daddy33

iTrader: (5)

When I took the car out for a test drive the brakes sucked! I then bleed the brakes as I opened the valve and had someone step on the pedal as fluid was coming out. I did it about 5-8 times on each wheel side.

Took out for a test drive and seemed to be a little better, but still have step on the pedal HARD and car wont stop as easy. Could this be a vacuum problem? I was thinking of getting a vacuum canister, but then also was told to maybe double check all my braking stuff first before I step into that.

Why do you guys think it has a hard pedal and doesn't stop well?

sailtexas186548

iTrader: (2)

a hard pedal is indicative of a booster issue, which could also be a vacuum issue. Check to make sure the vacuum line to the booster is hooked up and not leaking, and check valve on the booster is working. pull a vacuum on the booster and let the car sit for a few hours, if the pedal does not have at least one easy pump before it gets hard your check valve or booster bladder is likely bad

daddy33

iTrader: (5)

I'll check the lines and see if any leaks. I'm lost though on how you say to pull vacuum and check the booster?

Also I'm not sure if it could effect it, but I have the brass part on the side of the intake open. It's the port that would connect to the fuel purge EVAP which I'm not using.

sailtexas186548

iTrader: (2)

if you have an open port behind the throttle body I'd assume that would be a problem in general...


when the car is just idling is the pedal hard?

use something to pull a vacuum on the booster line (or turn the car on for a minute to do the same), the pedal should be easy to press with the car on. let the car run for 30 seconds and without pressing the brakes shut the car off and wait a few hours, get in the car and press the brakes. the first time you press the brakes the pedal should fee like it did (easy to push) when the car was running, push the pedal again - it should be harder to push, now a third time- even harder to push, now the pedal should be rock hard. If the pedal is hard when the car is running, or on the first push after the car has been sitting turned off it means the booster is not holding vacuum (or receiving vacuum if your motor isn't producing enough) and your check valve or booster bladder is likely broken

daddy33

iTrader: (5)

Well I pressed my brake pedal after its been sitting for a few hours. Pedal kinda felt stiff the first time I pressed it and was the same couple times after.

It's late right now so I'll have to check it out more tomorrow and see if I find anything

xpndbl3

iTrader: (5)

what size cam? Even large cam'd ls motors run power brakes typically, so I'm curious how big it actually is.

ghettocruiser

iTrader: (4)

So a vac port on the intake is open??

That will def cause your vac operated brake booster to not work properly. Cap that off, check that you can only blow through the check valve one way, then take it for a drive. You need to have all the vacuum ports attached to something or closed off.

J.

STREETDEMON

, never leave a port open, go to a parts store and buy an assorted set of rubber vac. caps.

Sick92

Definitely a vacuum leak issue. Cap off anything open, and make sure the tube going to the booster is indeed hooked up to the engine somewhere.

Think of vacuum as negative pressure. All around us in the world, we have atmospheric pressure, which in Illinois is about 14.5psi. The brake booster is two halves separated by a rubber diaphragm. One side (driver side) is filled with atmospheric pressure, the other side (towards from of car) is filled with engine vacuum.

Since one side is negative pressure (vacuum), and one side is positive pressure (14.5), when you push the pedal the vacuum allows atmospheric pressure to overcome the hydraulic pressure in the master FARR easier.

Think of it as one end of the brake booster sucking (vacuum) while the other end is blowing (14.5). We always have atmospheric pressure (14.5).....we don't always have vacuum (negative psi), which is created by our wonderful air pump we call an engine.

Side note: Make sure you pull off that black plastic circle off the brake booster, and blow in the larger end(that was attached to the booster), it should allow you to. Blow into the smaller end(that was attached to a tube) and it should NOT allow you to. This is a vacuum check valve. If it fails, typically you only have an issue when your car isn't running.

daddy33

iTrader: (5)

It's only a mid 230's cam on a 112lsa

Yeah the brass fitting that right on the side of the intake manifold is left open. If I recall, I think I capped it off once and idle was low or close to making car die out.

daddy33

iTrader: (5)

It's weird because my braking was fine with my previous motor. Now that I put this ls1 in, the brakes aren't the same.

I have the hose from the brake booster going to the rear of the intake manifold near the MAP sensor

Orr89RocZ

iTrader: (20)

you can not have a vacuum leak of any kind on the intake for power brakes! Leaving a fitting open on the intake is allowing extra pressure into the manifold and thus screwing up the idle tune.

Cap it off, get the car tuned and it will idle just fine and have good brakes. That cam is not huge by any means...definately big but should still get good brakes once tuned.

daddy33

iTrader: (5)

I'll cap it off and try out the brakes. I won't be able to tune it for a while since its about $400 which I don't have right now, but I did have Mark Roman (a very well know tuner) do a flash tune on it for now.

xpndbl3

iTrader: (5)

Obviously the vacuum leak is the issue, if it is idling too low then have the flash tune looked at, you have other issues. That cam is small in the ls world and no reason why your brakes should have any issue at all.

daddy33

iTrader: (5)

Cool, I hope it's just that then. It idles pretty low around 400-500rpms when I had it capped off. But also have a stock TB and could maybe drill the TB blade hole a tad bit bigger to help.

I'll check in later with the news. Thanks guys

STREETDEMON

instead of drilling out the hole...why not just open the blade up a little more? there is a set screw to do this on the bottom side, and you generally need to open up the blade a little more, with a cam install.

Sick92

This made me lol.
My guess is, it's idling too low because there's not enough air through the tb, when you leave it uncapped, it's helping make up the difference of air the engine needs to produce idle rpm which in turn is making you lose vacuum in all other lines (including brakes). Cap it off, and it cuts off the extra air it needs to idle, set the idle via adjustment, and check your brakes.

I bet they work

ghettocruiser

iTrader: (4)

Yeah... Leaving a vac port open to make a car idle is NOT a good idea. These cars also learn idle. So you could unhook the battery for a while, and then re-start it with everything sealed up. Keep it running with your foot for a little, and see if it'll learn its idle.

I do not recommend drilling the TB hole bigger. My Mark Wilson TB doesnt even have a hole. My FAST 90 TB did...and it was nothing but trouble when it came to getting the driveability nailed down.

If it fails to find idle on its own after a while, start cracking the blade via the adjustment like was already stated. Then save up (should have budgeted a tune with this project ) and get it tuned and she'll run like a top then!

Let us know how the brakes work with that sucker capped off!

J.

Orr89RocZ

iTrader: (20)

Becareful with drilling holes in the TB. Proper way is to play with tune first to see where that is and set desired idle where it needs to be. 500 is too low. 800-900 is much more stable with a cam that size and will give good vacuum signal.

TB may need opened to lower IAC but without knowing what the tune is doing, your making blind changes. Not good.

With vacuum line uncapped its getting extra air but also extra fuel. If using MAP based system, the intake MAP will be higher with a leak like that, so it moves to a higher area in the VE table and thus gives more fuel.

If its MAF only, then thats unmetered air entering the intake and thus leaning out the mixture.

Big cams typically want leaner mixtures and higher timing to stabilize but it could vary.

daddy33

iTrader: (5)

It has been smelling rich lol. Well it doesn't have any convertors also. The flash tune was set with a speed density since I am MAF-less.

I'll cap off that end and adjust the TB if needed. Thanks again!

daddy33

iTrader: (5)

I did this and check valve is good. Capped off the side port on intake and set screw on TB to bring back to idle now. Found the hose I was using wasn't making a good seal on the MAP sensor. Will get that hose replaced tomorrow and check it all out.

STREETDEMON

there should be 2 hose barbs coming off the vacuum port where the map sensor goes, just want to clarify...one smaller one that points to the passenger side, and the large brake booster line.

daddy33

iTrader: (5)

Geez...that's good to know haha. I don't think I have the small line hooked up. Where does that one go to?

STREETDEMON

i'm using it for my HVAC vacuum.

daddy33

iTrader: (5)

I HAVE BREAKS!!! Lol

Plugged the ports that were left open. Snagged a 4th gen check valve and booster hose. Connected everything and no leaks.

Now I almost flew out the windshield when fully pressed the brakes lmao!!

dprest68

iTrader: (1)

LOL. Congrats man! Being able to stop is definitely a good thing!

Sick92

YEY! Congrats man!

daddy33

iTrader: (5)

Thanks guys for the help

ghettocruiser

iTrader: (4)

Glad you got it sorted out man!!

J.