Saturday, December 31, 2005

.. Ok so I got bored

While planning the next set of changes I decided to try and chase down some minor idle issues. Like RPM dipping at low speed when in neutral.
After some reading on EFILIVE forums for idle transition and idle tuning I made a few maps and pids and went logging from startup to full operating temp.
I pasted the changes into the Desired Air Flow tables and things are now much smoother. I think the 1.8 rockers might have thrown the stock idle table out a little. Good stuff, Im now prepared for some cam idle tuning next year come cam install time.

That was too easy, so I decided to look further into suggestions that you can get a similar effect to a "pump shot" by messing with the throttle follower tables. This handles the transition from idle to running airflow. Factory default is to trickle changes in until throttle position sensor (TPS) is at 13% at which time it is increased 6 fold! There will be some interpolation, but I decided to make it more linear, so scaled the roll in from 3% TPS and set the mulitplier at 1200 to match 1600 RPM lead in. The car now launches off much more confidently without the delay from idle requiring 15%+ TPS to make it do anything. Another sucessful series of tuning actions and no observable ill effects.

I will be logging a lot come tuesday as Im off up North again so will check to see if this additional airflow has affected my AFR readings and hence VE table. I doubt it, as its only put in on TPS +ve delta changes, then decayed out.

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