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Old 11-06-2009, 07:47 PM   #1
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Default Cranking settings calculator

I've now dialled in my warm and hot start cranking settings, they are pretty much OEM style which is pleasing. The only issue is that it's now getting quite cold in the UK with morning temps of around 8-10*C and yet after a few weeks of proper cold start tuning attempts, I still have issues getting the engine to catch properly on the first attempt.
I've gone through the cold start temp areas of 4*C and 16*C regions a few times increasing and decreasing by 0.2ms and I just can't get it to start as well as my hot start settings.

Is there a way to calculate backwards from my warm/hot start PWs to give me some accurate cold start figures?

My table is currently this: (Stock injectors, req fuel of 13.2)

-40C - 8.8
-29C - 8.3
-18C - 7.8
-7C - 7.3
4C - 5.8
16C - 5.6
27C - 5.6
38C - 4.5
54C - 3.6
71C - 3.1

Prime pump = Prime pulse
Fire priming pulse = after 2 secs
Priming PW source = priming table
Cranking pulse width temps = CLT only

The fact I have to wait for my LC-1 to heat up for approx 25 secs might not be helping to cold start as the the MS has already fired it's prime pulse some 23 seconds previously.

Cheers,
Craig
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Old 11-06-2009, 08:00 PM   #2
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Does your fuel rail operate at a static 60psi or is it a returnless setup like most?
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Old 11-06-2009, 09:09 PM   #3
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AFAIK it's static 60psi, although I've never had a pressure gauge on it. I'm under the impression that all NBs use this revised setup?
My current PW settings would certainly suggest so given the low PW values in the hotter regions of the table. From most of my research it seems most NA owners run similar PW values when using 440/550cc injectors.

Oh and my fuel pump is stock.
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Old 11-09-2009, 06:19 PM   #4
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So after reading up on this thread, it seems dwell settings also play a part in improving the cold start.
My dwell is currently set to:
Cranking - 8.0ms
Running - 3.5ms
Min Discharge period - 1.0ms

Some maps I've seen are set to 5.5, 4.4, 0.5 and also 8.0, 4.3 and 1.0 respectively.

Is my running time too low hence the poor catching of the engine?

Also has anyone pulled the code from the various OEM ECUs? Surely there is some pretty simple maths involved? i.e. dwell, IAT,CLT, injector firing type = cranking PW figure of.... (that's a hypothetical 11ms )

My car sounds EXACTLY like this http://tim.kent.googlepages.com/2009...ning-start.m4a It takes me 3 or 4 cranking sessions of around 2 seconds each before it finally catches since the recent temps have dropped so low. I even have that 'hydrolocking' sound which would make you think you're cranking too much fuel! That can't be so as the engine only starts to make that sound after excessive cranking attemps. I guess it could be due to the previous failed cranking sessions adding more and more unburnt fuel? I'm just clutching at straws though?
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Old 11-10-2009, 03:58 AM   #5
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all Euro NB's still have the old style setup with fpr.
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Old 11-10-2009, 09:58 AM   #6
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If that's the case then I'd try a table like this:

8.9
8.8
8.3
7.8
7.7
7.5
6.3
4.8
3.6
3.1

because you have to crank so much it sounds like you don't have enough fuel...
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Old 11-10-2009, 10:38 AM   #7
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Mine is a 1995 NA, so I can't help with your settings. But for some reason I also get the hydrolock / timing too far advanced thing when starting. Not all the time, maybe once in 10. Otherwise it starts fine. It seems to have gotten worst since I went to the Hires code.
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Old 11-10-2009, 10:40 AM   #8
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then tune your cranking pulse widths table...
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Old 11-10-2009, 11:17 AM   #9
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I was thinking it was some sort of ignition thing. I searched and have seen other people mention this problem, but no solutions. The cranking PW's have been tuned, and the car starts great at any ambient temp. Adjusting "cranking advance" seems to help, but if I run it way down to 2-4 degrees I have to spin the starter quite a bit before it catches. At 10 or so I have a factory like start. Most of the time, once in a while I get that occasional drag like the timing is way advanced. Maybe my starter is going bad?

What I was trying to point out is that I think there may be two separate issues here. Not sure if the hard start I'm occasionally getting is due to cranking PW.
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Old 11-11-2009, 05:39 AM   #10
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Cheers Braineack.

I changed the colder temp PWs and it started up first time from cold this morning. I thought I was so close too, just goes to show I was near enough 2ms out!
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