Crank Tuning

Holden/Delco Tuning. ALDL, OBD 1.5. Circa 1989 to 2004.
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Crank Tuning

Postby h4x0r » Sun Sep 13, 2020 5:01 pm

I'm really struggling to get my 304 to start when its hot around 90 degrees, so I setup a graph to monitor cranking.

crank2.PNG


I'm using siemens 60lb injectors.

I really don't understand the difference between the First stage and Second Stage base pulse width tables. Why are there 2 tables?

It appears that when my car is hot it likes to start around 2 mSec BPW. What is causing the BPW to increase to 3.91 as pictured in the graph? When it increases the fuel like this it really struggles to start.

What other variables am I missing?

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Re: Crank Tuning

Postby vlad01 » Sun Sep 13, 2020 5:08 pm

ah this got me too once.

check the parameter called " min crank BPW" default is 6 something ms and overrides any of the setting in the above tables you are playing with.

I would try 1-2ms and then your tables should work.


I would divide both tables by the difference in injector size from old to new. So old being about 19lb and new 60lb. 60/19=3.16~ so divide the whole table by 3.16. That will make sure the cranking fuel injected is the same as it was when everything was stock. Most of the time the cranking fuel doesn't change too much with mods like cam etc... You can adjust it from there anyway.

My engine with mods and 39lb injectors was just the straight division of the tables plus setting the "min crank BPW" to less than or equal to the smallest value from the craning tables.
Last edited by vlad01 on Sun Sep 13, 2020 5:23 pm, edited 3 times in total.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Crank Tuning

Postby vlad01 » Sun Sep 13, 2020 5:12 pm

Min-crank.PNG
Min-crank.PNG (38.57 KiB) Viewed 199 times
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Crank Tuning

Postby h4x0r » Sun Sep 13, 2020 9:42 pm

I did think of the "Minimum crank BPW" and I had already set it to 1 Msec

Does anybody know how crank fueling works? Why is there a first stage and a second stage base pulse width?

crank3.PNG


Here you can see 3 cranks in a row where BPW stays at 1.95 and it starts immediately. I don't understand why it sometimes jumps up to 3.91

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Re: Crank Tuning

Postby VX L67 Getrag » Mon Sep 14, 2020 10:26 am

I think from memory they use the 2nd table if it failed firing on the first attempt of cranking.

If you adjusted the way mentioned above to get in the ball park for bigger injectors & it's not firing in that range & not fouling(flooding) plugs add more in that area till you get it firing right!

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Re: Crank Tuning

Postby h4x0r » Tue Sep 15, 2020 2:33 pm

Guess I need to spend more time troubleshooting it. The only reference to 3.91 mS is in the second stage crank bpw at 56 deg temp but the logs and temp gauge clearly show its above 90 deg.

I just can't see any obvious logic to crank bpw.

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Re: Crank Tuning

Postby vlad01 » Tue Sep 15, 2020 3:44 pm

I checked mine which is 40lb injector. My lowest on 1st stage is about 10ms and 4.8ms on the 2nd stage so you should be about 3ms for the min for 1st stage and 2.5ms for 2nd stage based on the V8 tables. It should start on what you are logging I would think.

Does it start when you keep the throttle open 100% while cranking?
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Crank Tuning

Postby vlad01 » Tue Sep 15, 2020 4:08 pm

There is also crank decay step size. That is 4ms on the stock v8 tune. I have my v6 one set to 2ms, I don't remember doing it but it seems to had worked.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Crank Tuning

Postby h4x0r » Tue Sep 15, 2020 6:30 pm

vlad01 wrote:There is also crank decay step size. That is 4ms on the stock v8 tune. I have my v6 one set to 2ms, I don't remember doing it but it seems to had worked.


I had been pumping the throttle to get it to start when it was hot for the last year. Now I'm trying to fix it properly. Yeah I had mine set to 2ms and just set it back to 4ms. But I don't understand what that setting does...

I might understand the 2 tables now. I think it starts with the first table until it reaches the Number of reference pulses before secondary crank fuel:
crank4.PNG
crank4.PNG (25.09 KiB) Viewed 90 times


factory is 41 pules for the v8. Juding by the logs thats only a few seconds. I'm going to set it to max and see if it gives me more time to tune the first crank fuel table.

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Re: Crank Tuning

Postby vlad01 » Tue Sep 15, 2020 7:28 pm

odd, mine kept drowning the engine until I set the min BPW and decay step size smaller than my table's min values. Then it started first go every time.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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