This is DBW idle, I tuned idle manually with ignition timing and airflow to begin, then configured the PIDs, and it works well.
However, sometimes I see quite a high rate on the TPS (as high as 70-80%) from the idle airflow PID, which triggers an acceleration enrichment and the engine picks up RPM by itself.
I know I can increase the acceleration enrichment threshold %, but this then effects enrichment at slower throttle openings - I had this set to 20% before, now I have to set it at 90-100% to stop the idle airflow PID triggering enrichment.
This engine has a large throttle body for its displacement (OEM). Should I be seeing such high rates on the TPS or is the configuration wrong? It idles fine and i normally only have between -1/+1% airflow correction.
My thought - is it possible to disable acceleration enrichment if the requested TPS change is from the idle strategy - but still operate if the requested TPS change is from the PPS/DBW strategy?
I know there is an additional correction table being added for the acceleration enrichment, which may somewhat help with this, but if acceleration wasnt even considered in the idle strategy it may stop it happening completely?
Question…why u think ACC is not needed in idle but in the same situation out of idle?
ACC is independed of idle.
If u need the enrichment out of idle…u will also need it in idle in the same situation. If u dont need it in idle then u also dont need it out of idle in the same situation.
So deactivating it in idle actually makes no sense.
I expirienced then same as u…and thought it would be good to deactivate it in idle…but then i realized that i actually don’t need ACC with low rates…my threshold was set way to low and enrichments too high and i think in ur case it is the same.
Of course it is needed in idle state, for when you hit the pedal, I didnt mention about deactivating it…
My suggestion was to NOT apply acc enrichment IF the TPS change is requested by the idle strategy itself, via the idle airflow PID, as per the above screenshot ,but operate as normal if the TPS change is requested by the DBW/PPS
My accel performed well when “in use” throughout the RPM range. However I have now lost some at the slower rate end due to increasing the threshold %.
This started as I was trying to work out why my idle randomly just increases when it is just sat there for a period of time, as per the screenshot, which led me to finding the acc enrich was being applied as the idle airflow PID changed the TPS.
Unless there is something wrong with my set up and I shouldn’t be seeing rates that high from the idle airflow PID?
I understand what u mean.
What i want to say is, that the source of the TPS change, which results in the rate, doesn’t matter. If it is the idle PID, the pedal or something else. If the ACC is needed in the one situation, it is also needed in the other.
Anyhow…i think u are right…u should not see that high rates comeing from the PID and something in ur idle settings is reacting too strong.
