Cold Cranking Questions (DIYPNP, MSII)
 

I am driving with the DIYPNP for the first time in cold weather (20-30F) and cold starts are longer than I would like. I have read countless posts on the topic, but still have a few questions:

1) Cranking Spark Angle - What is a good value here? Mine is set to 12 (no idea why) and I am thinking this is probably way to high.

2) Priming Pulse Width - My graph goes from 9.0 PW at -20F to 2.0 PW at 200F. I am guessing that my numbers are way too high. What are good values here?

3) Cranking Pulsewidth - The MS calculates the actual PW as "Cranking PW % * Ref Fuel", so these values should be faily universal across Miatas, correct? So, what are good values here for cold temps (0F - 40F)?

Thanks!

1. I use 8*
2. Different for every car and every injector
3. see #2

This is not hard, it requires though and you can easily do it in a few minutes.

I will try dropping my cranking angle to 8 and see what difference that makes.

I agree that 2) would vary by car, but I am just looking for ball park values since ths is not a critical item (such as a VE table).

Regarding 3) Cranking Pulsewidth - since this is a % of req fuel, wouldn't this be fairly universal (i.e. MS would take into account engine size, injector characterics, etc.)?

I use like 15° cranking.


what basemap are you running off of? what injectors do you have?

Doh, thought I had my car info on my sig line, but that is on that other miata site.

I have '95 1.8, '99 head, with 420 CC injectors (RX8).

Base map was from MSPNP9495 and then converted to MSII when I upgraded to the DIYPNP.

Reducing cranking spark angle from 12 to 8 seems to have made a positive impact. Previously, the starter would hang up at times, as if the battery is weak. It would also stumble after catching and struggled to get to normal idle. It no longer hangs up, seems to spin faster (have not burned a log to check crank RPM), starts are quicker and it catches clean w/o stumble. Still room for improvement, but this is a definite improvement. The weather has been slightly warmer since I made this change, so this could be a false positive, time will tell.


Thanks!

Where is Cranking Spark Angle set? My '2000 exhibits same hard starts. Is it "Cranking Advance" under Basic Settings -> More Ignition Settings?

That is correct.

Wow. Mine is set at 6 now and the car coughs and sputters while trying to start. Usually takes at least a couple tries to start.

Should I move it to 8?

I don't think 8 is a magic number. In my case, I believe that I had too much spark advance, which is not likely the case for you (assuming your timing is set correctly). You can always make the change and give it a try.

I will burn a few logs this weekend with both 8 and 12 degrees of cranking spark advance to see if I can prove that the motor turns over faster while cranking with 8 than 12.

Sub'd for results. My cold starts are a little rough as well, even after fine tuning fuel.

I ran several tests tonight, over the course of several hours, with temps 29F to 35F. I feel that the car starts better with 8 degrees cranking spark vs 12, but logs don't really show a difference. However, I realized in this that I had also reduced the cranking dwell from 5 to 2.5 (Toyota COPS) before starting this thread (I caught this mistake when researching this topic). I reverted this back to 5, and when combined with 12 spark advance, the car does not start as well - and the log shows it. I assume the excessive dwell might cause the COPS to release the spark too soon.

Who knows, but my car is starting acceptably now in 30F temps with cranking spark at 8 and cranking dwell at 2.5.

okay, now after youve done little to solve the problem you can move onto to tuning your cranking pulse and finally get it to start correctly...

Both my Cranking Dwell and Crancking Advance are at 6. Time to change to 5 and 8 respectively?

Anything else important in those settings?

Temps hit 19F over night, so I went out to see if the Miata would start. The engine barely turned over (I think my batt is getting weak, came with the car ~5 years ago), but the car did start after a few seconds of very slow cranking, and then ran fine once started. She gets put away for the winter tomorrow, and the temps are warming over the w/e, so this may be the last really cold start for a very long time (I usually put the car away on Thanksgiving).

Am I the only one with their cranking advance set at 0?

I had mine set at zero and changed it to 8 based on what people were saying in this thread.

I need to spend some time cold-start tuning. It definitely cranks for way too long when it's cold. I'm pretty sure it just needs more fuel, but I haven't looked into it.

To resurrect this thread and, once again, beg for help...

My car (2000 with MS2) is a dedicated autocross car. It sits out there in the field and gets started once every week, sometimes every two weeks. Lately it's been almost impossible to start in the morning. The car cranks but doesn't catch at all. At first I was convinced that it's a crank sensor. 50K worth of hard living, why not. Change that. No result. The only way to actually start the car was to, get this, swap the stock ECU in. It would start immediately. Replacing ECU with MS2 after that, the car would start fine all day long. After some though we think that car doesn't get fuel to the engine initially.

Last time on advise of people smarter than myself I've turned the key to ON position for good 15-20 seconds before cranking. The car started with MS2 in, although not right away, but it started. So the no-fuel theory is a definite possibility, it just needs to be primed after not being driven. However, the car has not done this previously. Could it have been caused by above mentioned Cranking Advance change? Anything else to look at? Car's about 40 miles away so it's hard to deal with.

Thanks again, guys!

The car is still refusing to start in the morning after sitting for a while. Swapping stock ECU in starts it right up. Swapping back to MS2 after that - the car starts fine all day long.

Could someone please look at my current .msq file plus the one I originally got from my tuner and give any suggestions? One problem is that the project started in Celsius but tuning file I got from the dyno tune was in F. I might have screwed up the conversion somewhere. Specifically, I'm concerned with "Overrun fuel cut". It seems that the car was starting fine in the winter but is not getting any fuel in the summer.

Hep, please! Save the last of my hairs before I pull them out.

Anyone? Bueller?

When you first go out to the car and before cranking it, cycle the key from off to on position, wait two seconds, then turn off. Repeat 2 more times then try to crank it. If it cranks more easily, you need more fuel in your priming pulse and cranking pw settings.

If it is worse, next time after that, turn the key on then push the throttle flat on the floor and try to crank it. This will enable flood clear mode. If it cranks more easily you are getting too much fuel and need to reduce it.

Thanks, I'll try that!

Oddly enough, the car started OK before the race yesterday. Temperature was in low 60s in the morning, so I suspect my temperature theory to be correct. Any thought?

I've never really had to start my car in sub 40F weather. But i noticed that i needed WAY more fuel than i thought when i was first tuning cold start. I'm upwards of 200% below 55F, with a pretty steep warmup enrichment. Maybe that's a bandaid to keep it running but it works for me.

did you even tune your cranking pulsewidth for colder weather?

Brain, are you asking me or Erat? My tune is on the previous page. Any changes that I should make?

you. did you tune your tune for cold starts? or did it just not work and you were like, i guess ill post online without actually attempting to solve it myself and hopefully someone can hold my hand and tell me how to tune an aftermarket ecu?

Ummm... Firstly, my tune was done by my dyno guy. I am trying to learn the details of MS tuning but relied on his expertise. He's no longer there and I'm having several issues I'm asking about.

Secondly, the problem I'm describing, which is constant crancking with no start in damp 80F+ weather is not likely related to cold starts, although I may very well be wrong, that's what I'm asking here and I truly appreciate all the help i can get.

As a quick update, I just went to the car. The outside temp is 63F, it's dry. I did what Sixshooter suggested above, which is 3 quick On-Off cycles. The car started pretty easily. But again, it was trying to start even before this procedure. What I was describing above was different - the car would crank forever and not even try to catch.