Why would that happen ?

Just read this ill check it out.... https://www.rx7club.com/showthread.p...ip+idle+brakes

 

its normal for the engine to dip slightly when the breaks are pressed since theres load being put on the engine. its the same as having a auto be put D the idle drops unless its a FI car in which its compensated with the engine increases rpm in order to compensate for the load. i on the other hand have no idea why the engine would stall unless theirs a vacuum leak

 

Voltage drop also since taillight goes on.

 

Unless you have most of the other accessories on in the car (heater or A/C on high, radio cranked, headlights on high beams) the brake lights coming on should not create enough of a voltage drop to even affect the engine idle. The brake lights should only draw about 5-6 amps depending on your bulbs.

Usually, a vacuum leak wouldn't cause the engine to stall unless its a huge vacuum leak.

 

he's not stalling hes just experiencing the normal rpm drop that comes with brake use at idle.

 

Oh I see, I must have misread that. Either way, electrical load from the brakes being applied should not cause RPM drop. A good system in general should not cause the engine RPM to drop. This doesn't happen on my 79, though it did on my 82. It's possible that old wiring is causing a higher voltage drop when the brake lights come on, or there is a slight problem with the brake booster. I've never seen rpm drops higher than 50-100 rpm max though so I would be a bit concerned if my rpm dropped a considerable amount.

 

yep my sentiments exactly. anything more than 50-100 would be worrysome. i'd say its vid time LOL