FG barra TB lockdown

[Tyler06]

Have got an FG xr6t engine in a GQ patrol. Car stalls on gearing down coming to a stop. On logging the run the PCM is going in to lockdown mode and shutting the throttle body to stall it. Any suggestions?

[Tyler06]

Sry heres a log... with new tune and it doesnt appear to be same prob but still stalling when coming to a stop in low gear.fggqstallissue.hpl

[lukearmstrong1990]

you have no speed input into the PCM.

it usually uses "idle dashpot minimum" and "idle dashpot predisposition" tables to control airflow when the car is coming to a stop.

they will not work here as the car always thinks its idling. my suggestion would be to add some airflow into the 550/600/650 cells in idle airflow for both park and drive.

Engine>idle>airflow will get you to the tables mentioned above

with your 700rpm idle it will ask for some more air if the RPM dips.

it would also pay to under Engine>idle>general set the enable rpm error to 250 or 300rpm and set the disable rpm to 5

when you're coming to a stop the PCM doesn't know that so is trying to reduce the RPM to your commanded 700rpm idle because it doesn't know the car is moving. then once it pulls it down it has to correct it which you can see it try to do in the log throwing timing in. the adaptive idle is great to work in a small window of MAP say 30-35KPA. but without speed input it now has to work over a window of say 12-35KPA.

or your other option is set the minimum VSS value under Engine>idle>general to 0rpm and then use the dashpot tables to control idle airflow.

you could also try giving it a bit of fuel down low at 550/650 rpm and see if that is enough to stop it. go to Engine>airflow>speed density and get the "MAP per airmass IMRC closed" table. grab the entire 550/650 rpm columns for all cam angles and multiply it by .9 (adding 10% of fuel) it might be just enough.