JB4 Cold start questions

[jinthadell]

I remember before I installed the JB4 and cold started the car, it would idle high and pretty loud, for a cpl min. Now when cold starting it will idle high and loud for maybe 30 sec about 50 % of the time. The other 50% it’s idles down immediately and super quiet. Is that a setting in the JB4?

 

[Thomby]

I don't think the JB4 does anything to idle, but the engine temp will change how long you stay in high idle.

Now that it's summer, I pretty much only get the "cold start" blip and high idle if I haven't run the car since the prior day...it'll stay warm enough to do a warm start (quieter and settles to low idle right away) for hours. A morning drive will mean my car warm starts even late that afternoon. Could that be what you're seeing?

 

[jinthadell]

I’m just used to it being pretty loud in the mornings and now it’s just loud occasionally. Yeah and I didn’t think about it being relative to actual temperature. Im sure it being 80* when I leave in the morning doesn’t warrant a high idle to warm up to operating temperatures. It’s usually a simple answer but my ADD always makes it out to be way more complicated. Lol. Thanks for the insight.

 

[Thomby]

I’m just used to it being pretty loud in the mornings and now it’s just loud occasionally. Yeah and I didn’t think about it being relative to actual temperature. Im sure it being 80* when I leave in the morning doesn’t warrant a high idle to warm up to operating temperatures. It’s usually a simple answer but my ADD always makes it out to be way more complicated. Lol. Thanks for the insight.

I notice it because I usually remote start it from inside the house, and the cold start rev is much more noticeable through the wall, vs. the warm start that I barely hear.

And if it's been 70-80 all night, your block and coolant are probably at that temp, but if you drive somewhere in the morning, they'll be cooling off from the 150-180 range in your 80-90 degree garage with no airflow. Given how much thermal mass there is, it wouldn't be surprising to still be at 120-130 hours later when you start it again.

 

[oddball]

The startup cycle is entirely dependent on a wide variety of factors - ambient temp, engine temp, oil temp, battery voltage, battery temp, A/C settings, etc. It'll react as quickly as it thinks it can to settle down to the normal idle.
There's a pretty good chance that there are big steps in the idle tables: e.g. ambient 80deg has a 10 second cycle while ambient 79deg has a 30 sec cycle. Just depends on how much time they spent messing with those areas at Kia, and that's a minor convenience issue, so they're not going to spend THAT much time (as long as they meet emissions requirements).

Anyway, it could be one of dozens of things that you might not notice that decides how it wants to do the start cycle.

JB4 has nothing to do with it. Remember that, literally, the only thing the JB4 can do (ignoring o2 wires and EWG wires) is fake out the MAP and TMAP readings, which it only does when MAP >0 (engine is under boost) which sure as shit doesn't happen at idle.