hot restart issues

97chrysler · Post by **97chrysler** » Thu May 11, 2006 7:00 am

Starts great in the cold, but once warmed up... it will not fire without touching the gas - Sometimes, part throttle will touch it off, and sometimes you'll be there for awhile with it floored - I have monkeed with the startup enrichment to no avail - Where to go next?

Adam
MSnSe v3
029q2

Mike Simard · Post by **Mike Simard** » Thu May 11, 2006 7:19 am

It may not apply to you but my car would only start when warm with some afterstart enrichment, a fairly high percentage for very few engine cycles, for us MSII users, ASE at 160 degrees wasn't allowed until the new 2.54 and up beta versions. Before that I had to use a high cranking pulsewidth for the egine to catch but that would put it on the verge of flooding, I just needed some enrichment to make it from about 500 rpm up to idle and no more.

Bernard Fife · Post by **Bernard Fife** » Thu May 11, 2006 8:30 am

Adam,

In addition to what Mike says, you may have to experiment with your hot cranking pulse width. Typically people make this too long, but it is possible to make it too short.

Lance.

97chrysler · Post by **97chrysler** » Thu May 11, 2006 10:57 am

lance wrote:Adam,

In addition to what Mike says, you may have to experiment with your hot cranking pulse width. Typically people make this too long, but it is possible to make it too short.

Lance.

I noticed while cranking, the green box on my ve table jumps up to 90-100kpa (atmos) - Does it pull those values to calc fuel during cranking? - For cranking pulse addition, does it add to those above mentioned values? - I think it is flooding out - If I put the value to zero in the cranking pw window, will it just not fire at all then during cranking at the referenced temps???

Adam

Bernard Fife · Post by **Bernard Fife** » Thu May 11, 2006 11:36 am

Adam,

During cranking, only the hot and cold cranking pulsewidths (scaled by the coolant temp.) are used, and the amount is injected from each injector at each ignition event.

MAP and various other normal fuelling factors, like the IAT and VE table, do not enter into it at all (while cranking).

Lance.

mops · Post by **mops** » Sun May 14, 2006 2:45 pm

Lance, Can you please justify exacly what happens on cranking please ?

I have been troubleshooting my cranking issues, and i get some better results once i incerased cranking pulsewidths.

My confusion is because:

1. Megamanual states that cranking pulsewidths are used only while cranking. I interpret that when rpm's are under cranking rpm treshold (my setting is default setting, which is 300rpm), starting pulsewidth is used, while as soon as rpm's exceed cranking rpm VE table is used for fuel calculations.

2. By analyzing logs (chek out the screenshot and attached log), it appears that cranking pulsewidth is used abouve 300rpm's, in fact all the way to 800rpm (which is my target idle, but i can never tune it right, but thats whole another thread candidate). Moreover Gwarm shoots up to 150% durning startup and the gradualy decays. CTS is showing constant value. Howcome ?

Is that normal behaviour ? or am I just being dum ?

Thanks in advance.

Bernard Fife · Post by **Bernard Fife** » Sun May 14, 2006 3:07 pm

Can you please justify exacly what happens on cranking please ?

mops,

I don't know if I can justify it, but I can try to explain it!

Megamanual states that cranking pulsewidths are used only while cranking. I interpret that when rpm's are under cranking rpm treshold (my setting is default setting, which is 300rpm), starting pulsewidth is used, while as soon as rpm's exceed cranking rpm VE table is used for fuel calculations.

Yes, that is the way it is supposed to work, at least for MS-II and the standard B&G code for MS-I.

In your log, the time interval between the first rpm above 300 (544) and the pulse width rising is just 35.997 - 35.896 = 0.101 seconds. It's possible that the non-synchronous nature of the datalog (values are not grabbed 'all at once', so one or more lines in a datalog do not necessarily represent the exact same operating conditions).

So there may well be a problem, but it's hard to tell from the log. I would do a few things:

- reload the code,
- check the setting to make sure the cranking speed hasn't been affected (if it was mine, I'd recreate the settings by hand, using exported tables and pounding the rest of the parameters in) to make sure the settings file is not corrupt.

I'd also check this thread: http://www.msefi.com/viewtopic.php?t=17892 to guard against any potential comm issues.

Gwarm includes the afterstart enrichment - at least in the test I just did on the bench - that would explain the Gwarm values in your datalog.

Lance.

mops · Post by **mops** » Sun May 14, 2006 3:27 pm

Thanks heaps lance - it really clarifies things a bit.

I tried to do a burst datalog, but I dont know how to set the burst datalog feature to read from COM4 - it always wants to read from COM1 (which I dont use...)