Hello All,
Among the various little annoyances I have been diagnosing, one concern is the cold start performance of the car.
Behavior:
- Cold engine (overnight), start and drive the car.
- Throttle response is very slow.
- holding steady throttle (I.e. 20%), the car will not have a steady acceleration (surging).
- EXCEPTION to these symptoms is if I pass ~3250RPM.
- As the engine warms up, the behavior goes away.
Analysis:
Have a look at this log, I know its missing the actual Y-Axis values, but pay attention to the relationship between Accelerator pedal (APP) and ignition advance.
- Throttle is steady at ~20% +/- 1%
- At ~3250RPM, the ignition timing jumps from ~6-7° to 30°+.
- Coolant temperature is cold (~20C)
Ignition advance would definitely cause this behavior, and I am trying to understand how I can eliminate it.
This could be intentional behavior for emissions purposes, but the drivability is unacceptable.
I imagine VTCS delete has a lot to do with this, but I would like to hear some ideas.
Comparing ignition tables to "Stock" they are identical for the most part, but I cannot find any direct logic that would bring ignition timing to ~6-7°. Unless I am missing something, these would be tables not modifiable by AP.
Log is attached, but it is rather large to catch both cold and hot behavior.
Thanks in advance!
Among the various little annoyances I have been diagnosing, one concern is the cold start performance of the car.
Behavior:
- Cold engine (overnight), start and drive the car.
- Throttle response is very slow.
- holding steady throttle (I.e. 20%), the car will not have a steady acceleration (surging).
- EXCEPTION to these symptoms is if I pass ~3250RPM.
- As the engine warms up, the behavior goes away.
Analysis:
Have a look at this log, I know its missing the actual Y-Axis values, but pay attention to the relationship between Accelerator pedal (APP) and ignition advance.
- Throttle is steady at ~20% +/- 1%
- At ~3250RPM, the ignition timing jumps from ~6-7° to 30°+.
- Coolant temperature is cold (~20C)
Ignition advance would definitely cause this behavior, and I am trying to understand how I can eliminate it.
This could be intentional behavior for emissions purposes, but the drivability is unacceptable.
I imagine VTCS delete has a lot to do with this, but I would like to hear some ideas.
Comparing ignition tables to "Stock" they are identical for the most part, but I cannot find any direct logic that would bring ignition timing to ~6-7°. Unless I am missing something, these would be tables not modifiable by AP.
Log is attached, but it is rather large to catch both cold and hot behavior.
Thanks in advance!