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MAF signal too high. any ideas?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Prawn, Oct 25, 2010.

  1. Prawn
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    Prawn My other car is a MINI!!!!

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    [Oct 25, 2010]
    Gents,

    Thought I’d do a few logs this morning to see what sort of timming pull I’m getting, fairly happy with it really, seeing 1’s and 1.5’s mainly, one 4 on cyl 4 in about 6-7 pulls to redline, but otherwise OK. ambient temp this morning was just 1 degree.


    However, I did have a ‘’MAF signal too high – intermittent’’ fault code before I did the logs, so I cleared this code, then did the logs, and the code was back.

    It’s an AUM engine with a stage 1 map, jetex filter from bill, and a 3’’ DP/decat. Peak airflow this morning was 182-183g/s on most of the runs, suggesting around 228bhp.

    Any thoughts? I’ve heard of MAF too low, but never heard signal too high before!
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  3. s3dave
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    s3dave TFSI Hybrid

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    [Oct 25, 2010]
    log block 2 3rd gear WOT from idle to redline and tell us what the MAF readings are.....maybe its putting out a high value even though it is at idle for example and the MAF and MAP/rpm/tps signals don't correlate?
    Or it has been known to be a bad connector to the maf.....
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  4. bengal
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    bengal Member

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    [Oct 25, 2010]
    If it is connection related you could try dielectric grease in the connector. I solved a wet weather misfire on mine using this stuff and the maf connection can be fixed with it too. Heres a link about it http://forums.tdiclub.com/showthread.php?t=77582&page=7 not sure if im allowed to put links to another forum but here you go anyway i got mine from maplins.
    #3
  5. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    I can tell you what that is duderama...

    Nothing to do with dodgy connections, what it in fact is is that the airflow is exceeding what the map is expecting, or has tables for.

    My Stage 1 used to do this.

    Basically, the map has tables for airflow, and they will go up to x. Say for example x = 180g/s. When you go out and occasionally break through that barrier, to 182-183, the map throws that warning code.

    Airflow is worked out on voltage, x amount of flow past the sensor produces y voltage. The ECU uses the Y value to calculate fuelling. More airflow, the more y will equal, until it goes past the point where it hasn't got data on what to do with any more. Thus, fault code logged.

    Basically, the long and short of what I'm trying to say is it's not broken.
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  6. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    Mine does this all the time too, is it a case of having the map tweaked so that the ecu knows what is going on at all times or is that not possible ??

    It's annoying cause my ESP light will come on everytime the ecu loses the plot
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  7. sportstractor
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    sportstractor Chugger

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    [Oct 25, 2010]
    Bit weird though considering mafs transmit different frequencys rather than variable voltages. Can you fit an s3 maf on there instead?
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  8. Prawn
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    Prawn My other car is a MINI!!!!

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    [Oct 25, 2010]
    so basically, it's so amazingly full of awesomeness that it's too powerful for itself?

    That's good news then! i guess a stage 2 map will have tables for higher values than it's currently making.

    Airflow has increased massively since it was first mapped, came back from Rtech making about 168g/s with a few issues, I added the jetex filter, 3'' DP/decat, N249 bypass and PCV removal and it's now up at 183g/s most days, so a decent improvement since it was first mapped.
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  9. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    ECU just uses a digital volt/ohm meter (dvom) that can measure frequency. Same principle.
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  10. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    Thats what I would say the issue is dude. :thumbsup:
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  11. Prawn
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    Prawn My other car is a MINI!!!!

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    [Oct 25, 2010]
    Mine puts the ESP light on when it see's exceptionally high flows too! mainly happens when giving it death on a very cold morning.
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  12. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    You can read so many things on here, didn't know whether is was a good thing or not, lol

    Mine tends to do it between 3-4000rpm when I'm accelerating hard in 4th,5th or 6th...
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  13. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    Which would be max load....
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  14. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    Welly, could the map be adjusted to prevent this happening ??

    I know when mike mapped the car I was running usual super unleaded and mike told me he had mapped it to run on V-power, ecu may not of adapted properly I assume...
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  15. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    Only by them I would imagine. Would be worth getting in touch with them and asking the question.

    The fuel side of being mapped to run on V Power would most likely be the ignition timing advance. You can add more when you run better fuel.
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  16. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    Just spoke to Mike at Jabba and he suspects a boost leak :(

    Apparently if I get the maf reading when stationary and hold the revs at 3000rpm I should see a reading of 10g/s, any deviation of 0.5 is fine, any more of a deviation would indicate either a boost leak or electrical problem, though he suspects a boost leak...

    Asking where are the common problem leaks I was told to check around the intercooler pipes, they can come lose or split and air will escape throwing out my maf readings...

    If I can't find a fault then he said to bring the car up and he'll check it over for me...
    Last edited: Oct 25, 2010
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  17. Welly
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    Welly VX220 SC Driver :)

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    [Oct 25, 2010]
    Result!
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  18. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    I've been wanting to pop up and see him for a while to make sure the car is still running sweet, Friday it is :)
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  19. Prawn
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    Prawn My other car is a MINI!!!!

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    [Oct 25, 2010]
    interesting test, I'll try that in a mo when I leave work
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  20. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    That's what I thought, I presume that would work on all remapped 1.8t's, if that's the case then it would be a nice quick simple way to see if you have a boost leak...
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  21. Prawn
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    Prawn My other car is a MINI!!!!

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    [Oct 25, 2010]
    done the test, bang on 10g/s.

    Fault code seems to come up regularly now, although I've not had the ESP light. Going to give it a blast to work again tomorrow and see if the code comes back without seeing the light
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  22. s3dave
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    s3dave TFSI Hybrid

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    [Oct 25, 2010]
    As Said before check your connector, they must be one of the more frequented parts of the car and the spades can go big in the connector from the constant removing of it,
    ive had it on a mk4 golf i think it was the green wire..... replaced the connector and it was fine....
    #21
  23. Essflee
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    Essflee Well-Known Member

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    [Oct 25, 2010]
    Nice one !! :)
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  24. Imteyaz
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    Imteyaz 6th Gear

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    [Oct 25, 2010]
    Speak to Nick about this Prawn, I got this after having it mapped (DTC 16487 - Mass Airflow Sensor - G70 Signal too high), Nick tweaked the map and it's not returned since.

    He explained it similar to what Welly said earlier - which is waaaaay too complicated for me to understand, all I know is it's stopped doing it now. Heard Nick muttering something about tables, could have been the wooden 4 legged variety for all I care :p...
    #23

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