System too lean off idle bank 1 (no power)

[boxme2]

Hi All,

Got a 2007 Vrs Octavia,
Has done about 180,000ks, in the 3 owner as far as I can tell so service history is hazy at best.

Recently noticed a significant lack of power and a couple fault codes:
System too lean off idle, Bank 1
and
Idle control system RPM higher than expected.

I have recently replaced plugs and packs, it has a basic air intake other than that she is fairly stock.
Any clues as to where to start with this?
From what I have read possible causes include:
Faulty air/fuel ratio sensor/oxygen sensor (AFR/O2)
or
Faulty mass airflow sensor (MAF)

Do I just replace both and hope for the best or is there a way to test either of these 2 components.

Cheers, and may the boost be with you... (cause at the moment it aint with me)

[jnrdavo]

I'm assuming that you're using vagcom/vcds? Is that the only error?

Lack of power on take off, on full throttle?

I would look at unplugging the MAF and seeing what that does? Does it seem more 'consistent' power?

The other place to look would be a boost leak, so check out the pipe work for small cracks and the PCV.

[boxme2]

Thanks for the response,

Power is just flat across the whole pull, almost like boost has been turned right down, still runs smooth, does idle high on occasions.

it did a similar thing last week but came good, this time it seems more permanent.
I am using OBDEleven to scan and just the 2 errors, System lean on bank 1 and high RPM

*Edit*
3 Errors
P2177 System too lean off idle, Bank 1
P0507 Idle Control System RPM Higher than Expected
P1602 Power supply terminal 30 Voltage too low - (this one popped up after I pulled the battery out for a few min)

Cheers,

[boxme2]

OK,

Disconnected the MAF and went for a drive, getting a bucket load more power now, much more constant and more noticeable in he higher RPM.

So just a faulty MAF? I called the dealership and they want $440 for a new MAF (just the part).
Looking around it seem Hitachi made the original part AFH60M-27
Is it best to stick with this part? has there been revisions? are the $40 ebay ones any good?

[jnrdavo]

Other option is to give it a good clean, including the connections. There a MAF cleaners at supercheap (I think) that should do the job. Just be very careful as it will have sensors (for airflow etc) on it. Should be a few videos on Youtube to give you the idea :-)

Note that it could still be a boost leak, or PCV, just that unplugging the MAF will 'change' the resulting air coming in to the car..

[boxme2]

Yeah I gave the MAF a good spray with cleaner, worth mentioning the boost went away again even with the MAF disconnected.

I'll try cleaning the connections and give an update.

[jnrdavo]

good luck mate.

[boxme2]

Any suggestions as to what Logs i can run/record?

I recorded boost requested vs boost actual while the issue was occurring and they married up almost exactly, which makes me think it's in some kind of limp mode...

I also recorded these values below while the issue was occurring (no boost):

General: Lambda control value	General: Air mass	General: Air mass_1	Linear oxygen sensors: Lambda actual value	Linear oxygen sensors: Lambda specified value bank 1
2.7	1.9	1.9	-0.9	21.5
-1.2	2	2	-0.9	21.5
-0.8	2	2	-0.9	21.5
3.1	1.9	2	-0.9	21.5
3.1	1.9	2.1	-0.9	21.5
-1.2	2	2	-0.9	21.5
-1.2	2	2	-0.9	21.5
2.7	2	2.1	-0.9	21.5
2.3	1.9	1.9	-0.9	21.5
-2	1.9	1.9	-0.9	21.5
-2	1.9	1.8	-0.9	21.5
1.2	1.9	2	-0.9	21.5
0.8	2	1.9	-0.9	21.5
-3.1	1.9	1.9	-0.9	21.5
-3.5	2	2	-0.9	21.5
0.4	1.9	1.9	-0.9	21.5
0.8	2	2.4	-0.9	21.5
-3.1	2.4	2.4	-0.9	21.5
-2.7	2.3	2.3	-0.9	21.5
1.2	2.2	2.3	-0.9	21.5
1.2	2.1	2.1	-0.9	21.5
-3.1	2.3	2.3	-0.9	21.5
-3.9	2.2	2.2	-0.9	21.5
-0.4	6.5	6.1	-0.9	21.5
-0.8	5.1	4.8	-0.9	21.5
-4.3	6.1	6	-0.9	21.5
-3.9	6.4	6.4	-0.9	21.5
-3.9	7	7.3	-0.9	21.5
0.8	9.6	10.3	-0.9	21.5
0.4	10.9	10.1	-0.9	21.5
-4.7	11.3	11.6	-0.9	21.5
-8.2	11.8	11.4	-0.9	21.5
-6.3	9.8	10.2	-0.9	21.5
-2.3	10.6	9.8	-0.9	21.5
0.4	9.8	10.1	-0.9	21.5
-4.3	10.1	10.1	-0.9	21.5
-3.1	9.8	9.8	-0.9	21.5
1.6	10.2	10	-0.9	21.5
1.6	10.5	10.3	-0.9	21.5
-3.5	10.6	10.7	-0.9	21.5
-5.1	10.2	10.4	-0.9	21.5
-2	10.1	8.9	-0.9	21.5
-2.3	7.3	7.7	-0.9	21.5
-9	7.5	7.6	-0.9	21.5
-10.9	7	6.8	-0.9	21.5
-6.3	6.8	6.6	-0.9	21.5
0	6.1	6.6	-0.9	21.5
0	5.6	5.7	-0.9	21.5
0	5.1	4.7	-0.9	21.5
0	4.6	4.7	-0.9	21.5

And these while the car appeared to working as normal (on boost):

General: Lambda control value	General: Air mass	General : Load	Linear oxygen sensors: Lambda actual value	Linear oxygen sensors: Lambda specified value bank 1
2	4.6	15	-0.8	20.7
2.3	4.7	15	-0.8	20.7
2.3	5.8	18	-0.8	20.7
2.7	9.5	27.1	-0.8	20.7
2.7	9.7	27.1	-0.8	20.7
2.3	9.9	28.6	-0.8	20.7
1.6	7.9	24.8	-0.8	20.7
0.8	7.7	22.6	-0.8	20.7
-1.2	4.7	16.5	-0.8	20.7
-3.1	4.9	15	-0.8	20.7
-5.1	4.8	14.3	-0.8	20.7
-5.9	5	14.3	-0.8	20.7
-4.3	5.3	15.8	-0.8	20.7
-1.2	6.2	17.3	-0.8	20.7
0.4	8.6	21.8	-0.8	20.7
2	10.1	27.8	-0.8	20.7
1.6	11.3	30.1	-0.8	20.7
1.2	11.7	32.3	-0.8	20.7
0.8	15.7	37.6	-0.8	20.7
1.6	17.2	41.4	-0.8	20.7
2	21.2	50.4	-0.8	20.7
1.6	23.5	51.1	-0.8	20.7
-0.8	27	56.4	-0.8	20.7
-0.4	34	65.4	-0.8	20.7
-1.6	39.1	70.7	-0.8	20.7
-4.3	43.5	72.9	-0.8	20.7
-1.2	50.2	79.7	-0.8	20.7
2.7	56.6	86.5	-0.8	20.7
-0.8	72.1	98.5	-0.8	20.7
-0.4	75	103.8	-0.8	20.7
0.4	86.4	112.8	-0.8	20.7
-0.4	88.3	118.8	-0.8	20.7
0.8	90.2	116.5	-0.8	20.7
-0.4	88.3	111.3	-0.8	20.7
-0.8	86.9	106	-0.8	20.7
0	92.6	120.3	-0.8	20.7
-11.3	2.8	15.8	-0.8	20.7
-6.6	7.5	15.8	-0.8	20.7
0.4	12.5	16.5	-0.8	20.7
1.2	14.8	16.5	-0.8	20.7
1.6	14.5	16.5	-0.8	20.7
-3.5	14.5	16.5	-0.8	20.7
-2.7	14.6	16.5	-0.8	20.7
2.3	13.1	16.5	-0.8	20.7
0	12.6	15.8	-0.8	20.7
0	12.9	16.5	-0.8	20.7
0	12.3	16.5	-0.8	20.7
Not sure where to go next...

[jnrdavo]

I'm not much help, sorry, but if you chart these in Excel, you can see some graphical differences... what ever that means! If fuel related, could be the fuel pump..

noboost.JPG
normal_boost.JPG

Looking at the chart, there is no boost (as you know), so what about a PCV and/or boost leak in one of the hoses..

[jnrdavo]

How'd you go, did you get any further?