brake light lowers vacuum 50 mmhg?!?
#1
brake light lowers vacuum 50 mmhg?!?
I've asked about this before and got little response, but it's still bothering me so i'm trying again...
My Idle w/ electrical load is 850 rpms (pfc). This only happens with the headlights on. After the AWS is over, there is no "problem" for about 5 - 15 minutes. What I mean is that my vacuum is 410 - 400 mmhg with the headlights on. If I hit my brakes my vacuum hold constant. After the 5 - 15 minutes my vacuum is still 410 - 400 mmhg, but when I hit the brakes, it drops to about 350 - 360 mmhg!?! Again, this doen't happen for the first 15 minutes of driving (after the AWS is off)...
Now with no headlights on, my vacuum is 430 - 420 mmhg, and my headlights only lower it about 10-20 mmhg, so how could my brake light lower it twice as much as this?
Last time when I was getting low vacuum (on and off) it was my airpump (I assume b/c it injects air into the intake durring idle)... I replaced it and everything was fine for 'till now. Is my airpump going again (it's not making any unusual sounds. Is there any other way to tell?), is my battery dying? Maybe my alternator? I have a hyperground ground kit, so I don't think it's b/c of poor grounding...
thanks for any opinions.
-matt
My Idle w/ electrical load is 850 rpms (pfc). This only happens with the headlights on. After the AWS is over, there is no "problem" for about 5 - 15 minutes. What I mean is that my vacuum is 410 - 400 mmhg with the headlights on. If I hit my brakes my vacuum hold constant. After the 5 - 15 minutes my vacuum is still 410 - 400 mmhg, but when I hit the brakes, it drops to about 350 - 360 mmhg!?! Again, this doen't happen for the first 15 minutes of driving (after the AWS is off)...
Now with no headlights on, my vacuum is 430 - 420 mmhg, and my headlights only lower it about 10-20 mmhg, so how could my brake light lower it twice as much as this?
Last time when I was getting low vacuum (on and off) it was my airpump (I assume b/c it injects air into the intake durring idle)... I replaced it and everything was fine for 'till now. Is my airpump going again (it's not making any unusual sounds. Is there any other way to tell?), is my battery dying? Maybe my alternator? I have a hyperground ground kit, so I don't think it's b/c of poor grounding...
thanks for any opinions.
-matt
#2
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Same Thing happens to me as well. It does lower it certain amount and for that time that i hold the brake, seems like my idle lowers as well. It bothers me, but i can live with it.
I think it has something to do with load applied on the Electrical system as the brake lights get turned on.
Not sure though.
I think it has something to do with load applied on the Electrical system as the brake lights get turned on.
Not sure though.
#3
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When I turn on my secondary lights (the lower ones, not fogs) my vacuum drops between half an inch and an inch of vacuum. When the fans come on at idle, it's even worse.
#7
thanks for the replies.
nope, not sure. how is the brake booster vacuum assisted?
no, nothing dims inside or outside the car.
The strange part of the whole thing is that doesn't happen right away... it takes a little while (again, after the AWS is over) before applying the brake has an effect on the vacuum?!
Originally posted by Alex
Are you sure it's the brake lights, and not the vacuum assisted brake booster?
Are you sure it's the brake lights, and not the vacuum assisted brake booster?
Originally posted by 93 R1
Does your dome light dim slightly when you apply the brakes?
Does your dome light dim slightly when you apply the brakes?
The strange part of the whole thing is that doesn't happen right away... it takes a little while (again, after the AWS is over) before applying the brake has an effect on the vacuum?!
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