MSLUB zero'd but still getting insufficient flow codes

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digitalhippie

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	Re: « Reply #15 on: September 03, 2014, 01:00:46 PM »

So I made that change, will see what happens. One thing I noticed, SAI readiness appeared to be set despite the DTC... maybe I just need to disable the DTCs?


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nyet

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #16 on: September 03, 2014, 01:05:50 PM »

No clue! Keep us informed.


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digitalhippie

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #17 on: September 05, 2014, 12:23:16 PM »

Well the MSLBAS change seemed to do it. Codes have not returned, SAI readiness appears to be set.


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metronet

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #18 on: September 13, 2014, 11:54:34 AM »

Quote from: ddillenger on September 01, 2014, 07:32:44 PM

You need to unplug the pump. Insufficient flow works both ways!

Sorry, a newbie question, what does it mean by "Insufficient flow works both ways" and could you share the reason why would disabling MSLUB & MSLBAS get rid of the insufficient air flows for the both banks? (My understanding is these codes were thrown when the front & rear O2 sensor readings have exceeded the upper limits?)

I have been reading a lot on the forums here but can't seem to fully understand the differences between coding out rear O2 sensor vs, disabling SAI. Kindly point me towards the right direction, please?


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k0mpresd

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #19 on: September 13, 2014, 02:25:03 PM »

if you dont know the difference between rear o2s and sai then you may have picked the wrong hobby or you only read the cover of the book.


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metronet

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #20 on: September 13, 2014, 03:22:04 PM »

Quote from: k0mpresd on September 13, 2014, 02:25:03 PM

if you dont know the difference between rear o2s and sai then you may have picked the wrong hobby or you only read the cover of the book.

Thanks k0mpresd. Admittedly I tried to read the PDF "Bosch Motronic ME 7_ ME 7.1_ ME 7.1.1_ ME 7.5 System Strategy" attached in one of the topics but can't seem to figure out on my own so a little bit help is needed Grin

I guess what I am trying to ask here is the pros and cons of "numbing the rear O2s" vs "disabling the SAI/readiness check" on a M/L box.

My 2001 Allroad SAI system is physically deleted and getting the similar codes like digitalhippie:

Code:

Control Module Part Number: 4Z7 907 551 K
  Component and/or Version: 2.7l V6/5VT     G   0001

17831 - Secondary Air Injection System; Bank 1 
            P1423 - 35-00 - Insufficient Flow
17819 - Secondary Air Injection System; Bank 2 
            P1411 - 35-00 - Insufficient Flow

Hence the question whether I should go with option 1 or option 2, or both...?

1: http://s4wiki.com/wiki/Tuning#Rear_O2_Sensors
vs
2: http://s4wiki.com/wiki/Tuning#Secondary_Air_Injection

Most interestingly (or at least to me) is the comment from ddillenger that the insufficient flow works both ways. I think it has something to do with the reason why setting MSLUB/MSLBAS to 0 also requires unplugging the SAI pump electrically to get rid of the insufficient codes (according to the option #2 in s4wiki).

However, I do not understand the reasons behind it.... care to explain? Thanks!


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ddillenger

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #21 on: September 13, 2014, 03:31:40 PM »

Insufficient just means the number is not as expected. Whether that be too low (typically) or too high.

As for SAI vs rear o2. they are different things Tongue

You need SAI.


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metronet

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #22 on: September 13, 2014, 03:43:23 PM »

Quote from: ddillenger on September 13, 2014, 03:31:40 PM

Insufficient just means the number is not as expected. Whether that be too low (typically) or too high.

As for SAI vs rear o2. they are different things Tongue

You need SAI.

Thank you ddillenger. I really appreciate your help. Cheesy

And so just to confirm that I understand it correctly:

- In a simple SAI delete (only) tune; it is good enough to set MSLUB/MSLBAS to 0.
- The ECU will continue to compare the 4 O2 sensors' outputs for pre/post cat efficiency minus the "cold start"? Is this correct? Cheers!


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hopsis

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #23 on: September 14, 2014, 02:41:20 AM »

On a related note, I'm having some trouble trusting the SAI diagnostic in general. About a week ago I replaced the combi-valves with block-off plates in my C5 S6. I have a modified bin with the necessary changes done just waiting for a spare ecu to arrive. However I'm not getting any DTCs after the procedure. The pump is still connected and working. The piping is still there but the air is blown into the engine compartment. No codes.

This weekend I did a timing belt job on a friends '02 S6. Bone stock everything, SAI pump working, no leaks but "insufficient flow" codes and check engine light on. Couldn't figure out why, although I didn't really look into it more deeply.

This babble wasn't mean't to be a question, just thinking out loud. It's quite possible that +10 year old cars (even Germans) do get electrical problems.


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metronet

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	Re: MSLUB zero'd but still getting insufficient flow codes « Reply #24 on: September 14, 2014, 12:33:32 PM »

Quote from: ddillenger on September 13, 2014, 03:31:40 PM

As for SAI vs rear o2. they are different things

I see what you guys are saying now. I thought the rear O2 sensor had something to do with the insufficient codes but clearly they are unrelated.

Finally I am starting to read "SLS 88.150 (Seondary Air Control)" in the translated PDF. Thanks guys! Grin


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