pressing on brake increases idle

[Guest Anonymous]

a strange phenomenon indeed. i have a '73 tii and the harder i press on the brake pedal, the higher the idle speed goes up. i've checked the one way valve from the intake plenum and that seems ok. i suppose the brake booster is next to look at, but are those things serviceable at all? they seemed sealed up. thanks!

[Guest Anonymous]

URL: http://www.makotoautotrends.com/store-detail.asp?sMaker=3&sModel=&maker=BMW&sku=MAT-UNI-OTT-7XIN-DICL-RO2B-CV12

It is because you pump some air from the intake to the booster, changing the overall mixture. All of my cars with power brake do this (i got many different cars ), even very newer cars do this.

Not a problem at all.

Pat

[Guest Anonymous]

Just sharing some trivia.

[Guest Anonymous]

(nt)

[Guest Anonymous]

My 72tii had the same problem it would go up a couple of hundred rpm's when the brakes were pumped. I replaced that valve and hose coming from the intake plenum and it seemed to fix the problem. I think the main problem I had was the hose (it was rock hard with tiny cracks). Hope this helps.

Sean

[Guest Anonymous]

URL: http://www.makotoautotrends.com/store-detail.asp?sMaker=3&sModel=&maker=BMW&sku=MAT-UNI-OTT-7XIN-DICL-RO2B-CV12

(nt)

[Guest Anonymous]

it's not more than a few hundred rpm, but definitely noticeable -- probably more than normal. i'll try replacing the booster hose to see if it helps matters. thanks for all of your help.