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Thread: sai pump resistor question

  1. #1
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    sai pump resistor question

    sai delete question

    iv found two oval shaped resistors online (witch are stupidly expensive for what it is) that should fit onto the SAI Sensor and N249 electric system but i cant seem to find a larger oval shaped resistor that would go into the power cable that powers the actual sai pump, its the same oval shape as the others just much bigger or should i just go for the much cheaper chinese 10w 330ohm resistors?
    2010 polo gti 9n - stage 2

  2. #2
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    Power = v^2/r = 12x12/330 = 0.43W, so 10w should be ok


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  3. #3
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    leave the pumps power cable open circuit. Its a dumb circuit that isn't ecu monitored. There is no need to burn away at a resister un necessarily. Just unplug and tie it out of the way

  4. #4
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    thanks guys

    i got 10w 330ohm resistor stuff from about 4 guides really dont no what it means or if it will work just happy to try and see what happends iv ordered two oval shaped over priced plug and play resistors they should work, going to wait till im due for a tune before i do this mod!
    2010 polo gti 9n - stage 2

  5. #5
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    The ECU monitors for the presence of the N249 and combi solenoid. It does this by looking for a completed circuit so it wants to see basically the coil resistance of the solenoid. That's what you are simulating when you plug in the resister - jus fooling the ecu into thinking there is still a solenoid there but really its in the bin. It doesn't monitor the SAI pump motor though. Its a higher current output run off a bigger relay and so it can be just left unplugged and the ECU is none the wiser. You can do the N249 right away, there is nothing tune-wise stopping you from doing that. You'll just need to re route a vacuum pipe or two. The SAI/combi will have to wait till a tune goes in that tells the ECU not to look for the changes in exhaust mixture that the SAI system creates though. Even with pump unplugged and solenoid resitered out the ECU as it is now will still be looking to see a really lean mixture at start up (caused by the sai pump blasting air into the exhaust ports) and will bring up a CEL if it doesn't see that after a few goes.

  6. #6
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    can i remove the sai just before the tune, let the cell light come up then just drive in to the workshop and get it tuned out?
    2010 polo gti 9n - stage 2

  7. #7
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    yep. Its just that with the CEL up, you'll have no idea if something else (that may be terminal eg oil pressure) is popping up at the same time too. Your risk to run but yes you can - pretty sure its not a limp mode type of deal if its there for too long.

  8. #8
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    Oil pressure is separate to the ecu. Just a switch and light in the instruments.

  9. #9
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    makes sense my plan was to order the resisters do the mod test drive see what happends, its a shed dweller car so the next drive would be to the garage for a tune
    2010 polo gti 9n - stage 2

  10. #10

    Hey mate, any link to the overpriced resistors? When are you doing the removal? Definitely need to read more about it

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