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Discussion Starter · #1 ·
Hi all! I'm a newbie to the forum, but I am looking for some that have more experience than I do with this vehicle! I have a 2017 Trax AWD 1.4L with about 81,000km (~50,000miles). I am the second owner so I suspect warranties are void?

Starting about two weeks ago I got the dreaded MIL. Over two week period, after clearing some of them, all of the following codes have appeared at least once:
P0171-System too lean (bank 1) - has appeared multiple times
P015B - 02 sensor delayed response, lean to rich (bank 1 sensor 1). This is probably the most common one, has appeared multiple times
P0299- Turbo underboost condition (only appeared once)
P1101 - Mass Air Flow sensor out of self test range (only appeared once)
P0496 - EVAP emission system high purge flow (only appeared once)
P2270 - Oxygen sensor signal stuck lean bank 1 sensor 2. (only appeared once)

So far I've:
Checked PCV valve/diagram. it's in good condition.
Removed EVAP solenoid valve and tried to blow through it. I could not so it's not stuck open.
Cleaned MAF sensor, replaced the air filter and check clamps.
Put hands-on with every hose I could to test for tight connections.
Looked for vacuum leaks with a water bottle test, but none that I could see.
Checked the data stream for O2 sensor. The sensor responds well to the accelerator spike test. There are times when the voltage is lower than I'd expect (0.03 V). Also, there are times now and then when the voltage reading holds constant for 3-4 seconds either in the .7V range or 0.3V range.

I know the list of possible issues for a P0171 is huge, but I tend to think it may be more air-related? I just think that there is too fuel miles on it to have any significant fuel delivery issues.

I suspect it might be the O2 sensor, but I don't want to throw parts at my car... I'm hoping that I'd be able to have a clear diagnosis before buying parts.

Does anything I've said here ring any alarm bells for any of you?
 

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For most of these codes a leak is most likely. Did you check the orange nib in the intake?

Did you pressurize the boost side of the the intake to see if it held pressure?

Do you have means of check how much vacuum & boost your putting out?
 

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Discussion Starter · #3 ·
Thank you Traxy. I have done none of the items you've listed, but will at the first opportunity.
A few questions:
1)The first picture isn't the clearest, where should I be looking for the orange nib? Is it right to assume that if its not there then I likely have a leak?
2) What would be the procedure in attaching a pressure gauge and pressurizing the boost side of the intake?
3)I don't have a means of checking boost and vacuum, but I'm sure I could figure something out (I don't mind purchasing tools, just not unnecessary parts ;)). What would be the recommended places to attach a gauge, and what should I be looking for?
 

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1)The first picture isn't the clearest, where should I be looking for the orange nib? Is it right to assume that if its not there then I likely have a leak?
I took that picture with my endoscope from inside the intake. You just pop the hose from the top of the intake and look down in with a flashlight. If it isn't there you will have boost and vacuum problems, sometimes it takes out the PCV regulator on top of the valve cover if not looked at.
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2) What would be the procedure in attaching a pressure gauge and pressurizing the boost side of the intake?
You remove the intake to the turbo inlet, I made this gizmo adapter from parts from Princess Auto. Installed as you saw in the second picture. Pressurize to 20 PSI and it should still be greater than 15 PSI after 1 minute. Mine was at 9 PSI before I undid the hoses, cleaned, re-installed and tighten the clamps. 17 PSI after.

3)I don't have a means of checking boost and vacuum, but I'm sure I could figure something out (I don't mind purchasing tools, just not unnecessary parts ;)). What would be the recommended places to attach a gauge, and what should I be looking for?
$5 for a bluetooth OBDII adapter and a free Torque APP. Some work better than others.I have a few different ones this one works okay.

 

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Discussion Starter · #6 ·
Those videos were great! I haven't built a boost pressure tester yet, but I did look in the intake. There's definitely no orange nib there...There was quite a bit of oil deposit build up though. Is this normal?

Does that mean I need to buy a new intake?
Is it still worthwhile to build a boost pressure tester and do the pressure test?
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Discussion Starter · #7 ·
Update: After watching the video again, I decided to clean it with a qtip and alcohol, and voila, PCV check valve appeared.
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I guess I'll check boost and vacuum pressure next...
 

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Discussion Starter · #8 ·
Update- I put the jig together and tested the pressure... it showed about 9-12 psi drop from 20 psi in 1 minute. I found a leak in the connection from the PCV hose to the intake manifold. I spent the rest of the day looking for others but couldn't find any. Turns out my PCV hose is missing an o-ring and plastic washer.

I don't know if warranty work was done before I bought the vehicle and the o-ring was lost then. If this was the case, I would expect the MIL to come on a lot earlier than now- I've had it for nearly 2.5 yrs. The only other time I could have lost it was when I was looking for the PCV check valve. If that's the case then it means I haven't found the source of my problem.

Does anyone know the sizes of the o-ring and gasket? otherwise, I'll have to buy a new hose.
 
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