Brake pedal goes stiff under heavy braking, no ABS engagement?

[ilikerice]

If Cranky is autocrossing, yea, he is definitely getting in the ABS zone sometimes. Everyday driving, probably not. Says it happens at crowns on parking lots, so its probably an autocross event.

[CrankyOldMan]

Originally Posted by ArmstrongRacing

Is the check valve still in your brake booster line? And in the correct flow direction?

If there's a check valve, it's not in the section that I replaced. The Blitz kit only extends the connection from the brake booster to the intake plenum, which is just a hose.

Originally Posted by CoryM

Your guess of a blocked vacuum line is probably correct. It's possible to get some erratic pedal effort due to a failing booster, but that's usually minor. Silly question, but is your vacuum line connected before the blower? Otherwise if you are making boost your vacuum stuff will not be working well .

Abs is likely not doing anything because you aren't able to brake hard enough to cause lock-up.

Yup, the vacuum line from the top of the engine block (next to the fuel rail) goes directly behind the TB.

Originally Posted by ilikerice

If Cranky is autocrossing, yea, he is definitely getting in the ABS zone sometimes. Everyday driving, probably not. Says it happens at crowns on parking lots, so its probably an autocross event.

Apologies, I assumed posting in the track/racing/autoX forum implied it was under performance conditions. =) Yes, it's been in parking lots.

I've recently attended a car control clinic and one of the exercises involved getting into ABS on dry, flat pavement--aka straight line braking. Got into the ABS 3 of the 4 times, so it shouldn't be an issue with "leftover" boost getting into the brake booster on rapid transition from WOT to brake. That just leads me back to the downhill slope idea...