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

This is a recent problem with my MS install that I first got running a little over a year ago. It was starting and running well, but I still had work to do on the timing and fuel maps.

Engine is a supercharged 3800 using MSnS-Extra code for fuel and the C3I ignition.

What's happening is that if I start the engine with no throttle input, it'll fire and the rpms will flare up to 1800 or so rpm, but then decays down to where it finally stalls.

If I start with some throttle, or blip the throttle after start to where rpm hits 3k or so, it'll come back down to my fast idle rpm and be rock steady. This happens all the time, cold, hot, heat soaked, etc.


I've spent a few hours datalogging starups and adjusting my cranking, ASE and warmup enrichments. I've adjusted my 500 rpm VE bins up and down as well. The most I've been able to do is change how long it takes to die after startup. Sometimes it'll die after a couple seconds, sometimes it takes about 15 seconds.

I'm having a hard time figure out if it's dieing because it's too rich or too lean. It seem rich cause it kinda coughs and sputters and the exhaust is very noxious. But some datalogs show that the rpm drags all the way down to 300 (my crank rpm), then the PW spikes because MS goes into crank mode and the rpms jump back up. That kinda makes it look like it's running lean.

But, *always*, if I rev the motor either during startup, or sometime after startup before it stalls, the rpm comes back down and idles perfectly. It literally acts like bliping the throttle throws a switch somehow to make it run.

This link is to a couple of the sample datalogs and my .msq file. The logs show the startup's with not throttle and the gradual RPM decay until it stalls, and startups where I blip the throttle and it idles fine. I've been trying to identify what's different between where the idle drops and stalls, to where it's stabalized after the throttle blip and haven't been able to figure anything out yet.

Any ideas where to go?

--Dan

I had a look at your msq. You could try a couple of things. Looks like GammaE is turned off on both injector banks under "Fuel Table Selection". This probably won't help you much. Injector 2 is turned off during cranking too? The baro correction values to help during processor resets look extremely low, will not help if you have any resets. In later codes the ASE won't work unless the values entered are above 100%, so put in 140% instead of 40%. It's possible you have no ASE happening. Best to check this on the stim to confirm. In accell wizard usually the highest tps dot rate is in the top bin, not the bottom bin, don't know if this will cause a problem or not.

I would be inclined to enable GammaE on both injector channels, switch on inj 2 during cranking (unless it's starting fine just as it is), and put a number 1 in front of all your ASE entries. But do so at your own risk, I am no expert.

Ian.

my car kinda behaves similar. Starts... seems fine, for few seconds (i run very little ase, so ase is not an issue i think) then slowly rpm's drop and at some stage drop to very low (engine bucks ans stumblkes) and in most cases engine will die, unless i help it with some throttle... I'm thinking it might be running too rich.... once 2.685 code for ms2 is fixed then i'll do some more tuning ;)

newtyres1 wrote:I had a look at your msq.

Ian, thanks for pointing those out. I'm not sure how the inj2 got turned off and I updated the ASE fields as well. No change though.

This was frustrating. I played with it for another hour after work and it really seemed that no matter what I put in for ASE or warmup (anywhere from 100 -> 200%), the idle PW wouldn't change at all, and neither did the startup behaviour. It really seemed like the enrichments were just being ignored.

I'm not sure what or why, but I did upgrade my firmware to 029i or j around the same time that all this started happening. It's been a few months so I'm a little fuzzy on what happened exactly when. Either there was something wrong with it, or maybe my download goofed up or something. Tonite I upgraded to the current 029q2 code, double-checked my MSQ file to make sure nothing changed (it didn't), and gave it a go. It started right up and idled solid at the fast idle just like it should.

Repeated starts all worked fine as well. I did tweak the ASE and warmups again and this time it did seem to respond immediately to my changes. So for now, I'm going to chalk it up to the firmware version or maybe a load failure.

thanks
--Dan

Hey, it's good to hear you got it sorted out!

Sorry but my advice on ASE is completely wrong as I found out today, you had it correct. I remember James said there were serious issues with 029i so you're probably right in saying it was the firmware.

Ian.