JordanOfGilead

I've noticed this a couple times now.
I've got a 2016 tC2.5 with just under 3000 miles on it. Driving down the road on the way to work or the store or whatever there is a traffic light that I hit right when my low engine temp light turns off pretty much any time it's more than 40 degrees outside.

Sitting at that light, in neutral, foot off the clutch, the idle sits around 750-800 rpm, but the car will shudder like it's on the edge of stalling.

Only does it right after the undertemp light turns off, so my guess is that the engine isn't actually at a high enough temperature for the idle to be that low yet.

Has anybody else had this problem? If so, how did you resolve it?

JordanOfGilead

Nothing?

FreedomPenguin

Nope. Havn't had the issue. Tomorrow morning if its cold, i'll make a note to watch my tach. Maybe record it, see what it does. but generally it runs fine, just its cold. Never had a shudder / dieing feeling EVER. My idle stays around 1100, never lower if i recall.

On cold ___ days, lilke negatives I use my heated seats and remote start on days where I am just cold. D: alaskan life taught me, no reason to stay cold.

JordanOfGilead

That's odd. When my engine gets to fully warm temp my idle goes as low as 600rpm. How is the cold idle controlled in these engines? Is it an old-school style idle air control valve, or is it something electronic?

FreedomPenguin

All engines are electronincally controlled now a days.
Im not sure why yours drops to 600, mine has never been below 900-1000 ever in my entire time owning it.
3 years (75kmiles)

your car is different year though, mine is the 13 yours is newer. small things could had been changed.

Manualsonly

Jordan, I have a '14, manual transmission as well. I've notice this happens occasionally with me as well. It will drop its idle down to about 600rpm then rise back up. If you tap the gas it will bring it back to normal, around 1000rpm. I've let it run its course too see if it will get low enough to stall, but the lowest I've seen it go is 600rpm. I have a catback exhaust and sometimes I wonder if it has something to do with back pressure. Do you have a factory exhaust and intake?

JordanOfGilead

I have the stock exhaust and intake from the factory, but they installed the floor light kit at the dealership about a week after I bought the car and I had a really bad issue with roaming idle for about a day after that happened. It got better (it was spiking around 2500 and dropping to about 600) but my idle still doesn't really sit still, but it also doesn't go above 1000 after I've driven around for a few minutes. I think the vibration I'm getting around 700-800 is just the engine hitting the right frequency to vibrate the car. It still makes me a little uneasy though.

talt2008

Completely normal... unfortunately. Trust me you have nothing to worry about. My car has always had a strange idle. I can only think its because of the drive by wire. BTW I bought my 2011 new and have 193,000 miles on it. Also its stick.

tC_toph

I have noticed something similar with my 2016 automatic tc, Usually only happens when I am using something (wipers, headlights, stereo etc) the idle will sort of slowly fluctuate between 600-1000 rpm. when it drops down i feel a super slight shake (doesn't feel like its gunna die but you can feel the shake). i don't even have 500 miles on mine so I feel like its normal?

stock intake and exhaust