So I'm headed to the drag strip on Saturday, I open the cutout and do a short WOT run through 3rd, and when I go to hit the brakes, it feels like there's a basketball under the brake pedal. Very little movement in the pedal, and very little stopping power. To make a long crazy story short, the brake pedal is at full stiffness, the boost gauge is zeroed out, and the throttle is sticking. So I've got a vacuum problem, but where would the culprit likely be? I haven't even opened the hood, I was just too disappointed because I thought I was finally going to get some clean runs in at the track and then this, admittedly minor, but really annoying problem crept in. I drove it home and parked it, and haven't thought about it since Saturday afternoon. So, tonight I'll pop the hood and check the vacuum lines, but which one controls all those items?
More then likely it's the big hose that connects to the brake booster. The boost gauge 'T's off of it so your gauge will be dead..... Besides, that is a known problem of our car....it needs to be zip-tied.....twice.....
I agree with Jeff... sounds like the brake booster hose being the culprit. You should ziptie all vac lines and put clamps on others if needed. If you have a boost leak tester available and can do a boost leak test, do one to see where the leak(s) are. That would be the easiest way to find them.
I'll have to check it out tomorrow, lost the daylight already here. So if I lose vacuum there, the brake pedal will stiffen up like that, and the throttle body will stick open? I just had all the brake lines redone by FWD Performance in Houston about a month and a half ago, guess they must have left one loose... good thing it didn't happen at 120mph at the end of the drag strip.
A huge vacuum leak like that will cause some messed up throttle response, so yeah...I'd say that is the issue.
Cool, well there's been a tornado watch all afternoon and evening in Austin here, so I don't have a chance to look at it tonight... hehe. Thanks guys
Good luck with the tornado...I hope one doesn't hit... But, just for your own feel-good-and-fuzzy...If the line does pop off at 120 at a drag strip, you will still be able to stop. The only thing the brake booster does is make it easier.It won't reduce the braking distance, just the input required by you. So next time, just push reeeeeeaaaaallllll hard on the stiff pedal.
Vacuum loss at the brake booster will definitely make the pedal hard (you lost your power brakes) and will affect your throttle. I saw the same thing recently when I replaced the master cylinder on my truck.
the break booster line is in the engine compartment, the shop wouldn't have touched that. it's not their fault, it just happens. most of us have popped that line before, it's not a big deal. i actually have a catipilar clamp on mine, the zip tie popped off lol. the worst was when the big line that runs into the back of the intake manifold popped off....i actually lost breaks on that one.....at 120mph at the end of the track....that sucked.
I agree with all... its the brake booster ive had that pop off a couple times and had to use a clamp instead of zip ties
Haha, yeah I know I still had brake power, but damn I would have pulled the steering wheel off at the strip if I pushed hard enough to stop, or used the handbrake and went Tokyo Dooriftooo on it.
Well, all of the vac lines they replaced were in the engine bay, the lines for the turbo, wga, tb, brake booster, and that re-added the tip sensor line (no idea why). They redid all my lines for me while trying to fix that boost issue I was having on PCM controlled boost. It didn't work and I wound up just sticking a Turbosmart MBC in there and leaving it at 25psi.
Yah, 25, why? It was doing 25psi back in December on PCM controlled boost, but started being very inconsistent and nobody could figure out why, so I went with the MBC and it's been solid, other than the fact that I don't have a low-boost option for 1st and 2nd gear...
I had a vacuum issue once, so I went and purchased a... ...Dyson. Man does that Vacuum SUCK! lol Seriously, did you ever find the problem?
Eh, not yet, it's been raining and the SRT-4 resides out in a covered carport. I'm out of town this weekend so I'll be driving the SRT-8, hopefully have a chance to look at the vac lines Sunday evening when I get back.
