Speeduino Idle Issue

[michaellatini]

Hello All,

When I cold start the engine it jumps to 15-1600 rpm and will stay there even changing, IAC settings while running. If I cold start and don't change anything, wait for a minute or even 3 minutes, shut the engine off and restart, it immediately idles at the target idle of 900 rpm. This has been tried each day for a few days now. It doesn't make sense.

All the settings in tunerstudio have been discussed previously so, it seems they are right on for now.

Can anyone shed some light on this?

Thank you for reading.

Michael

[Bruce.m]

Seen something similar yesterday working on my idle settings (open settings), but that was one off test / tune.

If you are using a stepper, there is no position sensor & the ecu has to track the cumulative adjustments. At restart the stepper re homes & then starts from a know position. I did wonder that making changes in TS while the engine is running might cause the ECU to lose track.

I modified my IACV to reduce the minimum flow it allows. so on cold start I needed to open up the valve by changing the tune in TS but as it warmed up the revs climbed further than I expected & i repeatedly changed the tune until the valve was shut. Then I keyed off and restarted (homing the stepper) and the idle was then too low & I did adjustments to open the valve.

Will need to repeat the process but I suspect you get one shot to test a warm-up tune

[michaellatini]

Bruce,

Thank you for sharing this information. I will continue to narrow the gap as suggested! Great thinking!

Michael L.

[Bruce.m]

Also. Remember your “max steps” setting in the idle setup. You can set a value in the idle chart that goes beyond that setting, but the actual valve position will not go further than the max.

[jpryorx2]

i noticed on mine that the stepper does not rehome if connected to the computer with a usb cord

[michaellatini]

Update! I was advised by Chris at speedefi to install the latest firmware for Speeduino, 2023.05. Also, it has a new setting in, Idle settings, called stepper power and set it to, always. Problem is gone. No more intermittent IAC and responds to every change at all temps. Bought a new IAC just in case and forgot to check the ohms on it so, kicked my own butt for quite a few hours yesterday.

[jpryorx2]

that is good to hear maybe it will solve my current idle issue. mine starts fine idles perfect at about 900. engine sounds like the hot for teacher intro but if i shut it down for a few minutes the idle jumps to 1500 - 2500 when start it back up thanks

[michaellatini]

that is good to hear maybe it will solve my current idle issue. mine starts fine idles perfect at about 900. engine sounds like the hot for teacher intro but if i shut it down for a few minutes the idle jumps to 1500 - 2500 when start it back up thanks

I was having the same issues. Check your settings as mentioned above and your wiring diagram and see if it's wired correct.

[Wentzel]

Hi, also have a look at your after start enrichment and mat/air temp correction when starting up again. Heatsoak of the sensor can cause it to pull fuel and affect idle and afr.

[jpryorx2]

i think its a heat soak issue the new firmware didn't change anything. i am learning as i go but literaly every time i start it i have to readjust the idle stepper other then that it runs great even with me not having a clue on tuning
jason