No high idle on a cold start

[5ktq]

Had an interesting morning, woke up, power was out - first snow of the year, hovering right around freezing, so not super cold.

Went out and started the car. Started up fine but there was no high idle, it just idled at normal (warm) temperature. Seemed like it had enrichment because it did start and didnt stumble when I pressed on the gas.

SAI didn't seem to run either, but I may have missed it (had defrost on, kinda loud).

Sooo... Does anyone know what temperature sensor is used for what? I can't really see it using one input for enrichment, and the other for (is car cold? = high idle, run SAI).

I guess maybe it's not cold enough that enrichment matters much, hmmm

Gauge on the cluster seemed to work properly.


Also - there's always that one moron that doesn't know how to treat traffic lights when the power is out.

[seanf86]

when its below a certain temperature the B6 doesn't run the SAI, don't ask me what temp it is, I would wager its around the freezing mark. Any B5 I've ever owned with SAI however seems to run it all year round.

[5ktq]

Same thing happened this morning. wtf.

So

6AM yesterday - no high idle
11am lunch break - works fine, high idle for a little (car and weather would be warmer here)
4pm when i go home, works fine

7am today, same thing, no fast idle.
starts right away, idles at 400 for a sec and then goes to normal 780. Doesn't stumble when you press on it.

Logged in on VCDS (after it had been idling a minute or two, took a bit for the computer to boot)
Water sensor: 20C, sounds about right
air sensor: 0C, also about right

Is there some other channels I should be looking for?

[seanf86]

Same thing happened this morning. wtf.

So

6AM yesterday - no high idle
11am lunch break - works fine, high idle for a little (car and weather would be warmer here)
4pm when i go home, works fine

7am today, same thing, no fast idle.
starts right away, idles at 400 for a sec and then goes to normal 780. Doesn't stumble when you press on it.

Logged in on VCDS (after it had been idling a minute or two, took a bit for the computer to boot)
Water sensor: 20C, sounds about right
air sensor: 0C, also about right

Is there some other channels I should be looking for?

you shouldn't be looking for anything, sounds like its running just fine, the green coolant temp sensor tells the ecu what to do about a cold start and at a certain temperature the ecu will run the sai pump and high idle. I bet if you start the car for 30 seconds, shut it off and restart it you will get a high idle with the sai running

[5ktq]

Yep, looks like this is normal behaviour, some emissions thing. super weird. Never seen another car do this (incl several 1.8T VWs). neat.

[Mr.Avant]

I live in a very cold climate during the winter (-30*C is not uncommon) and notice this same behaviour. Most very cold days it will high idle, but not every single time.

Sent from my SM-G920W8 using Tapatalk

[5ktq]

I'm in Sask, so we've got similar weather, and why I was a bit concerned.

Guess we'll see what it does when it gets colder!

[seanf86]

Manitoba here, was +26C Monday, I think we hit 7 or 8C today...

[5ktq]

Just below freezing again this morning. Idled like shit (only hitting on 3/4, maybe) for the first few seconds then to normal 780rpm. I'm not the biggest fan of this design choice.

I hope it ditches this emissions jazz and goes into some sort of severe-conditions-ignore-emissions high idle when it's actually cold cold.

[old guy]

The cold start strategy is not causing your problem. You have some other issues going on.