# Stumbling Idle



## jblackburn (Apr 14, 2012)

Valve cover hissing?


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## Clausses (Sep 8, 2014)

Did you have the A/C on? That 1.4l doesn't make enough power to run the A/C very well at low rpms. It's simply not big enough. I had the same issue. My fix was re-gapping spark plugs and I eventually got around to aiming them towards the intake. I gapped mine a bit low at 0.28", a lot of people say 0.30" is good for these cars.


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## Clausses (Sep 8, 2014)

jblackburn is right, that could be an issue, too. I had that problem and it was covered under warranty for me. If not, check GM parts direct for the valve cover. It's not hard to replace.


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## inssane (Jun 20, 2011)

*and sorry, I'm a 1.8L for reference...

When I was in the engine bay, I didn't hear any unusual hissing (as it sounds like on the video), but I will check.

I took my ride home, and it seems to 'surge' primarily under 2K rpms, whether accelerating or decelerating. Pretty consistent, but less and less as you ride around. No A/C on, I rarely run it, and I tried turning the radio, vent, all of that off - same thing.

My KN is pretty dirty, I need to clean it, could it be throttle body/MAF related?
Thanks
N


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## jblackburn (Apr 14, 2012)

Ah ok the 1.8 liter doesn't have the PCV valve issue. 

Yeah, clean your mass airflow sensor with a spray. The oil from the K&N filter may have dirtied up the sensor.


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## obermd (Mar 3, 2012)

You probably have a code reader - check for pending codes.


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## inssane (Jun 20, 2011)

I do have a code reader.
Funny thing is, the SES light has been on for months because Trifecta can't figure out why it throws a cruise control error when I have no cruise control.

I'll see what else it says.
Thanks!!


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## BowtieGuy (Jan 4, 2013)

+1 on a dirty MAF. I would start by cleaning the MAF and go from there. You may also want to disconnect the negative battery cable to reset your fuel trims in the ECU after the cleaning as well.


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## inssane (Jun 20, 2011)

OK Thanks

Is there any benefit to me tuning it to stock, cleaning MAF, disconnecting negative, then re-tuning the car, or would I just be creating work? I'll scan the SES regardless first.


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## obermd (Mar 3, 2012)

Tuning back to stock and cleaning the MAF filter would be a good test to see if the issue is related to the tune or not.


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## jblackburn (Apr 14, 2012)

Eh, clean the MAF first. See how it runs. If it still runs like crap, remove the CAI and put the stock tune back and see where that leaves you.


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## obermd (Mar 3, 2012)

jblackburn said:


> Eh, clean the MAF first. See how it runs. If it still runs like crap, remove the CAI and put the stock tune back and see where that leaves you.


Even better than my thought. However I'm still concerned about the Cruze control CEL. If stock does this then there's an underlying problem that needs to be fixed.


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## inssane (Jun 20, 2011)

Hmm, stock only threw the light once a couple months ago at the dealer (why I had tuned to stock).
Previous times going to stock has cleared the light. Dammit. Luckily there is a tuner shop across from my work, hopefully they can help me with this tomorrow, having no garage and street parking doesn't help me tonight.

Trifecta didn't know what was causing it after trying to fix it once. Any ideas as to underlying issues? I only have light stereo mods and an alarm - the lights never coincided with any of that work. 
N


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## jblackburn (Apr 14, 2012)

Trifecta's tune is usually activated (performance mode) with the cruise control switch. I wonder if they just sent you a tune for the LS that enables with the cruise control switch.


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## inssane (Jun 20, 2011)

IDK, we went back and forth a bit with logs and tweaking, I expressed I had no CC.


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## Merc6 (Jun 8, 2013)

Clausses said:


> Did you have the A/C on? That 1.4l doesn't make enough power to run the A/C very well at low rpms. It's simply not big enough. I had the same issue. My fix was re-gapping spark plugs and I eventually got around to aiming them towards the intake. I gapped mine a bit low at 0.28", a lot of people say 0.30" is good for these cars.


How did you index the plugs and tq them to spec? I tried that with the stock plugs and the T on the top and was only able to get 2 plugs to index the way i wanted them to. Didn't try that with the ones I put in earlier today.


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## Merc6 (Jun 8, 2013)

jblackburn said:


> Trifecta's tune is usually activated (performance mode) with the cruise control switch. I wonder if they just sent you a tune for the LS that enables with the cruise control switch.





inssane said:


> IDK, we went back and forth a bit with logs and tweaking, I expressed I had no CC.


So are you set up for no select a tune (Tune always on)then? try maf cleaner and q tip(or equivalent) delicately as stated above.


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## inssane (Jun 20, 2011)

The tune is set up as D being 'eco' and M being performance - so yes I can switch.

Scanned and the new one since my issue is a multiple random engine mis fire code.
Hopefully the shop can look at it today as I am locked at work. Primarily occurs during idle (P,N,D) and in higher gears when the car is 2000rpms and lower.


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## Clausses (Sep 8, 2014)

You might check your spark plug gap, too. I have the 1.4 and it really stumbles if the gap is too large. .05" was enough to make it stumble around for the 1.4. My hypothesis is that the 1.8 should have more leeway, but, my plugs were gapped very uneven (0.25"-0.40" at low and high, respectively). I have a 2012 cruze eco mt that I bought used for 14K.


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## Chevy Customer Care (Oct 29, 2011)

inssane said:


> Hi there
> Started my car this morning (CAI, Exhaust, trifecta, 40K miles) and it was idling like it had a sick cam.
> 
> Well, it bobbles between 700 and 800rpms (800ish being normal). When I get the car moving, it is fine for the most part. No stumbling on the highway, when I slow down at lower speeds though it's like the car is stumbling as the rpms lower.
> ...


Hey Nick,

If nothing helps, and you're at a loss, let me know and I can reach out to the dealership on your behalf. They may be able to pin point the problem. Feel free to send a private message along with your VIN, current mileage, contact information and a preferred dealership. 

Patsy G
Chevrolet Customer Care


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## Merc6 (Jun 8, 2013)

With it being a 2011, you may need plugs all together. How did cleaning the maf work out?


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## inssane (Jun 20, 2011)

Hi all

Thanks for your thoughts and opinions.

Late last week the shop had cleaned up around the third spark plug because there were reading a misfire on cylinder 3.
So I had my shop clean my MAF (with correct cleaner I bought) and they just did it today and they said it still stumbles a bit.

They suggested that it may need coil pack replaced, which wouldn't cost me too much at all.

I'd like to bring it to the dealer, and will PM you (thank you) - but I just don't want to be hassled with them telling me that my CAI caused something, or my exhaust, and not cover under warranty - but I guess it's worth a shot bringing it in, all they can tell me is no they won't fix it under warranty.

So this is where I sit. I will take my long ride home today and assess.
Nick


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## inssane (Jun 20, 2011)

Yep still there.

Going to set up with Chevy for a warranty inspection, and if they don't cover something, I'll have my mechanic do it (unless price is the same).

Thanks
Nick


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