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hymey
May 25th, 2008, 11:49 PM
Hi guys,

Still experience issues starting mafless. The problem has become worse with the updated cal files. Operating system is
12619078. It is a Jan 08 build VE. I have even gone to the extent of flashing swingtans cranking maps and airflow data in aswell as open loop tables. It didn't help. The throttle will open and close very quickly causing lean spikes. We have tried increasing and reducing airflow and fueling. The car may start fine one day, the next day the electronic throttle will have "spasms" but eventually settle down, 50% of the time it stalls. I can then try and restart it as many times possible but it wont start. But heres the catch. I reflash the pcm with the EXACT tune and it starts perfect and will do so for a few starts then it will play up again. I thought it was something I'd missed and if it wasn't for Simons help I would have pulled my hair out by now. But not even his expert advice can solve the issue. 3372

It is like it wants more airflow at cranking. I command the airflow very high at cranking and it settles down nicely but then for a few seconds it plays up and stalls. I have tried higher and lower airflows it doesn't matter. I have used the latest cal files in cranking to help so the issue. Also used the new file that commands the car to go from start up to idle in a specified time but it did not help. The log above is a start up log. My w/b was still warming up at the time so it didn't read but you can see commanded fuel there. It goes terribly lean when the airflow increases.

I see the new B2005 setting there in dynamics. That will be useful in gearchanges with manuals as they have a lean spot on fast throttle movement when mafless. Lifting this to 5% will be worth trying than fine adjusting from there.

Hope you guys can help out. The strange part is I have tuned a friends VE mafless and his car is fine? I think it is airflow related. Do we require a patch?

Cheers

Joel

Delco
May 26th, 2008, 11:48 AM
Hi guys,

Still experience issues starting mafless. The problem has become worse with the updated cal files. Operating system is
12619078. It is a Jan 08 build VE. I have even gone to the extent of flashing swingtans cranking maps and airflow data in aswell as open loop tables. It didn't help. The throttle will open and close very quickly causing lean spikes. We have tried increasing and reducing airflow and fueling. The car may start fine one day, the next day the electronic throttle will have "spasms" but eventually settle down, 50% of the time it stalls. I can then try and restart it as many times possible but it wont start. But heres the catch. I reflash the pcm with the EXACT tune and it starts perfect and will do so for a few starts then it will play up again. I thought it was something I'd missed and if it wasn't for Simons help I would have pulled my hair out by now. But not even his expert advice can solve the issue. 3372

It is like it wants more airflow at cranking. I command the airflow very high at cranking and it settles down nicely but then for a few seconds it plays up and stalls. I have tried higher and lower airflows it doesn't matter. I have used the latest cal files in cranking to help so the issue. Also used the new file that commands the car to go from start up to idle in a specified time but it did not help. The log above is a start up log. My w/b was still warming up at the time so it didn't read but you can see commanded fuel there. It goes terribly lean when the airflow increases.

I see the new B2005 setting there in dynamics. That will be useful in gearchanges with manuals as they have a lean spot on fast throttle movement when mafless. Lifting this to 5% will be worth trying than fine adjusting from there.

Hope you guys can help out. The strange part is I have tuned a friends VE mafless and his car is fine? I think it is airflow related. Do we require a patch?

Cheers

Joel


No patch required , you have a tuning issue which is apparent from the fact it is perfect until it learns then it goes to crap.

If the settings for airflow are correct then minimal learing is required and the tune doesnt change.

Concentrate on your airflows and getting the learnt values to as close to zero as possible.

hymey
May 26th, 2008, 12:06 PM
Thanks Dan,

Yeah it is perfect until it learns. How do I measure if it's learning. By logging dynamic airflow vs actual airflow?

Cheers