LS7 Throttle/Idle Control?

[4wheels]

I've been looking but I don't see that the LS7 E38 ECM has the same options for "Throttle Follower" and "Throttle Cracker". Is there a similar function on these ECM's that have an ECT?

[GMPX]

Not that we have found, not to say that it's not in there though.

[mowton]

I've been looking but I don't see that the LS7 E38 ECM has the same options for "Throttle Follower" and "Throttle Cracker". Is there a similar function on these ECM's that have an ECT?

Better late than never...........

Min Idle Airflow acts like the older Follower, but not sure about the Cracker.

Ed M

[swingtan]

Actually,

E38 - "B1829: Min Idle Airflow" acts like
LS1 - "B4307: Idle Desired Airflow".


For the E38, "cracker" and "follower" are controlled under "Idle - Correction" and there are a few PID's that can be used.

Generally speaking.....


B1844: Idle Integral Step Size - acts as a sort term airflow correction and is used to both add and remove airflow. The trick to it is to read the graph as "required correction amount" not as an "error amount". For example, higher values in the "-ve" 'Idle RPM Error' area will remove "more" airflow. Seems back the front, but that's how it works for me.

B1845: Idle Proportional Step Size - acts more as a long term correction to add and remove air flow. So it is effected by the Integral Step size.


In my calibration ( 12607217 ) I get an integral setting for "Transient" modes and can add more airflow to act like throttle follower. Later OS's don;t have this setting so I'm not sure how they simulate "follower". Perhaps the "Coastdown" table is used for both, as they would be similar in operation.

Simon.

[mowton]

Actually,

E38 - "B1829: Min Idle Airflow" acts like
LS1 - "B4307: Idle Desired Airflow".


For the E38, "cracker" and "follower" are controlled under "Idle - Correction" and there are a few PID's that can be used.

Generally speaking.....


B1844: Idle Integral Step Size - acts as a sort term airflow correction and is used to both add and remove airflow. The trick to it is to read the graph as "required correction amount" not as an "error amount". For example, higher values in the "-ve" 'Idle RPM Error' area will remove "more" airflow. Seems back the front, but that's how it works for me.

B1845: Idle Proportional Step Size - acts more as a long term correction to add and remove air flow. So it is effected by the Integral Step size.


In my calibration ( 12607217 ) I get an integral setting for "Transient" modes and can add more airflow to act like throttle follower. Later OS's don;t have this setting so I'm not sure how they simulate "follower". Perhaps the "Coastdown" table is used for both, as they would be similar in operation.

Simon.

New to EFILive's parameters and nomenclatures (even newer to E38's :grin:)....HPTuners guy. I am learning to tune with EFILIve as my buddies shop uses it exclusively.

My assumption was based on the LS1 Follower parameters allowed a means for "slowing" the drop from high RPM's to idle (mechanical dashpot) at pedal relase or clutch depress. B1829 seemed a way to control the AF as RPM's dropped as well.

I can see the tie between B1844 and 1845 (same as HPTuners Adaptive idle airflow startegies) but assumed those to be a real-time adjustment which may or maynot be able to handle a sharp drop from quick high RPM/Airflow transients. Coastdown does sound like the Follower approach. Will look into that. B4307 being referenced to ECT and Min Idle Airflow referenced to RPM didn't allow a direct connect in my feeble brain.

Thanks for the input.

Ed M

[swingtan]

Think of B1829 as a hard limit "target" for minimum air flow. It sets a target for the minimum amount of commanded air flow and is referenced against RPM. So while it can help with controling the deceleration of the motor, it doesn't really act as a "follower" for the throttle.

The "Follower" acts like an accelerator "booster". It adds additional airflow on "Throttle opening" to make the car feel like it's getting off the line easier. It then reduces the amount of additional air to "0" for cruising.

The speed at which B1844 and B1845 react, is dialed in to the values used in the tables, especially for B1844. Large values result in faster response, but go to big and you get over correction. As with most settings, it's a balancing act that needs time and patience.

Simon.

[joecar]

mowton, welcome to EFILive...:cheers: