RPM increases when brake peddle pressed

[tezb]

Just noticed tonight on way home from work that while sitting at a junction with my foot on the brake my rpm was around 1000, when i took my foot of the brake it dropped to normal, put my foot back on the brake and the rpm went back upto 1000.
Is this a vacuum problem with the brake booster, something else or normal ????
If brake vacuum problem any idea of cost, way to test and can i do it myself ????

2004 2.5l

Any help appreciated

 

[PerryGunn]

Is it just increasing rpm because of the increased electrical load associated with the brake lights?

 

[Anonymous]

while sitting at a junction with my foot on the brake

Isn't that what the handbrake is for?

 

[tezb]

i was at a junction ready to pull out, not on a hill

 

[Anonymous]

Foot brake is for slowing down, handbrake for when stopped.

 

[Scooba_Steve]

Handbrake occasionally for slowing down the last few MPH, as per the manual

 

[Bing]

Are you guys seriously debating whether or not the OP should be using the handbrake to slow down or hold the car when stopped, and completely ignoring a legitimate request for assistance ? Jeez...

OP - I don't know the answer, but I'm pretty sure I've seen this problem before on here. Try a search in the e85/86 problems section, or if that doesn't work then put the thread tittle plus 'z4' in Google - if there's an answer on here it's pretty likely to show up near the top of the search, and will cover hits on other sites too.

 

[Number5]

Good shout Bing.

Never noticed it myself, but Ive just searched and found this Tezb:
http://www.z4-forum.com/forum/viewtopic.php?f=3&t=47994&hilit=Revs+braking&start=15

MAF sensor issue according to previous post so hopefully quite simple.

 

[Anonymous]

Are you guys seriously debating whether or not the OP should be using the handbrake to slow down or hold the car when stopped, and completely ignoring a legitimate request for assistance ?

If the brake pedal wasn't being held while stopped this request for assistance would probably not be.

 

[Bing]

It's hardly uncommon behaviour - I do it. And he asked about the engine response to pressing the pedal, when stationary, not whether he should have.... Actually, there's no benefit in this discussion to the OP.

 

[fixit man]

Check the brake servo pipe for leaks and check the (one way)check valve for correct function !

As Bing said it has been covered on here before , do a search for more details

 

[tezb]

any pics of the pipe i should be looking at and where this check valve is ????

Thanks

 

[fixit man]

No pictures , sorry , did a search for you... here's the previous similar fault

http://www.z4-forum.com/forum/viewtopic.php?f=3&t=38786&p=539698&hilit=brake+servo+revs#p539698

The servo is on the R/H side of the engine bay on the firewall , big black cylindrical shaped Vacuum reservoir that the brake reservoir is attached to, see link http://cdn.instructables.com/FAI/DSHF/HTX5L8MF/FAIDSHFHTX5L8MF.LARGE.jpg

 

[SUUNTOBOB]

Are you guys seriously debating whether or not the OP should be using the handbrake to slow down or hold the car when stopped, and completely ignoring a legitimate request for assistance ?

If the brake pedal wasn't being held while stopped this request for assistance would probably not be.

Are you Taco in disguise?

 

[tezb]

how do i remove check valve from servo, is it just pushed on ??????

 

[fixit man]

how do i remove check valve from servo, is it just pushed on ??????

Hi, yes pull off the black pipe, as far as I remember the check valve is in the plastic union fitting on the end of the pipe where it goes into the servo, it can be hard to pull out, be careful not to kink the pipe, clean with some brake cleaner etc.