Engine runs but has hard time starting

[sn95.ohh]

So I have a KTM 560 single with a custom efi system running a microsquirt module. The ECU is controlling spark and fuel. My biggest problem is that the engine has an extremely hard time starting. The engine has started many times before but every time it is never on the same tune(just changing initial advance and fuel). I also have a ton of backfire in the intake as well. I have been pulling my hair out going crazy over this issue. Does anyone have any suggestions??

Thank you for the help

[Matt Cramer]

I don't believe 72 is a valid number for skip teeth on a 36-1 trigger wheel - try 36 instead.

[sn95.ohh]

Ok I will give that a shot. Im pretty sure I tried it once and it doubled my rpm signal. But I will give it another shot later tonight.

Also I was a little confused with injection timing delay. With a single cyl do I run it at 0% or maybe slightly higher?

[sn95.ohh]

I still havent tried this yet but I have been thinking about it. Am I making it 36 because I am only running a crank sensor and want a tach pulse every 360 degrees?

[sn95.ohh]

I just tried changing the skip teeth to 36. It seemed to help. It was finally wanting to start. I had puffs of smoke and fire coming out of the exhaust. It would start for a second then just turn off every time I would turn it over. There were still a few problems though. Changing the skip teeth has seemed to cause my rpm to double and be extremely inconsistent. Im guessing this is the reason why it would not run. I will continue to try to find a solution but are there any suggestions to this new problem??

Its oh so close! Thanks for the help!

[Matt Cramer]

I still havent tried this yet but I have been thinking about it. Am I making it 36 because I am only running a crank sensor and want a tach pulse every 360 degrees?

That's correct.

Injector timing delay - I'd start at zero and adjust as needed.

On a purely crank triggered engine, tell the MS it's a two cylinder to get the correct RPM reading.

[grippo]

From your msq you are running an old code. While this can probably be made to work on your setup, I would switch to the 3.780 code and work in Dual Spark mode, that is the proper mode for your setup. Check the links on the V3 microsquirt easy start documents. They describe the auto trigger mode and there is documentation for single a twin engines. You won't have to fake any inputs with this code to get the right rpm. Look at the dual spark options and pick the one that is correct for your setup.

[sn95.ohh]

Thanks alot both of you. I will give it another shot later tonight. I will let you all know how it goes.

Thanks again!

[sn95.ohh]

Alright so I updated the code and still nothing. I think I have the auto trigger feature figured out but I am sure I might be missing a small detail. I did some data logging and noticed that trigger +/- is counting up. And based off of what I read on the auto trigger site this means that it is either receiving noise or the polarity is wrong. I know polarity is right because I had it on an oscope the other day and everything was fine. So could noise be a serious possibility??

I have attached a copy of my new msq and my datalog file.

Thanks aton guys.

[grippo]

Your configuration looks ok and you are getting sync. The trigger+/- counting up can be indicative of noise, but it can also be due to a rough running engine, and a 1 cylinder is naturally much rougher than an 8 cyl. Also, if you aren't firing spark it could be due to timing being wrong because trigger offset is wrong. If you are getting spark, I would try pulling the injector plug so there won't be any combustion and crank the engine and see if you can time the spark and see if it is where you want it. If not adjust trigger offset until it is.

Another thing, turn off the x-tau option - you don't need it until you start tuning acceleration. From the log it is causing some fuel problems during cranking. Also, I would raise the afterstart pulsetolerance from 35 to 50-70%, you probably need the extra slop at this point. Finally, I assume you are using the correct vr/ opto circuit jumper for the type of sensor you have ?