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Thread: S3 8P Misfire

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    S3 8P Misfire

    Hi guys
    Trolled around almost all the forums trying to look for answers to my symptoms. It happens randomly, but now it's getting worse.

    I get Error P300 and P302.
    Replaced coil packs x 4, plugs x 4. Disconnected battery for 1 hr. Cleaned various plugs in engine bay. Found 1 or 2 small boost leaks in the process. Disconnected MAF sensor and cleaned it. Ran it without MAF sensor, same. I had the BSH delete on, even swapped back to stock, same. Cleaned Forge DV and tested it. I've opened the plastics around the plugs for the coil packs, don't see anything funny. Did logs with fuel pressure's etc... Normal. It shows misfire on the other cylinders too, but nr 2 cylinder is the worst. Battery was replaced recently and charge rate is 13.8 volts, with lights on, and off.

    What happens is on idle u can hear it mis. As you drive and give throttle, even less then 1/4 % it still misses. The only thing thats slightly odd is that my water temps changed more or less when the fault occurred. In traffic and on open road water temps sit at 77 -80 deg C. It's almost feels like its water temp related. When water goes to the normal 88 - 90 it feels fine.
    Car is stage 2+ and this map was working for 6 months prior to this without any problems. So I don't think it's software.

    Any 1 have some ideas ?

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    Rick @ Unicorn Motor Dev.'s Avatar
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    Quite common for this misfire to occur when the thermostat has an issue, which is what it sounds like in your case. Get the thermostat changed so that it sits at a constant 90C and report back.

    Rick
    Unicorn Motor Developments. Bespoke Calibration and Remapping Services
    www.unicornmotordevelopments.com

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    Just an update. Pulled the injectors out and sent them away for testing. Injector 2 & 3 Fail the test.
    I've purchased the thermostat and temp sensor, they going in to fix the temp issue.
    This is what the valves look like at 110 000 Km's with Watermeth for the last 20 000 kms.

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    JamesS4cab's Avatar
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    The picture isnt overly clear - are they bad and is it the meth thats caused the issue??
    "Dont get me wrong. Ugly girls need loving. Just not by me."

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    bmh.01's Avatar
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    They'll all look like that pretty quickly, show me a direct injector petrol that doesn't suffer from inlet valve coking. Wallnut shell blasting is an option but it doesn't really seem to cause massive problems with the tfsi engine unlike others.

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    The Water methanol actually helps in cleaning the valves. I've seen far worse on lower mileage cars.
    Should have her up and running by the weekend. After fixing all the boost and vacuum leaks, new Injectors and a 2nd Water meth nozzle, the car should be hauling again.

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    S3Alex's Avatar
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    Quote Originally Posted by JamesS4cab View Post
    The picture isnt overly clear - are they bad and is it the meth thats caused the issue??
    I think as 18AGTI says,they could be worse,and whilst WMI does help,it won't stop the issue completely,nor will it reverse the coking that happened prior to it's use.

    Mine looked pretty grubby when the engine was stripped down,and AMD said that the RS4s are at least as bad.

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    Got my Beast back. All smiles again.

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    S3Alex's Avatar
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    Quote Originally Posted by I8AGTI View Post
    Got my Beast back. All smiles again.
    Good news.

    All ready for the bank holiday weekend.

    Have a good one!

 

 

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