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Old 12-31-2014, 11:47 PM   #1
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Default MSM0405 Starting Kickback

04MSM with newly installed MSPro. Base tune. OE injectors. Timing verified with timing light.

When the engine is completely cold in my 35degF garage it takes a few seconds to start, but does so without incident.

After the engine has been warmed a few minutes (coolant temp about 100degF) and shut off, upon restart it will kick back and stall or almost stall the starter. The timing is about 15 deg BTDC during starting.

Is there a set of timing parameters available for adjustment or are they only controlled by the timing table?

What's the best way to rectify this issue?

Thanks,
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Old 01-01-2015, 06:02 AM   #2
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It can be that the idle valve PWM is set too high at that temperature. I found that I got kick-back when cranking kPa was running 98, but stopped when I lowered PWM and got cranking kPa of 90. Changing timing did not help.

There is a separate setting for just cranking advance. On the same screen as setting of trigger wheel, IIRC. Again, I don't think that is your issue.
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Old 01-01-2015, 10:29 AM   #3
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welp its either fuel or timing. if you are sure timing is spot on (mechanical AND commanded btw) then you need to look closer at fuel, cause flooding can cause that too and sometimes too lean will cause the car not to start and flood at the same time too. if that makes sense
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Old 01-01-2015, 12:17 PM   #4
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Originally Posted by 18psi View Post
welp its either fuel or timing. if you are sure timing is spot on (mechanical AND commanded btw) then you need to look closer at fuel, cause flooding can cause that too and sometimes too lean will cause the car not to start and flood at the same time too. if that makes sense
Timing set to constant 10 deg BTDC is verified. Commanded was not verified with timing light. And no, lean flooding does not make sense unless it's so damn cold there are no vapors to ignite. In any case, it does not appear to be flooding.

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Originally Posted by DNMakinson View Post
It can be that the idle valve PWM is set too high at that temperature. I found that I got kick-back when cranking kPa was running 98, but stopped when I lowered PWM and got cranking kPa of 90. Changing timing did not help.

There is a separate setting for just cranking advance. On the same screen as setting of trigger wheel, IIRC. Again, I don't think that is your issue.
I forgot to mention in my original post: I got the kickback when I reset the timing to "use table" after verifying the fixed 10 deg with a timing light. I changed it back to 10 deg fixed and did not get kickback. That's not a conclusive indictment because it does not happen on every start and my sample size is low.

I found the setting for cranking advance. Thanks for the help. Do you know if the fixed advance overrides the cranking advance?

I will probably go down the timing route first since that makes more sense to me. Hand cranked engines taught me that timing made the difference between success and getting knocked on my ****.

Thanks,
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Old 01-01-2015, 12:20 PM   #5
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commanded meaning what does your timing table dictate at sub 1k and 35-100kpa since that is where it's looking when you're cranking.

cranking advance plays into that too, but I forget if it takes priority or what
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Old 01-01-2015, 12:23 PM   #6
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lean flooding is when you're injecting not enough fuel to start, but you keep injecting it so it pools up and you end up with a crappy startup. I've actually experienced this, and it does sometimes result in kickback ( had this happen).

but sounds like that's not your issue. investigating timing is probably a better approach.
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Old 01-01-2015, 12:32 PM   #7
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Cranking advance overrides your timing table while you're in the "cranking mode." You are in the cranking mode until your RPM exceeds the "cranking RPM" setting. At that point, your timing table takes over. You can verify this by watching your spark timing gauge while cranking the engine. You'll notice that it will start at your cranking advance setting and then quickly transition to your table setting during the starting procedure. I have my cranking advance set to 5 degrees ATDC because I too have been knocked on my butt trying to prop an aircraft. LOL.

Not sure whether the fixed angle setting (for setting timing with a light) overrides all or only the table advance. But that's a maintenance procedure so not really germane.

I get this sometimes too. It usually indicates that my battery charge is weak. A warmed up engine generates more compression and a weak battery has a hard time overcoming that increased compression.
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Old 01-01-2015, 03:23 PM   #8
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Realize also that the timing that is used, after start - to - run occurs, is the advance in the 80 kPa range, not the idle range, because as the car starts, those are the cells that are active.
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Old 01-02-2015, 12:56 AM   #9
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Thanks!
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