MembersPage/GergelyLezsak/IdleControl (2005-08-29 12:00:31)

IAC

This is a 3-pin solenoid. Guess it is stock on motronic 1.3 systems for M20 engine.

Measurements I made on it: MembersPage/GergelyLezsak/IdleControl/Measure

Docs found about similar valve: MembersPage/GergelyLezsak/IdleControl/Docs

Pictures I made: MembersPage/GergelyLezsak/IdleControl/Pictures

Driver selection: MembersPage/GergelyLezsak/IdleControl/Driver

Firmware related: MembersPage/GergelyLezsak/IdleControl/Firmware


Actually we've got a hacked firmware to control it. Now the valve is moving smoothly but still has some instability in idle. It might be related to mechanical problems instead of configuration/control. (Not sure)


Configuration and other issues

PID config changes doesn't really alter the rude fluctuation of my idle. It changes in a ~160rpm range without characteristic period. [Here] is a datalog XLS from megatune, I've created a diagram into it also. Note that with fixed iac value the engine's idle is altering appr. the same way. (Maybe compression diff. between cylinders? I've a somewhat modified camshaft maybe with +30 degrees opening.)

Idle fluctuation usually happens (ie. not counting idle control characteristics etc.) if;

Turn engine crankshaft to angle, after top dead centre, where cylinder one inlet valve is fully open - and measure angle turned. fex. using degree wheel or circular length calculation (ie. same kind of way that descriped in 60-2 pulse wheel trigger angle) method.
  • How will I know the engine is at TDC, and the valve is open/closed?

Should check and correct it mechanically and injection parametrically wise and then look the pwmming.

Amount of ignition advance you are using in idle and near to idle ? around 20-23 degrees in this range. Ignition advance at idle might be bit on a 'high side', maybe engine needs over 20 deg. if compression ratio is much less than what it is in std. engine.