Re:2012 Chevy Cruze (1.4L Turbo)

A 2012 Chevy Cruze came into the shop yesterday with a rough idle and CEL on. I scanned codes and got the following:

P0442 - EVAP system small leak
P0106 - MAP performance 
P0131 - HO2S1 low voltage
P0496 - EVAP flow during non-purge 
P1101 - Intake air flow performance

Voltage on 02 sensor 1 only fluctuated from .005V to .020V and the vehicle would not go into closed loop. I replaced that 02 and was able to get it into closed loop, but I could really use some help with direction at this point. STFT is at 35.2% and LTFT is at 34.4% constantly. O2S B1S1 is now reading .020 - .025V and O2S B1S2 is reading .150 - .155V with the snap thottle test. 

I did a smoke test through a port on the intake and found no leaks. I did not have access to a bi-directional scan tool to see if the purge solenoid responded to commands, but I will have access to one on Tuesday when I get back into work. At this point I'm feeling like I made the wrong call on changing the B1S1 O2, so any help with direction would be greatly appreciated.

Thanks in advance for all of your help!

 

Is it lean at higher rpms or only at idle?if at idle only check the valve cover diaphragm you'll probably hear it hissing with engine idling if you put your finger over vent and feel vacuum or hear the hissing go away the its ruptured and the valve cover will need replaced but 99% this is caused by a failed check valve in the intake manifold and will likely need replaced at the same time, the codes suggest the purge valve is bad as well, I use a boost leak tester and pressurize the charge air cooler and check all of these for leaks sometimes the valve in the pcv pipe is bad as well (it connects at turbo inlet it should only flow air 1 direction as well)

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I agree with everything Ben said. The intake non-return valve, the valve cover AND the purge valve are all suspect in this engine.

The purge valve can be pretty quickly ID'd by running the Purge/Seal on the scan tool. With the vent sealed and the purge at 0%, the fuel tank pressure should be atmospheric. If you see a vacuum building, the purge is stuck open.

Fuel trims get much better with increased throttle and it runs much smoother. That diaphragm is definitely leaking on the valve cover. I'll check on the purge valve tomorrow when I have access to a better scan tool. Thank you both for the help!

I see that Dorman makes an "OE Fix" version of this intake manifold. Do either of you have experience with this? I'm wondering if I should recommend that or the OE to the customer..

 

Tyler and others may have a different experience but I've used both through the years and have not had any trouble with the Dorman on these engines, don't just replace the valve cover without fixing the problem of boost pressure in the crankcase (almost always the intake manifold) (I agree with pretty much everyone else that Dorman isn't known for "quality") I just have not had any issues with these pieces

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I've used the Dorman intake several times in the past. None came back, amazingly. 

Check carefully for the orange 'nub' of the non-return valve in the intake. If you can't see it, it's intake time.

While you have the valve cover off, take a moment to check the upper timing guide bolts. Retorque as needed.

www.scannerdanner.com/forum/diagnostic-t...ck-sensor-codes.html

The orange nub of the non-return valve was missing and the purge valve was stuck open. We ended up going with the Dorman intake, OE valve cover, PCV pipe and purge valve and the car is fixed!

Again, thank you so much for the info. It was very helpful!

 

Ben,
I'm very interested to know how you knew to zero in on the valve cover diaphragm. I went the direction of the 02 first as Archer did. Clearly, your way was correct in finding the problem.
My thought was with the 02 voltage stuck lean, I would test it first to correct the high trims then go to the MAP codes then the EVAP.

wrote:

Ben,
I'm very interested to know how you knew to zero in on the valve cover diaphragm. I went the direction of the 02 first as Archer did. Clearly, your way was correct in finding the problem.
 

Known pattern failure,,,statistical diagnostics.

Yeah, those LUV/LUJ engines have had failing intakes and valve covers for years. :lol: For me, the P1101 is the really valuable code. The set criteria pretty well spells out a vacuum leak.

PIP5197M helps: