Twice Injector pulses during cranking?

[Blazer79]

I'm trying to start my Camaro for the 100th time. I have a MS2 with board 3.0. Bought it assembled from a friend who gave up on his project. He bought it assembled from DIYAutoTune.

I'm currently on the Stimulator V 2.21. If I start with the RPM pot all the way down and slowly start turning it, as soon as the IGN LED starts blinking, both injector banks start blinking at the same time. Syncronized both with the IGN LED. As I continue to turn the RPMs up and MS senses I'm no longer cranking, the INJ LEDs start taking turns, blinking one at a time, which is what I would expect during cranking. Is it normal to have both banks active at the same time during cranking?

Also the injector pulses are around 3.5ms during cranking and once MS senses I'm no longer cranking, they go all the way to 13ms. This probably explains why the car starts and immediately dies.

Any ideas?

[Bernard Fife]

Blazer,

That's how it is designed to work. During cranking, the fuel is squirted on every tach pulse. Once running, fuel is squirted based on the settings you have set for things like number of cylinders, alternating/simultaneous, etc. See: http://www.megamanual.com/mt29.htm#sc

Squirting on every tach pulse while cranking means the engine is likely to start faster, since it starts injecting from all injectors as soon as it knows the engine is turning (i.e. it sees a tach pulse so there is fuel) and since all injectors are firing, there is likely to be fuel in the next cylinder to have a spark.

Note that because there are many more injections when cranking, the pulse width is generally shorter than while running.

For keeping the engine running after cranking, you might want to check the tips here: http://www.megamanual.com/ms2/tune.htm#howto

Lance.

[Blazer79]

I want to thank everyone who has taken the time to reply to my posts at any point in time. My engine finally fired up today!!

For anyone having the same issues as me, I'd like to leave for posterity how I solved my starting problem.

The problem was in the reqFuel parameter. I had lowered it a lot because at one point I fouled my spark plugs after many unsuccessful attemps at starting it. So I was kind of traumatized and lowered it trying to match 2ms at idle I found in some old datalogs of my original GM ECM. My engine would start, run for about 2 seconds and die, so my cranking and ASE parameters where OK. But as soon as the ASE time finished it switched into using the reqFuel and MAP vs fuel table, that's when it died. A friend recently told me "make it very rich, if there's spark, it should fire". So I slowly started raising and raising the reqFuel each start attempt and noticed it stayed running longer each time. Finally I got to a point where it finally kept running. Rough, but running. Adjusted my throttle body screw to allow a little more air (and recalibrated TPS) and got better this time. RPMs were fluctuating badly now (the engine would eventually die), so I put the same spark advance on the 4 cells where RPMs were fluctuating. Now I got a stable idle. It was until this point where I could check my timing with a timing light. Why can't they make the timing stay still while you're using the cranking wizard? It looks as if at some time, Tunerstudio had a parameter to change your MS to fixed timing. I couldn't find it now.

Now it's tuning time for me. I'll be installing a wideband sensor for this. My knowledge is still limited, but if I can be of any help to anyone, please drop me an email jp at pulgadascubicas dot com