brakes and vacuum

[kamotors]

I was getting on to the highway, so i floored it to merge, then the light turned red so i went to slow down only my brakes were really weak, i slammed them on and still barely stopped, while at the light the check engine light came on and then i gave it just a little gas because that usually gets the CEL to go off, only my brakes were so weak they couldn't even hold the car back.

I pulled into the nearest gas station and checked around to see if there was a leak or if something came unhooked, and it was all fine, i got back in and the car was fine and skidded to a stop this time.when my car is relearning the injectors and and AFM and chip, everytime i touch the brakes the cars idle drops(as if the brakes take too much vacuum or something?)

also if i floor it from a stop it hesitates and then goes really good, but if i give it about 1/2 throttle it takes off really quick and usually spins the tires, this really doesn't make sense to me, do i need a 19lb injectors chip from mark D? I emailed him a few times to see if I could maybe get a deal on a 19lb chip if i sent him the 14lb injector chip i bought from him not too long ago but he hasn't replied.

[jlevie]

An intake leak (or a failing booster) would explain the problem with the brakes, and an intake leak might also explain the CEL. That's the place to start.

[kamotors]

okay i tightened the AFM wheel back to stock( this is the "tuned afm" i bought from lifeiskaos a while ago that the wheel was loosened 2 notches on), and now there is no CEL at all and the car runs a tad less rich and it seemed to not hesitate at WOT as much, I retraced the exact route i drove earlier when the problem happened and the brakes worked but when i was stopped I tried to give it a little gas with the brakes on and the car still just drove forward, my pads are new and the rotors look fine. i went back home and tried to see if the car would go forward if i gave it gas and brake but insted it spun the tires, so this isn't a constant problem it just occasional, i'm definitely thinking its vacuum related, but the car idles great and throttle response is basically instant.

[jlevie]

If when this happens the pedal feels hard, it will be an intake vacuum problem or a fault in the brake booster.

[kamotors]

If when this happens the pedal feels hard, it will be an intake vacuum problem or a fault in the brake booster.

the pedal really doesn't feel very firm, when this is happening. when it first happened i thought i just wasn't pushing hard enough, but it was almost to the floor.

[jlevie]

If the pedal is sinking to the floor, but otherwise feels normal, a leak in the brake system or a failing master cylinder will be the cause.

[Hallen]

If the pedal is sinking to the floor, but otherwise feels normal, a leak in the brake system or a failing master cylinder will be the cause.

Which could also use more vacuum because it is having to provide more assist because of the longer pedal travel and hence the link to vacuum trouble. This is a guess, not a fact.

Bleed the brakes really well first and make sure the fluid is fresh. Then see what happens.