The MegaSquirt Project has experienced explosive growth other the years, with hundreds of new MS installations occurring every week - a phenomenal success! MegaSquirt has been successfully used in all aspects of Internal Combustion engine applications including R&D, Industry, Race, and Research. The MS project has transformed itself from a simple R&D project into a full-featured mature engine control system. To reflect this the support structure has also changed to meet the needs of MegaSquirt Users.
Moving forward, the R&D forums for MegaSquirt project are in a read-only mode - no new forum posts are accepted.
However the forums will remain available for view, they still contain a wealth of information on how MegaSquirt works, how it is installed and used. Feel free to search the forums for information, facts, and overview.While the R&D forum traffic has slowed in recent years, this is not at all a reflection of Megasquirt users, which continue to grow year after year. What has changed is that the method of MegaSquirt support today has rapidly moved to Facebook, this is where the vast majority of interaction is happening now. For those not on Facebook the msextra forums is another place for product support. Finally, for product selection assistance, all of the MegaSquirt vendors are there to help you select a system, along with all of the required pieces to make it complete.
Forum rules Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
installed in a motorcycle, Suzuki DR 650 engine (1 cyl wasted spark))
trying to get constant tach signal here... signal seems to be clean up to the MS box now after several tries with the pots... my problem seems to be in selecting the right setting in Megatune now.
using a 6-1 wheel welded on flywheel with the first teeth after missing one lined up at tdc. using these settings in MS.
the tach signal seems to be counting the number of teeths passing instead of counting rpm. And changing the Delay teeth actualy changes the number it gives out!? it should not cuz it should only change advance output to ignition, not rpm reading right!? Kinda confused now !! thanks for your help
P.S. getting a lot of resets too but i think it's just cuz of starter motor spikes.. how could i solve that issue? cuz sometimes Megatune just didnt want to reconect to MS while cranking, i needed to cycle power to get connection back.
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Have tried diferent settings ... still have the same problem. LED D14 seems to light acoording to real engine speed tho.... but megatune's RPM reading is just counting the number of teeths instead of reading rpm...
My MS2 was bought assembled from DIYAutoTune so this should eleminate the question of hardware problems.
I'm getting a friend's scope this w-e to check things out but i dont think the problem is hardware related.. the tach in MT seems to counts every tooth that passes in front of the trigger...
not weven trying to start the bike yet, just want decent readings from MT while cranking... waiting for my inline fuel pump.
My MSD6 box is bolted directly beside the MS, is this a problem? I heard it could cause some spikes/interference.. It's not plugged for now anyway, trying to drive the coil directly from high current driver.
Kind of stuck now... could someone please give me a hint?
This looks like a case of a bad tach signal, but the controller keeps compensating for it, so the rpm keeps increasing but it's really not. That is one possibility. The other is that this is the first time anyone has tested 1 cylinder with wheel decode. I will try to run your msq tonight and see what is going on. The most puzzling thing is that the delta_t, which should reflect the rpm, jumps between 2 values: .128 secs and .186 secs, corresponding to 468 and 322 rpm, all the while the calculated rpm is very smoothly rising like a realistic, perfect startup.
By all means get a scope shot of the tach input - if it is bad, no need to go further, If looks good, then scope the output.
OK I found two things, the first of which explains a lot about what is going on. You have most all the lag factors set to 20 and rpm set to 2. However, a lower number means more lag not less, and 2 % means rpm takes many seconds to get up to speed. I know this is stupid, but I did it to be in conformance with GM who did it that way, and from what I read that appeared to be the standard. Never follow the crowd.
Anyway, you want to set all the lags to something between 70 and 100 to start. I personally would use 100 (no lag) for everything until I saw a need to reduce it because of too much jitter. It should be very rare to go less than 50%. I think when you do that the rpm will make much more sense.
The other thing I found is that the rpm displays at 2x what it really is, because you have 1 cylinder wasted spark. I need to put a line in the code to correct for this. I will do this before you start tuning, so the VE values will be in the right rpm bins.
could'nt resist trying it right away it works fine now... well at least the tach signal reads 306 to 309 RPM when cranking so i guess it's dead on! Thanks a Lot Grippo, i could'nt have found out about this myself.
just have to solve spark issue and i'm good to fire up the beast!
P.S. Just wondering, would it be easyer to drive a GM twin tower coilpack directly from the MS or drive my MSD6 ?
The MSD does work properly cuz when i toutch ground with the white wire, it sparks. but MS will not trigger the MSD's white wire (set at 25* dwell and spark duration...also tried normal spark settings)
MSD is my prefered way to go cuz i run 11.5:1 C.R. on 3''3/4 diameter piston... need a really good flame! Twin spark head.
I would use the MSD. There is no reason MS shouldn't trigger MSD - many people have done this. Read the manual on setting up MS2 for MSD and search forum posts for problems people have had and their solutions.
allright, i figured why the ignition was not working... the pre built MS was wired not to use the high current driver. Figured it out cuz i was getting ocnstant 5v out of the pin 36
So i got it to sputter last night, gonna losse some advance cuz engine tends to kick back instead of starting.
sputter seemed too constant (always fired 3 times before dying)
so i checked it spark plug out... and it goes like this spark...spark...spark...nothing...spark...nothing...spark...nothing...spark...spark...spark...nothing...spark...nothing...spark...nothing...spark...spark...spark..., etc
not sure if it's quite clear... anyways, i wonder what can do this.
changes since last time include a bottle to dampen the map reading a little which seems to have worst effect than a flow restriction trough the hose (might need both)
what is a reasonable map deviation at idle ??
here's the log of my latest testing
thanks for your help
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If you plot your rpm (or deltat_t from the last few columns) against the time in the first column you will see that the rpm jumps back and forth from 600 to 300 and the delat_t jumps back and forth from 10000 to 20000 microseconds. This is a direct measure from the tach input signal, so something is wrong there. It is so consistent that I think there is something wrong with your input variables. You were getting a consistent 300 rpm while cranking from your previous post. So either this problem occurs after cranking or you have changed something else. Can you post the msq you used when you generated the datalog and I will test it when I get a chance.
I tested your msq and the output didn't look right, but I got it to work correctly by changing the trigger offset to -30 deg. This means the tach pulse comes in 30 deg after tdc, so you have to adjust the location of your sensor so this is true. There is nothing magic about 30 deg, you just need some separation between the tach coming in and when the spark is fired. It may be that +x deg may also work, if that is more convenient.
Since this isn't dual spark mode, this separation generally isn't needed. I don't know why it is needed in your 1 cylinder case, plus you shouldn't have to set it up as two cylinder. I will put this on my list of things to do.
i'm not sure i understand what you mean... you're saying that the problem is caused by my trigger being spot on tdc?
dont really want to move the trigger now cuz the ring has been welded on my flywheel and triger itself can not be moved in the engine... there is a boss in the cover only for the sensor.
What is the +x deg??
Ok, so if i get this right, i could trigger the tach from the trailing edge (tooths being exactly 30 deg wide) and play with trigger offset (-30deg) to have the spark timing back to tdc?
Or trailing edge of the last tooth before tdc and give it +90deg trigger offset..?
The Benz Master wrote:
Ok, so if i get this right, i could trigger the tach from the trailing edge (tooths being exactly 30 deg wide) and play with trigger offset (-30deg) to have the spark timing back to tdc?
i did'nt have it fire from the trailing edge tho, did'nt work... i tried it with 1 and 5 skip teeth without any trigger offset and with proper trigger offset, tried to play with some other misc parameters... always the same problem or no spark at all.
one thing that got me wondering.. while i crank, the "not cranking" text lights up in the bottom of megatune so i tried to move max cranking speed up or down to see what would hapen but other than a certain rpm range (+- 350 to 500), i just did'nt get any rpm signal eccept maybe 1 sec from start.
Been thinking about it and what i changed since the spot on rpm signal is that i wired the board to use the high current driver instead of 5v output.
Too many things are being changed here. Step 1 is to get a clean input signal into MS such that the rpm is consistent. You can play with output drivers all day and this should have no impact on the rpm, unless they are not connected properly or cause noise.
So let's start with the input. You said you got a good input and rpm at some point. Can you get back to that state ? By that I mean that a datalog shows rpm climbing and leveling out during cranking with no spikes or drops to 0. You can disconnect the injectors to test this. If you can't achieve this then you have to scope your input signal. If you do achieve it, then you need to start scoping the output signal starting at the gate to the coil driver. For the latter, you can disconnect the coil as well as the injectors.
Ok, it's not clear to me... ignition output from MS seems to be prety constant... i did'nd get to try it with the MSD pluged tho, i have to wait battery recharge !!
The red TDC mark i think is at the end of compression cycle cuz piston speed verry slow (lots of compression) then things speed up for explosion and exhaust stroke and (blue TDC mark) slowing down again for intake and compression stroke. (engine not running... only starter is pushing)
I'm not sure of consistency between the two, i dont really know how the scope works ... just got lucky and got some readings out of it
One of the possibilities would be that this triggering just as the red TDC goes is just borderline of being detected by MS and this whole thing has the MS missing a few sparks... but i tried both pots up to both limits without any results...
i'll try to scope both output at the same time and get the MSD working while i scope now... Any info/advice will be well apreciated
OK, i dont know why, today it seems to be even fire but i think that today it just misses the small 4v spike just before combustion (instead of catching it randomly making the rpm drop 1/2 !??) cuz it seems to fire only at the overlap between intake and exhaust stroke.
P.S. I often get "blank screen" in megatune.. all gauges turn red like if MS was disconnected and nothing hapens.... could it be because voltage drops too low when i crank the engine? I'm not sure what to do, i got a full size car battery cranking my bike ... i dont want to see what it will be with a bike battery !!
it works fine now... well at least the tach signal reads 306 to 309 RPM when cranking so i guess it's dead on! Thanks a Lot Grippo, i could'nt have found out about this myself.
