Pulsing throttle and brake pedal

[dbp510]

2018 audi rs3

I feel like every time i make a post, it's about some new issue.

Last night, I took the car out for a joy ride and drove it decently hard. When i got back to the garage, i noticed the brake pedal pulsing or shuttering on its own. This is not a warped roter as it does it while sitting still and as well as moving.

The throttle feels very similar while the brake is doing the same thing, too.

I'm wondering if i may have popped a vacuum line or if i might have broken some mount that holds something sturdy that is now just shaking.

Or possibly a master/slave cylinder?

I'm not entirely sure about the throttle, though. Since it's doing something very similar. Are there any electronics that control both the pedals?

Thanks for any input.



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[NapalmEnema]

Start simple, and since you don't know the history on the car super well, assume it wasn't taken care of to the best on all things.

It sounds like the previous owner never changed / or bled, the brake fluid. It sounds like you have air bubbles in the brake fluid / it's old and needs to be changed out. I'd start there and see how things are after that. Also if you bleed your brakes you can see if there were air bubbles when you do.

Start small imo and change fluids if you're not sure if they have been changed in a while.

[dbp510]

Start simple, and since you don't know the history on the car super well, assume it wasn't taken care of to the best on all things.

It sounds like the previous owner never changed / or bled, the brake fluid. It sounds like you have air bubbles in the brake fluid / it's old and needs to be changed out. I'd start there and see how things are after that. Also if you bleed your brakes you can see if there were air bubbles when you do.

Start small imo and change fluids if you're not sure if they have been changed in a while.

That is not a bad idea. I'll swap out the fluids, and I'm going to bring it in to the dealer and have them do a ppi on it. Although how do dealers feel about their cars being modded? It isn't under warranty anymore, so I'm not worried about that.

I'm going to throw the car on my lift when i get back into town and do a very thorough inspection myself of the bottom side of this car.

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[NapalmEnema]

That is not a bad idea. I'll swap out the fluids, and I'm going to bring it in to the dealer and have them do a ppi on it. Although how do dealers feel about their cars being modded? It isn't under warranty anymore, so I'm not worried about that.

I'm going to throw the car on my lift when i get back into town and do a very thorough inspection myself of the bottom side of this car.

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They shouldn't care, but if you're concerned you could take it to a speed shop that works on Audi's instead. Another option is to just download the full service manual for your car and tackle it yourself so you know it's done right. If you have a lift at your house you seem set to wrench, so personally I'd get a bleeder setup if you don't have one and start with that and check things out for yourself. (you can get a 1 day membership to the site and download everything for your car) I think the gas pedal reacting when the brake does is more that the brake is just causing the vibration so you feel it in both pedals.

[dbp510]

They shouldn't care, but if you're concerned you could take it to a speed shop that works on Audi's instead. Another option is to just download the full service manual for your car and tackle it yourself so you know it's done right. If you have a lift at your house you seem set to wrench, so personally I'd get a bleeder setup if you don't have one and start with that and check things out for yourself. (you can get a 1 day membership to the site and download everything for your car) I think the gas pedal reacting when the brake does is more that the brake is just causing the vibration so you feel it in both pedals.

Yeah, i feel it in both. I'm worried i may have damaged something else. What's weird is driving it all day today it felt normal except when coming to a stop at a few stop signs. I would pull up and stop, and the pedals would just vibrate. If i shut the car off, it would go away, or if i started moving again, it would last a while, then randomly disappear. I tried to see if it may be gearing related, and it does seem to feel like it's pulsing/vibrating the most in 5th gear, but i may just be over reacting cause im looking for the issue.

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[RS3TP]

Could it be the motor mount

[dbp510]

Could it be the motor mount

It very well could be. It happened after a really hard pull.

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[RS3TP]

sounds to me like the motor is moving around and causing the throttle and brake pedal to pulse

[TheContrarian]

sounds to me like the motor is moving around and causing the throttle and brake pedal to pulse

Agree

[dbp510]

sounds to me like the motor is moving around and causing the throttle and brake pedal to pulse

How common are broken motor mounts? I'll probably order a set regardless of them being broken or not.

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[A418t81]

Does the car have an intake/turbo inlet? If so, those can get out of alignment and intake tube hit the brake booster which leads to vibration of the firewall which you feel in the throttle and brake pedal.

[dbp510]

Does the car have an intake/turbo inlet? If so, those can get out of alignment and intake tube hit the brake booster which leads to vibration of the firewall which you feel in the throttle and brake pedal.

It does indeed! Holy hell i never thought of this. I will go check it right now

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[dbp510]

Does the car have an intake/turbo inlet? If so, those can get out of alignment and intake tube hit the brake booster which leads to vibration of the firewall which you feel in the throttle and brake pedal.

You wee 100% correct. Thank you a ton. Some of the stupidest shit can be the most annoying. It somehow popped out and cause it to all shove backwards.

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[A418t81]

Awesome. This used to be a common occurrence back in the day. I was surprised to read the thread and not see anything about the intake. Congrats 👍

[NapalmEnema]

You wee 100% correct. Thank you a ton. Some of the stupidest shit can be the most annoying. It somehow popped out and cause it to all shove backwards.

20221128_103714.jpg20221128_103718.jpg20221128_103722.jpg

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SWEET another easy fix! So happy for you man, glad it was something minor. I'm very new to the RS3 platform so don't know some of the nuances that's an interesting one to remember!!!

[signde]

glad OP found an easy fix. this is a reminder why every time i take my car in for service i have them check the inlet and intake to make sure it is not loose.

[RS3TP]

Now you can sleep at night ... you need a cold beer to celebrate .. or two

[z06user]

Glad I found this thread! I was getting a strange pedal feeling in the brake after installing my IE Carbon fiber intake on my 24 RS3... Inspected it just now after reading this, the inlet tube was making contact with the reservoir cap like in OP's photo. Quickly readjusted it and the vibration is gone.