IDLE

[Brendon Frame]

Am running a G3 with closed loop idle to fix a problem with aircon and eng fan steps. I'm still finding that the idle as the car is warming up is erratic. Ie. it goes high and then gradually drops but not to the same values each time. I know things were better with open loop, but the aircon step was really bad. This is better than it was but still not very accurate for closed loop. Is this fixed in the latest release of code 1.4 (the G2 is mentioned). Also the eng fan step only works with aircon on, otherwise it does nothing regardless of eng temp. Any ideas? Also during warmup, ie below 50C the revs going from driving to idle stay high and then very slowly decrease.ie 4-6secs. Is this part of the differential/proportional settings.

[ashesman]

There are some fixes for air con step and fan step in the latest firmware release.  They apply to G2's running open loop idle, they have always worked for closed loop. 

Now, as far as the inconsistency with your idle speed goes, if you are having trouble with closed loop control it will be a tuning problem.  Closed loop idle is not something that can just be turned on and will work.  It must be set up correctly which is usually quite tricky. 

There is a built in delay when engine speed comes back to idle where the RPM will be stepped down in two steps over a fixed time period to soften the return to idle and prevent undershoot and stalling.

Proportional gain controls how hard the ECU tries to correct variations between the desired engine speed and actual engine speed.  Differential gain sets how much the ECU responds to sudden load changes, such as air con being turned on.

Are you using a speed input.  Are you using stepper or solenoid idle?  What value is your dead band?  Have you read through the entire idle section of the PCLink help?

[Brendon Frame]

My open loop idle was average to alright but was a lot closer to the mark than the closed loop is when the engine is warming up. I have followed the instructions which say to setup open and then check the actual output to the solenoid to get the closed loop values. This seems to be fine when the engine is running at around the the 90C mark. The problem I have is that when aircon is used the idle doesn't stay in the same place. I also find that if I blip the throttle that will sometimes change the idle so it comes back down to where I have told it to be. No speed input, solenoid 2 wire, deadband is 2kpa otherwise (for accel) and 4C for the eng fans. I don't understand why the idle is to funny while warming as this used to be fine when I used open loop. The only reason I went to closed loop for idle was due to Simon telling me that the bug for the aircon input 'should' be fixed when I used closed loop. This is still an issue as mentioned above, which is a little annoying when sitting at the lights and the car is revving away and you turn the air off and on again and it comes right. Also the eng fan adjustment does nothing unless the aircon switch is on. I will try the 1.40 firmware and see if anything is fixed wrt the issues above. Is there a way I can adjust the time the idle takes to return to proper idle when warming up other than spending lots of time playing with the gains?

[ashesman]

The fix was in the 1.4.0 firmware only...  The time to return to idle is fixed.  You will have to set up different gains for different temperatures.  Noone ever said that ISC control would be easy to set up, but can be made to get stable idle at all temperatures.  It is also important that AFR and ignition timing remain stable as idle load alters...