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P0171 - System Too Lean - Bank 1

1064 Views 8 Replies 5 Participants Last post by  davidtranlds
Hi everyone,

Name's David from the land down under.

I've recently purchased a used Holden Cruze 2012 SRi-V JH Series II, 1.4L turbo petrol.

I had a check engine light come on, but after some driving, it went away.

Day or two later, it came on again and now it's permanently on whilst I drive.
I had also refueled with Unleaded 95 (manual says to use 91 but 95 also worked for a little extra performance), not sure if the light returned after or before I used the 95, but recently received my OBDII reader and that's how I got the code above.

I noticed the STFT would be around the -3% to +4% when idling, but LTFT would be around +30%.
When accelerating and driving/cruising, they'll both float around the -5% to +5%, sometimes going up to +10% depending on when I'm accelerating or decelerating heavily, or something, too random for my basic knowledge to pinpoint.

I do notice when I come almost to a stop, STFT jumps to around +15% then drops back down again once I've stopped, or start accelerating again.

I did some basic troubleshooting, tried the water spray method but I think it was too windy or something.
Anyways, tried the purge valve and when the car's on idling, there's suction, so I believe that's one problem.

But based on the above STFT and LTFT details, could there be anything else?

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That's always the case ain't it?
Can never detect the issue when you want to for troubleshooting xD

I'll look into the PCV as well.

The dealership I bought it from said they'll organise someone to take a look so we can get it sorted this week, free under the 3 month warranty.

We'll see what happens
Been watching a few more videos and reckon I need to check my MAF sensor also.

Is there a list somewhere of what all my ODB2 readings should be sitting on?

Like in the video I watch, for a Toyota car, the guy mentioned having his MAF(g/s) in the 2-3 range, preferably higher 2s to 3 range.

What should the Holden Cruze be?

Similarly, O2 sensor around 3.3, for the 14:1 fuel ratio.
How about the Holden?

So stuff like that, a table that lists what all the standard values should be to know what's in range and what isn't?

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Thanks for the tip 72chevman
Will have a look today, should have some time.

Also, got the other valve replaced at the dealership where I bought the car, typical small dealers, they replaced with a second hand part.
Nevertheless, LTFT idles around an average of 11% now.

An improvement at least will continue checking for more possible leaks and whether the replacement itself might need a replacement of its own lol
I'll give it another check - everything seemed tight first quick check I did.

Something I noticed, for LT averages 11% on idle.
After some driving, it might eventually average 4% or so.
But may sometimes go back up to 11%, or even more, after some time, then back down again.
So on consistency yet, but generally on the 11% and lower side.

So hard to say if the replacement valve is on its way out also, or if there's another leak.
Will have to ask the mechanic to do a smoke check when I bring it in for service.
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