Car; '99 1.8, BW 6758, MS3PNP, Skunk2 TB on a EUDM flat-top (if you need any other relevant specs, let me know)

Tune; Running CL Idle, (recently) sequential injection (see attached)

(New) Symptom; During my daily 20+ min drive in to work - now that the morning temps have gotten decidedly chillier - I have noticed that the Idle Duty will "shift" up 2 or 3 points after the car has warmed up. This, in turn, will cause the idle ignition correction advance to bump up and consequently the corrected spark advance will change. The drivability impact is that after warm-up, the care will settle into a nice idle, but by the end of the morning trip, the idle goes to hell (oscillating and dying if I don't add throttle).

Hint's; I know that the car is running cold (my lovely aluminum radiator is doing TOO good of a job). I put in a 180* thermostat, but that doesn't seem to be cooperating (and I'm NOT happy about trying tp out in another 'stat - that is, my knuckles are not happy about that). But I don't know if that is the culprit, or is something else going on (like the idle control valve being heat-sensitive, or the Junk2 being...junk).

Inquiring minds want to know...

 

What kind of modifications have you made to the S2?

Your idle advance could be more aggressive. You max out at 8 and -8 correction, but not until you're -400 and 400rpm respectively from target. I usually start at -10 and 10 degrees correction by 100rpms from target, and turn it down slightly as long as it doesn't cause oscillations.

At those temps, there's also a chance you're dealing with a sticking throttle plate, those little coolant hoses on the stock throttle body are there for a reason

Your target is also a bit high at 1015, I usually don't have issues targeting 950. Are these ID 1050x's? Looks like you don't have small pulsewidth data entered if they are.

Your min DC is also high at 32.9, usually it's more like 20-25, idle duty should be able to idle 100-200 under target without issue. If you're using that high DC to keep it from stalling, other settings are probably off.

 

Thanks curly! And, to answer:

What kind of modifications have you made to the S2?Your idle advance could be more aggressive. You max out at 8 and -8 correction, but not until you're -400 and 400rpm respectively from target. I usually start at -10 and 10 degrees correction by 100rpms from target, and turn it down slightly as long as it doesn't cause oscillations.At those temps, there's also a chance you're dealing with a sticking throttle plate, those little coolant hoses on the stock throttle body are there for a reason Your target is also a bit high at 1015, I usually don't have issues targeting 950. Are these ID 1050x's? Looks like you don't have small pulsewidth data entered if they are.Your min DC is also high at 32.9, usually it's more like 20-25, idle duty should be able to idle 100-200 under target without issue. If you're using that high DC to keep it from stalling, other settings are probably offSo, to the root cause of my problem, I'm thinking of the following;

1. Get decent operating temperatures during these colder months via experimenting with radiator block-offs. Of course, the permanent solution would be to fix/replace the t-stat, but I have a re-route and getting to the housing on the back of the head is PAINFUL (literally).
2. Lower the min DC - maybe start in the high 20's and see what that looks like.
3. Do a better job with the initial values for CL idle. My IV table has values in the 40's whereas the car seems to want to idle around 35-ish. That's probably why the idle corrections go crazy during onset of CL idle.
4. Check for evidence of the throttle plate sticking in the S2.
5. Other?

 

It's not icing, just cold, aluminum heat/shrinks with temp. You'd think you'd have issues when it's hot too, but I seem to have more issues when it's cold. I'm not saying you should reinstall the baby hoses, since you can't on an S2, just that they had a purpose on the stock TB.

For small pulsewidths, go here: https://help.injectordynamics.com/he...nts/4042551859 and enter the "non linear small pulsewidth" data.

Also, once at operating temperatures, use idle valve test mode and set it to 0%, make sure your idle with the bypass is ~750-850. They're often shipped completely closed, and you're asking the idle valve to do everything.

 

Thanks, thanks and thanks

PS - I moved from a MS2PNP, to the MS3 and every day is a "learning day".