# Idle relearn?



## Fightingmarmot (Dec 29, 2016)

Well that sucks, I tried putting the transmission in neutral and even manual mode. Still pulsing at idle. I'm so confused


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## Fightingmarmot (Dec 29, 2016)

Oh this is embarrassing. I guess it's the o2 sensor. Gonna replace both of those. Sorry about that everyone...thanks. 

I still have no idea what an idle relearn is, never had to deal with it before. Not on the service manual that I can see.


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## ChevyGuy (Dec 13, 2014)

I know idle re-learn was something you worried about on older computer cars. I'm not sure as it applies to the Cruze.


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## jblackburn (Apr 14, 2012)

Yeah, it sounds like either a MAF or O2 sensor issue (or a leak somewhere in between). Are there any pending or stored codes for the O2 sensor?

Most cars re-learn the idle within a drive cycle after disconnecting the battery. When I put a new battery in the Toyota, it quit dipping the idle after the first two stops.


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## Fightingmarmot (Dec 29, 2016)

I'll check pending codes when I get the chance, gonna have to get my dad's scan tool. I really thought it was the valve cover but I came across an article here about an o2 sensor replacement for a similar issue and it doesn't hurt to replace then but I guess it helped a lot lol. I didn't notice any stumbling or hesitation. It did kind of jerk uphill sometimes kind of hard to describe what was happening there. I'll see if that's gone too. Ugh I grew up fixing cars and I don't understand this one at all. 

Thanks for the help! I don't see mention anywhere of an idle relearn so I'm not gonna worry about it. Car seems happier and doesn't make that loud click to boot.


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## jblackburn (Apr 14, 2012)

If you want to save yourself a little bit of $, you can generally just replace the front sensor. The post cat sensor more or less just monitors the catalyst output and depending on the ECU, has little to no impact on actual engine control. 

I don't even know off the top of my head how much a Cruze O2 sensor is, but seems like parts are *much* cheaper for this car than my European one.

So you've already gone through the replacement and that took care of it huh? That's good to know for other members - I can think of at least two that had this weird idle hunt happen after a valve cover. I'll see if I can dig up their threads. Wonder if the oil being sucked through everything helped foul that sensor.


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## Fightingmarmot (Dec 29, 2016)

Yeah just the front one. Cost $52 at a local autozone. I had it off before to check the turbo I should have replaced it then, didn't occur to me.


I had a 97 Lumina at around 170k it threw I think 6 codes at me and it ended up being the o2 sensors. I am not sure why it didn't throw a code, I'll monitor it I guess.


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## Fightingmarmot (Dec 29, 2016)

What's weird is I can recreate the issue when I'm standing still, if the windows are all the way rolled up and I pull the driver's door switch buttons up for the two rear windows the car shudders and rpm drops for a second, which makes sense I guess because it's drawing power. That's what's getting me here it was doing the same thing at idle. I'm skeptical but I'll see what happens.


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## jblackburn (Apr 14, 2012)

Fightingmarmot said:


> What's weird is I can recreate the issue when I'm standing still, if the windows are all the way rolled up and I pull the driver's door switch buttons up for the two rear windows the car shudders and rpm drops for a second, which makes sense I guess because it's drawing power. That's what's getting me here it was doing the same thing at idle. I'm skeptical but I'll see what happens.


Huge load on the alternator since the window regulator isn't going anywhere. I think I recall that mine dipped a bit too when under a sudden electrical load.


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## Fightingmarmot (Dec 29, 2016)

Hmmm okay it's still doing it. The car is happier but it started doing it again. One thing I didn't check was the cooling fan, I wonder if it's cycling. I really think it's a power draw somewhere. I remember someone telling me that it has 2 coolant temperature sensors and one went bad on theirs causing the fan to constantly start/stop. It's not the compressor, rechecked it.


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## EricSmit (Dec 21, 2016)

Worth noting, below 32 degrees your AC won't work.


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## Fightingmarmot (Dec 29, 2016)

The compressor runs when it's on defog which is what I used to test it.

My car doesn't pulse/jerk uphill anymore so that's weird. Whatever I'll just wait for an engine light, I don't want to keep guessing I have no idea how modern cars work lol.


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## Fightingmarmot (Dec 29, 2016)

Update: Took the throttle body off and cleaned it, it was pretty bad. Put in a new MAP sensor as well. Seems to have helped but I'm still testing it out. (MAF cleaned as well).

Another dealer had no idea what they were talking about concerning an idle relearn. Car idled high for a bit, wandered around then settled after reinstalling the throttle body.

It still drops a little when coming to a complete stop but then it's totally fine. My jerking uphill is completely gone and hasn't come back.


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## Fightingmarmot (Dec 29, 2016)

Hello!

For the most part the idle issue is gone. I put another o2 in lol the one before the cat. When I come to a complete stop it does a small bounce and then it's fine.


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## EricSmit (Dec 21, 2016)

Excellent news!


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## scuba113 (Mar 1, 2017)

I had the same issue. Took it to the dealership and they could not find anything wrong. Still happens every once in a while don't know how to correct the problem.


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