Brakes affecting RPMs, WTF?
#1
Full Member
Thread Starter
Join Date: Apr 2002
Location: Corpus Christi, TX
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Brakes affecting RPMs, WTF?
I noticed while sitting a stoplight the other night that when I depress the brake pedal, the engine is noticeably affected. I can hear the engine change and the tach drops about 150-200 RPM. Why in the world would pressing the brakes affect the engine?
#3
Rx-hippie
iTrader: (1)
Join Date: Sep 2003
Location: Torrance CA
Posts: 2,076
Likes: 0
Received 0 Likes
on
0 Posts
BAC should alow more air flow when putting more load on the car.. ie amps being taken from alt when putting brake light.. Mine goes down when I hit the brake at a stop.. but quickly go back up normal.. If your rpms just stay down when hitting the brakes.. maybe your BAC is out.
#6
I'm a boost creep...
Join Date: Jan 2002
Location: Auckland, New Zealand
Posts: 15,608
Likes: 0
Received 8 Likes
on
8 Posts
The brake lights normally draw about 11-12A, which will put quite a strain on a tired alternator and/or battery.
The BAC (bypass air control) valve is the main idle control valve. The ECU uses it to compensate for extra loads on the engine from the alternator and A/C.
The BAC (bypass air control) valve is the main idle control valve. The ECU uses it to compensate for extra loads on the engine from the alternator and A/C.
#7
Rotary Enthusiast
Join Date: Dec 2002
Location: Darwin, NT, Australia
Posts: 1,228
Likes: 0
Received 0 Likes
on
0 Posts
Having no BAC on my car I feel I should comment on this.
The current drain on the alt. that the brake lights draw will NOT affect your idle(considerably).
I feel that the only reason you might experience idle difficulties is if there is a Vacume leak.
The current drain on the alt. that the brake lights draw will NOT affect your idle(considerably).
I feel that the only reason you might experience idle difficulties is if there is a Vacume leak.
Trending Topics
#11
Rotary Enthusiast
iTrader: (25)
Join Date: Sep 2003
Location: Melbourne, FL
Posts: 1,440
Likes: 0
Received 0 Likes
on
0 Posts
my brake light is on all the time until i shift pass 4k rpms, but when i stop in a light it will come up... i resolder teh point sin the idiot lights and it still does it... it has new battery, new alternator, new belts... it just started doign this about 3 - 4 weeks ago... could it be teh BAC? the amps on the bac read okey... maybe i should take off the home made cartton box gasket i ghetto made... and use rtv
#12
Junior Member
Join Date: Jun 2002
Location: CA
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
Mine does the same but I didn't notice if it stay low (rpm) if my feet keep on the brake. I not put the gear in N and use the hand brake at the light, that helps. I will see tomorrow have my AC on and keep my feet on the brake see if the RPM stay low. If it stay low it could be bad BAC right?!
Thread
Thread Starter
Forum
Replies
Last Post
rgordon1979
3rd Generation Specific (1993-2002)
40
03-15-22 12:04 PM