Need help. Possible issue right before track day.

[DavidZ]

I only hear it after the first start up of the day and not again the rest of the day, even after any subsequent start ups; not again until the first start up of the next day.

[sameh]

I have been paying attention since I read your post yesterday. Definitely every morning and after parking it at work for 8-9 hours but shorter periods (grocery shop, gas station,etc) nope and nothing while driving either.

[Seattle S65B40]

Originally Posted by DavidZ

I only hear it after the first start up of the day and not again the rest of the day, even after any subsequent start ups; not again until the first start up of the next day.

same here.

[shendrick]

I only hear my pump pressurizing every morning. Been that way for 2+ years and my M3 is a DD. Your pump is not worthy - get another.

[Erhan]

Thanks guys, appreciate the feedback. I know it is not normal, just wanted to double check just in case. I didn't argue with my SA and the tech at that moment, since it would be pointless. They were already convinced it was OK after changing the broken part.

I don't know what now... I guess I'll just hope it puts the car in limp mode in again so I can get it replaced again... before the next track day, may 19th...

[Erhan]

The car went into limp mode again and I'm at the dealer. Pump was coming on after braking since yesterday and I told them it is not fixed. They didnt listen and here I'm at the dealer again. I'm pissed of course. Why don't techs listen sometimes? If u have the same symptoms before and after the 'fix', chances are issue is still there. Very simple logic.

[JohnnyRoaster]

It sounds more like a leak in the system. I wouldn't be surprised if they broke something during the tech inspection.

I hope it all gets worked out. Not sure if I buy the fact that they just happened to have a pump in stock after saying there were none in the US. Something seems fishy.

[Erhan]

Originally Posted by JohnnyRoaster

It sounds more like a leak in the system. I wouldn't be surprised if they broke something during the tech inspection.

I hope it all gets worked out. Not sure if I buy the fact that they just happened to have a pump in stock after saying there were none in the US. Something seems fishy.

I have the same feeling that they broke something during tech inspection, but there is no point to bring that up and ruin the relationship.

What pisses me off is, I had the same symptoms before and after the fix. It is so obvious that something was still wrong.

Also, yes, new pump appearing in 1 day instead of 2 weeks is VERY suspicious.

[Bubbles]

Have the Tech check the brake vacuum sensor. If the sensor is bad, the ECU thinks there is insufficient vacuum for proper braking which will trigger limp mode. It's part labeled 12 below

[JCtx]

Something's wrong with your braking system OP. I also only hear the pump work once a day, if at all. I'd be extremely surprised a brand new pump is defective in exactly the same way. If you don't have an external leak (easy to check), you have an internal leak somewhere else in the form of a malfunctioning check valve or internal seal somewhere outside the pump housing. Somebody who knows what he's doing needs to check your car. I'd ask to open a 'PUMA' case. Good luck.

By the way, the hydraulic system has nothing to do with the vacuum assist.

[donovan]

I hope your track day comes true.

[Erhan]

Thanks guys. I will talk to my SA and inform him about these points. Next track day is on May 19th. Hopefully this much time will be enough to fix this issue for good.

[Erhan]

I got the car back today. Im told that brake fluid was spilt and damaged the sensor controlling the pump. How this happened was brake fluid reservoir was overfilled and we guess that during autox or spirited driving the fluid get warm and expanded enough to cause spilling.

Car is running fine now. Pump does not run after every brake.