# 2012 Cruze ls 1.8 rough idle



## Lilgofdecatur (Feb 28, 2021)

I have a 2012 Chevy Cruze ls with a rough idle I have changed literally everything on this engine what else could it be at idle long term trim is 14.7-15.6+ any suggestions valve cover done purge valve changed new head new phaser new vvt solenoid new cam sensor ???? Sometimes engine will take a few extra seconds to start when restarting hot???


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## JLL (Sep 12, 2017)

Positive fuel trims indicate that the ECM is having to add fuel to obtain the commanded air-fuel ratio.

It could be things like:

A small vacuum leak
A dirty sensor
A partially plugged fuel injector 
A weak or failing fuel pump

Ect ect ect


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## Lilgofdecatur (Feb 28, 2021)

On my live data I see a constant 58psi so fuel pressure seems ok? I’ve cleaned the maf sensor it’s a very strange design? I just changed my ignition coil again today was getting a misfire but no codes and sometimes random misfire code. Changing the coil seems to have smoothed up things a lil but not 100 percent. It feels like a lurching pulsating feeling in drive at times. Also changed valve cover the whole cover? Confused?


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## JLL (Sep 12, 2017)

Has the been engine well maintained? Spark Plugs, Throttle Body cleaning, Fuel System cleaning ect


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## Lilgofdecatur (Feb 28, 2021)

Yes spark plugs changed ngk iridium cleaned throttle body all of the above. Just having a rough idle which is also affecting my transmission shift points.


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## Crewz (Jul 12, 2011)

I'd take a look at the fuel injectors. Surging at idle could also be a vacuum leak. Did you get a genuine GM cam cover? Check all the hoses. A lot of the plastic hoses are known to crack. Go around and check them all. I hope you get it figured out.


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## Lilgofdecatur (Feb 28, 2021)

I had a genuine replacement at first and then I went aftermarket same result no difference tbh. I have done the timing and phasers I did get a code this morning will update when I replace it . I changed the intake but not exhaust.







Ok


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## Lilgofdecatur (Feb 28, 2021)




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## Crashtrex (Dec 11, 2020)

Trim loooks good .. if wasn’t your injectors what about the “plastic intake manifold”
or voltage drop somewhere..
Gas pedal is electronic not cable so perhaps a slight delay there .?


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## Lilgofdecatur (Feb 28, 2021)

It’s like when I’m idling I have a lot of vibration it’s like the engine is pulsating. To me it seems like a misfire but no codes maybe 🤔 jus maybe it could be my plugs I’m running ngk 6418 instead of. Ac delco 41-122 any thoughts???


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## JLL (Sep 12, 2017)

Lilgofdecatur said:


> It’s like when I’m idling I have a lot of vibration it’s like the engine is pulsating. To me it seems like a misfire but no codes maybe 🤔 jus maybe it could be my plugs I’m running ngk 6418 instead of. Ac delco 41-122 any thoughts???


Engine mount(s)?

Enough misfires to make the engine pulsate *WILL *throw a code.


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## Lilgofdecatur (Feb 28, 2021)

I’ve changed the mount on the passenger side. Let’s say pulling up to a red light a slow roll it feel like I’m driving a cammed v8 ? The car jerks foward something is off


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## JLL (Sep 12, 2017)

Lilgofdecatur said:


> I’ve changed the mount on the passenger side. Let’s say pulling up to a red light a slow roll it feel like I’m driving a cammed v8 ? The car jerks foward something is off


Automatic or manual transmission?


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## Lilgofdecatur (Feb 28, 2021)

Automatic


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## Lilgofdecatur (Feb 28, 2021)

What would cause a rough ride I jus changed the shocks could it be control arm or tires ??? Steering also shakes and pull to the left ???


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## JLL (Sep 12, 2017)

A rough idle is not caused by any of those things. The reason I asked out the transmission is that the automatic transmissions actually shift into neutral at a stop and the shift back into park when you start to release the brake.

Did you ever do a compression test?
I think I remember maybe talking to you about that.


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## Lilgofdecatur (Feb 28, 2021)

Update still haven’t gotten around to doing a compression test but I just changed over my NGK6418 spark plugs toAC Delco 41-122 and my idle is still rough 🤦‍♂️ This is very confusing could it be my ignition coil I have changed it twice already same result??)?(?) It feels like a misfire I have tried a smoke test but I didn’t find any leaks


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## Lilgofdecatur (Feb 28, 2021)

Lilgofdecatur said:


> Update still haven’t gotten around to doing a compression test but I just changed over my NGK6418 spark plugs toAC Delco 41-122 and my idle is still rough 🤦‍♂️ This is very confusing could it be my ignition coil I have changed it twice already same result??)?(?) It feels like a misfire I have tried a smoke test but I didn’t find any leaks


Also I just changed my brake booster vacuum switch made a big difference in safety 👍


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## Lilgofdecatur (Feb 28, 2021)

Still in need of help with this problem. Car has been idling rougher I really don’t understand what’s going on the other day I got a p0171 and p0300 and p0455 Already changed the purge valve and gas cap but I do get a message occasionally saying tighten gas cap ??? Shifts are rough 🤷🏽‍♂️ I don’t understand why 1.8 idles so rough


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## Lilgofdecatur (Feb 28, 2021)

So a new issue my fuel trims are high around 20% at idle but when I unplugged my maf sensor my levels went to around 3% 🤔 which is normal. When I plugged it back in my levels went to around 7%. Could my MAF be the problem ???? I tried cleaning it before but no success.















Also randomly got these two codes when my fuel trims were high around 20%


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## Lilgofdecatur (Feb 28, 2021)

Hello still need help with my issues here’s an update car still runs rough also shifts roughly as well. I occasionally have been getting a p0455 code and I already changed gas cap and purge valve ? My main issue is the bucking at idle. I have high long term fuel trims at idle and when I unplugged maf sensor my fuel trims went back to normal any ideas ???


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## CruzeMatt (Dec 29, 2021)

Ive got a 2011 Cruze 1.8L and I have the exact same issues its crazy! Cannot figure it out for the life of me. New plugs, new coils, cleaned MAF. Did you ever figure it out? Lemme know please.


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## donnier6972 (Dec 8, 2021)

Your rough idle sounds to me like your air fuel mixture equipment has an issue somewhere. Could be your mass air flow sensor, knock sensor, throttle position sensor, purge valve, on and on ad nauseum. I had the same thing happen to me iny '13 1.8. When I would come to a stop, the car seem to want to surge, release, surge, release over and over. I put a quart of transmission fluid in it and it stopped surging. I still have my at idle on startup problem to replace the purge valve sensor today. Already replaced the knock sensor, and this is a pretty cheap second step for me, hoping I don't have to replace the mass air flow sensor as those bad boys are pretty expensive. Hope this helped some, and good luck.


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## donnier6972 (Dec 8, 2021)

CruzeMatt said:


> Ive got a 2011 Cruze 1.8L and I have the exact same issues its crazy! Cannot figure it out for the life of me. New plugs, new coils, cleaned MAF. Did you ever figure it out? Lemme know please.


Check the transmission fluid. Please let me know what you find.


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## donnier6972 (Dec 8, 2021)

donnier6972 said:


> Check the transmission fluid. Please let me know what you find.


And I will let you know how I fare changing my canister purge valve sensor. I already did the knock sensor with no joy.


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## CruzeMatt (Dec 29, 2021)

donnier6972 said:


> And I will let you know how I fare changing my canister purge valve sensor. I already did the knock sensor with no joy.


Sorry didnt see your replies. I put all new trans fluid same issues. Also i had found a leak from the heater pipe going out of the throttle body and into the coolant reservoir. Leak is fixed. Could my throttle be damaged? Could never find the leak and driven with it for almost 2 years probably.


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## CHEVYCRUZE RS (Mar 29, 2011)

Check your spark plugs and your negative cable on your battery, some first gens have a problem to ground causing a failure on start sometime, My car has this issue as well ONLY problem in 11 years of owning her and done tons of mods to her!


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## CruzeMatt (Dec 29, 2021)

CHEVYCRUZE RS said:


> Check your spark plugs and your negative cable on your battery, some first gens have a problem to ground causing a failure on start sometime, My car has this issue as well ONLY problem in 11 years of owning her and done tons of mods to her!


Okay, how should I diagnose this ground cable.
Please read my post about everything ive been doing. 2011Chevy Cruze 1.8L Throttle issue


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