i've had my MSPnP (MS1) in for a good few years now, all of a sudden in the last few months, the closed loop idle is acting crazy. sometimes when i start the car, it idles around 1000 and settles to 900rpm quickly (like before it should as it's still cold) and sometimes it starts normally but the idle rises to 2000rpm - for about 10 minutes then it goes normal.

Idle DC is set to start on 26, idle on 19, minimum 18 (TPS threshold is 2). but now it's starting, and fixed on 18 (TPS is zero). I raised the minimum to 19, and when i burnt that in, the idle DC then started to drop down and down to zero!

i can rescue it by burning open loop idle and then going back to closed loop, but it only lasts like a week before it starts going messed up again.

any ideas? should i just reburn the tune or the firmware?

 

Your idle valve might be going bad. Unplug it and see if some of the symptoms go away, mostly the hunting idle. If so, just replace it.

 

i thought that but as soon as i switch to warm-up only, everything is fine and the idle speed responds to any changes that i then make in the settings. and when i change back to closed loop, again it's fine and responds to closed loop. then after a few days or weeks, the MS will get stuck in its rut again and doesn't respond sensibly to any changes.