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  1. #1
    Established Member Two Rings rzyao's Avatar
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    Jan 05 2020
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    Massachusetts

    Will S4 2.7t injectors fit in a 1.8t?

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    I know this has been asked before but I can't find any good definitive answers. I recently installed an F21, and am finding out that my injectors are exceeding 100% duty cycle at WOT at wastegate pressure causing me to lean out, so I need new injectors. My friend has some spare 550cc S4 injectors with wiring harness adapters, would they fit into my fuel rail? Do I need spacers or anything like that?

  2. #2
    Veteran Member Four Rings Cybersombosis's Avatar
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    Nov 13 2009
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    Victoria, B.C., Canada

    Depends if the injectors are long or short. If he didn’t need spacers then they will fit without spacers. You will need to get your car tuned to run those injectors or in general as you’ve changed a major part of your car. Do you have a tuner that you are using or just slapped the F21 in?
    2001.5 Audi A4 1.8TQMS - Brilliant Black on Black Onyx Sport Cloth
    Motoza Hybrid K04 Tune, FT F4-H, Bosch EV14 550cc, AEM Water/Meth Injection, Majesty FMIC, SSAC Cat Back Exhaust, Podi Boost Gauge, ATP Test Pipe, K&N air filter, HID fogs, eBay short shifter, Aero wiper kit, Eibach Pro-Kit springs, 18” B6 Ultrasport, Firestone Indy 500.
    2001 Audi S4 SRM K24 RS6 build

  3. #3
    Established Member Two Rings rzyao's Avatar
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    Jan 05 2020
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    Massachusetts

    Quote Originally Posted by Cybersombosis View Post
    Depends if the injectors are long or short. If he didn’t need spacers then they will fit without spacers. You will need to get your car tuned to run those injectors or in general as you’ve changed a major part of your car. Do you have a tuner that you are using or just slapped the F21 in?
    He hasn't run them in the car yet, they came with a bunch of parts he got to do a motor build but he's getting 1000cc injectors so these are just spares. If they're the wrong size, would spacers make them work fine? I guess I'm just asking if the S4 fuel rail is the exact same fitment as the A4 fuel rail since I've seen people say both yes and no

    I'm not super worried about the tuning aspect as I've been becoming more familiar with editing maps, I've had to learn a lot to get my 3 inch MAF conversion running right. To my knowledge I can just scale KRKTE to fit the injectors and make small adjustments until my trims and WOT AFR are good

  4. #4
    Veteran Member Four Rings Cybersombosis's Avatar
    Join Date
    Nov 13 2009
    AZ Member #
    50676
    Location
    Victoria, B.C., Canada

    Just compare them to the ones in your car or post up a pic of them. Can’t really answer until we see them. My 550’s fit without spacers as they are the shorter Bosch injector.
    2001.5 Audi A4 1.8TQMS - Brilliant Black on Black Onyx Sport Cloth
    Motoza Hybrid K04 Tune, FT F4-H, Bosch EV14 550cc, AEM Water/Meth Injection, Majesty FMIC, SSAC Cat Back Exhaust, Podi Boost Gauge, ATP Test Pipe, K&N air filter, HID fogs, eBay short shifter, Aero wiper kit, Eibach Pro-Kit springs, 18” B6 Ultrasport, Firestone Indy 500.
    2001 Audi S4 SRM K24 RS6 build

  5. #5
    Senior Member Two Rings
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    Oct 15 2020
    AZ Member #
    570003
    Location
    Eagle River, Alaska

    Quote Originally Posted by rzyao View Post
    I'm not super worried about the tuning aspect as I've been becoming more familiar with editing maps, I've had to learn a lot to get my 3 inch MAF conversion running right. To my knowledge I can just scale KRKTE to fit the injectors and make small adjustments until my trims and WOT AFR are good
    When changing injectors, you should also change maps for;
    TVUB - Injector offset dependent on voltage
    KVB - fuel consumption constant for display (if you want dash trip computer to calculate correct MPG and distance to empty with new injectors)
    TEMIN - minimum injector on time (used for closed throttle de-acceleration). Might still work with the stock injector map value but should be shortened to match to greater fuel volume of larger injectors.

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