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tjts1 · 08-09-2011, 07:41 PM

Rather than describe DFCO I can show you how it works on my car. Below is a screen shot from a megasquirt datalog.
At the top is RPM, TP is throttle position sensor angle, PW is injector pulse width in milliseconds, and at the bottom is air fuel ratio between 10-20 afr.

I took my foot off the gas around 2100rpm. After the TPS closed to below 0.4% it waits 1/2 second before it shuts off the injectors. There is about a second delay between the moment the injectors shut off and the WBO2 sensor recognizes a change in the AFR. I coast down to 1200rpm when the injectors kicked back in. You can see a 2 second delay between the injectors turning back on and any AFR change. Total DFCO time was 15 seconds on a slight down hill from ~30mph to a stop light. You can see where I applied the brake initially when the RPM line bends downward then increased brake pressure before coming to a stop. The recording was done a while a go before I had idle control really nailed down. The RPM is a lot more stable now when I press in the clutch without all the big swings. You can see a quick PW blip to zero when idle RPM jump up above the DFCO trigger point. This is the type of thing you look for to fine tune MS for daily driving.
cheers

08-09-2011, 07:41 PM	#17 (permalink)
tjts1 Banned Join Date: Feb 2008 Location: california Posts: 1,329 Thanks: 24 Thanked 161 Times in 107 Posts	Rather than describe DFCO I can show you how it works on my car. Below is a screen shot from a megasquirt datalog. At the top is RPM, TP is throttle position sensor angle, PW is injector pulse width in milliseconds, and at the bottom is air fuel ratio between 10-20 afr. I took my foot off the gas around 2100rpm. After the TPS closed to below 0.4% it waits 1/2 second before it shuts off the injectors. There is about a second delay between the moment the injectors shut off and the WBO2 sensor recognizes a change in the AFR. I coast down to 1200rpm when the injectors kicked back in. You can see a 2 second delay between the injectors turning back on and any AFR change. Total DFCO time was 15 seconds on a slight down hill from ~30mph to a stop light. You can see where I applied the brake initially when the RPM line bends downward then increased brake pressure before coming to a stop. The recording was done a while a go before I had idle control really nailed down. The RPM is a lot more stable now when I press in the clutch without all the big swings. You can see a quick PW blip to zero when idle RPM jump up above the DFCO trigger point. This is the type of thing you look for to fine tune MS for daily driving. cheers Last edited by tjts1; 08-09-2011 at 08:01 PM..