not expected and it was thrown out. I can post the datalog for an example on what I mean.

For using the dual-spark code, I would certainly do this for sure. This code has more checks and the wheel decoder is more accurate. Even for a 1-cylinder I would use it - just call it a two cylinder with wasted spark and ignore the second fuel channel....

For the CBR setup I am using a dwell of 2 - 3 msec wth the stock coils. If you run much more than this you will cook them for sure, I have seen it happen. These coils need an external driver, I have been using the one from EFIsource that drives 4 coils: http://www.efisource.com/details.php?category=2&id=21

- Bruce

[grippo]

Al, Im curious what running dual spark would do. If I really am running out of dwell time and over saturating my coil, then i fear i may have the same issue i have now. But if it is a more reliable set up I will make the switch.

The dual spark mode is tooth angle based, so it only has to predict when the next TDC occurs over 1 or 2 teeth rather than from the last TDC (360 deg ago) to the next TDC. This is especially critical for a 1 cylinder. If it were 4 cylinder, it would only be predicting over 90 deg - still a lot. Your spark advance is only as accurate as TDC prediction since it is referenced top that.

Your issue with setting the no. teeth has nothing to do with the code. If you really can't set the teeth in advanced ignition menu, even after you tab and then hit burn, then possibly your ini file has a mistake. If you post your 2.89 ini file and msq I will try it on the bench.

[Postman]

Bruce,

would a Bosch 0 277 100 214 controll unit be a sufficient driver for the honda coil? I have a 0 277 100 203 driver, which i believe to be the 214's equivilant.

Before I go on solving other issues, I have to get my spark back. Since I tried wiring up the HEI module i havent been able to get a spark. Even with the LS1 coil I was using before...

If the bosch unit wont work, does anyone know where i could find a wiring diagram for microsquirt and the HEI module? The MS2 diagram had me a little confused.

[Bruce Bowling]

Bruce,

would a Bosch 0 277 100 214 controll unit be a sufficient driver for the honda coil? I have a 0 277 100 203 driver, which i believe to be the 214's equivilant.

I have not dealt with the 214 driver, but I suspect it should work OK.

- Bruce

[Postman]

So I went ahead and tried to get spark from my LS1 coil - running the previous setup that had worked for me before. Now I get no spark whatsoever. I tried using the bosch module as well, and still no spark. Same wiring, same .msq file. i dont think I am getting a signal from uS. Is there any way I can determine is I fired something in the uS when I tried using the HEI module?

Or better yet...

TC8.msq

(25.11 KiB) Downloaded 53 times

Is there some setting I am forgetting?

I really want to try all the different ideas you guys gave me, but I feel like I should try to resolve this issue first. Maybe I should just upgrade to MS2 extra first. I was even thinking about ditching the uS all together and using a MS2 we have here in the shop. I am under the impression that it was a little less finikey.

Then again, the grass is always greener on the other side of the fence. Especially when its 2 and a half weeks from competition without a running engine.

Oh and Al, here is my version 2.89 .ini file.

megasquirt-II.ini

(113.28 KiB) Downloaded 56 times

Thanks a lot guys.

[grippo]

I will look at your msq and ini file tonight. But your more immediate problem is spark. If when you crank the engine the rpm gauge goes to a reasonable value and fluctuates around it, and never dips to 0 even momentarily, then the ECU should be putting out spark. It may not be when you need it, but there should be spark. I can't think of any config or software issue that would prevent spark if there is Rpm that changes and also a reasonable dwell. If you don't see any spark, then there is either something wrong electrically, the ignition driver or spark output port is fried, or possibly you have the dwell duration too short or spark output polarity set wrong. But this is not likely if you are using the same msq that worked before.

[Postman]

In that case I fear the worst. Ive tried the MSD LS1 coil with its internal drivers, The Bosch Ignition Driver I mentioned earlier with the honda coil, and the HEI with the same honda coil. All three combos gave the same result, no spark. With an ossiliscope connected to the Ignition output I dont see much of a signal either...

Ill do a little more investigating today, but I might just make the swap to the MS2 we have for times sake.