Valentinik

I've got my car to idle on the MS at a steady 950-960rpm but im struggling in getting it to idle with the valve plugged in.

Without the valve plugged in it will hold a steady idle a 950-960rpm. When i plug the valve back in though the idle will fluctuate between 900 and 1100rpm every 2-3 seconds after coming to a stop or touching the throttle.

The valve settings im using are below as recommended by reverant:



Also attached a short datalog i did. It starts with the valve plugged in and then you can see the idle becomes steady when i unplug the valve.

Any suggestions on what might be causing the unstable idle?

richyvrlimited

iTrader: (1)

I'm on my iPhone so can't see the log, but are AFRs steady? If not that'll cause idle instability, as will if it's too lean.

if the above are good, try reducing I and P until idle is steady.

Valentinik

They seem to be quite steady with it unplugged but as soon as i plug the valve in they fluctuate with the idle.

richyvrlimited

iTrader: (1)

Yeah so you need the AFRs to be steady as the rpms are higher/lower it's a very tricky balance I still haven't nailled it.

Set it to open loop and tune the AFRs to be consistent in-between the idle target areas I.e. 900 rpm -1200rpm

Braineack

iTrader: (62)

Too much I.

you need to retune your PID gains settings. try P-10 I-42 D-5.


and your operating the valve at an odd frequency. use 6 for the multiplier.

Valentinik

i tried pwm warmup and the afrs were still just as stable as with the valve unplugged, only in closed loop they were fluctuating

I switched back to closed loop and tried brain's settings and it seems to sit around 930-950 which is a lot better. I'l give it a try during the week from a bone cold start but its a huge improvement.

Thanks Braineack

richyvrlimited

iTrader: (1)

There's a guide on Nutz for tuning PID as is there one in the MS manual

Both would be worth a good read