Brakes = RPM drop?

[S13s Lost Illusion]

I'm getting this problem in my car where, when I press my brakes it drops my RPMs instead of raising it at idle, ie. 700 RPM to 550-600 RPM.

I don't understand what's going on. I don't know much about the theory behind the mechanics of the cars, so I can't really troubleshoot myself.

Can someone tell what the problem is?

[Silvia007]

Does the RPM drop when you press the brake at stand still? Or does it only do it when you are moving? It could be a power problem... I notice that when I play loud music and I'm at idle, everytime the sub produces really low frequencies my rpm would drop to about 500 also... this is because I don't have a capacitor... oh well... you could try new battery/alternator. My theory behind this is when you step on the brakes the lights come on which chews up power quicker from a sour battery.

[Exar-Kun]

is it going back up right afterwards, or stayling low? mine goes low for a second then pops back up to normal..-chet

[MadSideways]

It sounds like a vaccum leak....check your hoses for cracks or loose clamps...particularly the brake booster hoses...

[GodDrivesA240sx]

It sounds like a vaccum leak....check your hoses for cracks or loose clamps...particularly the brake booster hoses...

[91nis240]

nah its normal, 240's have all kinds of little rpm fluctutions when idling, my rpm's drop when i press the break and even when i open my door lol crazy.

[S13s Lost Illusion]

nah its normal, 240's have all kinds of little rpm fluctutions when idling, my rpm's drop when i press the break and even when i open my door lol crazy.

LOL

thanks for the Info, makes me feel much more relaxed.And I'll check my lines for vacuum leaks also.

[4cefed]

I use ether to check for vacuum leaks. I haven't even set anything on fire!