VEMS: the unstoppable pulsing idle

[A80Avant]

this i how i tune the PID as well. Also i go by the rule that i start to increase the P values until i see oscillations, and then half that number. It usually works that way.

However, it is a bit tricky as the idle needs to not only be stable on a steady state, but also become stable from an unsteady state.

for example: standing still with the car running, you can start messing with PID until the idle oscillates. If you manage to fix that using X/Y/Z values for PID, then if you start doing small accel depressions to move the rpm needle away from the idle and allow it to rest back to it's idle speed, you will see that PID may be off.... so? you alter the settings once more to compensate.

THEN, when you drive around and put it to neutral as the car decelerates, it goes off again!, OR if you increase the load by turning on all electrical equipment, it dips again and moves around.

SO you have to tune PID to compensate adequately for all those situations...

[ranz]

I have to say that with my resent settings work fine at all of these conditions... only thing why I´m going to test other settings is that you say that 160 for D is too much and I also want to educate myself

[A80Avant]

yes do that by all means, im going to try it as well as soon as i get my luggage today(rotten KLM) as all my laptop chargers are there and i have no battery to go to the car...

[ranz]

Did a lots of testing today... nothing... ended up with the same settings what I had before, with all others the idle was not so good as with them. Idle was almoust OK vith PID 0 0 0, but still with some issues.

[dkw_dude]

Post your config file. Also, you can test the IAC in the tools/IAC menu in VEMS.

[ranz]

Post your config file. Also, you can test the IAC in the tools/IAC menu in VEMS.

Conf: http://ranz.planet.ee/1.1.85.vemscfg download link: 1.1.85 conf
I tried the IAC control, I did not understand it engine stopped many times etc.

[Billman]

Conf: http://ranz.planet.ee/1.1.85.vemscfg
I tried the IAC control, I did not understand it engine stopped many times etc.

Can you give us some more details on the specs? Injectors, turbo, cams?

try these settings:

[ranz]

Can you give us some more details on the specs? Injectors, turbo, cams?

Almost original 3B, only revers IM, bigger cooler and RS2 EM, everything else is like it was from the factory.

Lambda table was like you right now suggested (just today changed it), I made it like that because originally motronic also gets richer at lower RPM-s.
Same is with ingnition (motronic has 16 degrees @ idle), but I have tried lower numbers also.
Also I have tried without idle ingnition advance and with it but with other numbers.

[Billman]

did you checked your ignition with a gun?

Also dont forget that motronic regulates ignition according to several maps with IAT and other corrections if i am correctly informed.

Please try these setting as i send you and report back.

P.S.: If you are using stock turbo then lower a lot the pressure on the top range.

[ranz]

did you checked your ignition with a gun?

Also dont forget that motronic regulates ignition according to several maps with IAT and other corrections if i am correctly informed.

Please try these setting as i send you and report. back.

Yes, ignition is checked with a gun, thatswy is the TDC after the trigger 57 not default 58.
Yes i know that I can not use always same values as motronic and get wery good results.
I´ll try them tommorrow and let you know.

[dkw_dude]

IAC lock: 0-255 equates 0-100% duty cycle, nice for testing the operation of the IAC. Try something like 100 to get ~40 %DC, add 2,5 and you have 41% etc (this is my conclusion after a bit of fiddling anyway)

My suggestions for the settings.

Idle control PID settings:
P=40, I=30, D=0
Integral increase limit: set to ~40
Integral decrease limit: set to ~10

Idle ign. advance:
Threshold for activating IAC:1

PWM idle control:
Freq 30Hz

Works good on my engine, 3B, standard cams.

[loxxrider]

My settings are

P-50
I-25
D-10

Inc. limit-35
Dec. limit-120
Deadband-20

[A80Avant]

why so high intg decrease limit? that will make the idle drop more easily when trying to correct

[dkw_dude]

why so high intg decrease limit? that will make the idle drop more easily when trying to correct

I was thinking the same. I don't want the integral part to pull down the output to the IAC too much.

[loxxrider]

yeah, I don't know...I haven't had an IAC for a while, so these might not be all of the correct settings that I tuned for before. I need to find an older map to see if its different