E303 vacuum?
 

I just got my new motor back...car runs awesome...BUT the brakes are horrible. As far as I can see, there's no vacuum leak. I dont have a gauge so I havent checked my vacuum yet, but I'm running the E303 cam. The brakes are horrible...I mean they were pretty bad before the motor swap but now they're nearly unbearable. If I'm not easy on the braking and accelerating, my brake pedal goes rock solid and the car will barely stop. I blew through a stop sign by about 5 feet because I lost all pedal.

Is this kind of vacuum loss normal for an E cam?? Sounds pretty odd to me since the cam is so mild. BUT, by the way, it lopes like CRAZY for some reason....I could barely believe it was an E when I cranked it up. Only reason I do think it's an E cam is my gas mileage. :rolleyes:

sounds like something is wrong or it,s not an e cam
.......i have an e cam in mine ,didn't even notice any difference in the brakes ...they still work fine

the idle in mine is fairly lopy ,the e cam kind gives it a cam type idle but its not really lopy like a high lift cam ,it idles pretty good and still has pretty good vacuum

......i'm thinking that there might be something else causing your braking weakness .....aside from the e-cam ,i've seen some pretty high lift cams that still have enough vacuum to operate the brakes .......your combo would determine what your vacuum levels are ,depending on the combo ,it all effects the vacuum ....with my combo below i still get around 20psi at idle but it can differ from combo to combo

Re: E303 vacuum?
 

I'd either buy a vacuum guage (the're really cheap) or rent or borrow one and get a reading instead of guessing. That really lopey idle comes in large part from overlap and overlap is what causes a large percentage of vacuum loss. So it stands to reason if you have a really lopey cam you aren't gonna have much idle vacuum. Then again there are many other things that could be causing your problem, but i'd say first step is to find out what your idle vacuum is.

my car made too much vacuum with the e-cam, i have a vacuum leak right now just so it will idle.

UPDATE: I borrowed my friend's vacuum gauge today and checked my vacuum on a warm engine with a normal idle. It bounced between 10 and 12 HG's of vacuum, occasionally dipping down to 9. I think I've got a serious vacuum leak somewhere, but my hoses are all intact and I can't HEAR any sort of hissing noise or anything...my only guess is maybe a leaking intake manifold gasket or there's something wrong with the diaphragm or seal in the EGR valve?

What injectors are you running and what is the fuel pressure? Does the car smell like it is running rich? If it is running rich it will show low vacuum. Check all your plug wires and make sure they are tight and that a cylinder isnt loading up. Rich=low vacuum=crappy brakes

ALL factory fuel system. YES, it is running rich. It STINKS. Plug wires are in decent shape. They suck..but they have no major issues.

Running rich is showing low vacuum. There probably isnt a vacuum leak, a vacuum leak will make it run leaner. I would blame the problem on 2 things. 1, bad injector(s) that could be hanging open or 2, bad mass air. When my motor was first together, there was a trick flow cam in it. I than swapped in a huge .603 lift cam that was custom ground for a stroked 351, than went in a f303 cam and then went back to the trick flow cam. I had the same problem that you are having, it was running pig rich. Wouldnt idle right, had low vacuum, i put new injectors in with no change, spent many hours looking for vacuum leaks, took timing cover off to check to make sure gear drive gears were good, put every new sensor in except for one, a mass air. Put a new mass air in a everything was solved.

Hmm....well my idle is pretty good, it only bounces by like 50 rpms max. Once I put the car in gear, the idle smooths out considerably, which is contrary to a vacuum leak...the idle doesn't rocket up either. It's got brand new injectors...19 lb-ers....but the MAF is still the original. It's not throwing any codes or anything so I'd hate to replace it because they're so damn expensive.

Are Ford MAF's like GM MAF's in that the car will still run if you disconnect it? With GM MAF's, a test to see if the MAF is crap is if you disconnect it, generally the car will idle better or stop stalling, etc.

Let me know if it is the MAF b/c I currently can't get my car to idle and it runs very rich. I have a tfs stage one cam with 1.7 lifters and I got about 7-9 inches of vacum (about 20 cm)

You can disconnect it with it running and it should change alot, idle all weird and want to die, you plug it back in and it is better again than you know it is working. I would try one off of another car just to check.

One other thing that can give you low vacuum is if you have adjustable rocker arms they may be to tight.

I had an e-cam and had a vacuum reading around 11, and my brakes worked great.

Hmm....let me rephrase. My brakes DID seem to gain a little bit of stopping power as I put miles on the motor and loosened it up. They are now bearable...almost normal. BUT, in emergency braking situations, they're very underpowered. Which is why I'm going to buy a vacuum canister. I'd kick my idle up to 900 or so so I'd get more like 15 on the vacuum...but that would eliminate the choppiness of the cam all together...which I really like, so, that's out of the question!

well, i didnt read this entire post, but if your sure your vacuum is the cause of your poor brake performance and not something else, then just install a canister like you said, but you really shouldnt be having any problems, even with a reading of 11.

Well my brake performance is crap to begin with....the pedal doesn't grab until down far and it can't stop like it used to..I can stand on them and they won't ever lock up. And sometimes when I hit the brakes, there's a loud pop and the pedal goes to the floor..then when I release it the car will barely move for a second, and then another pop and it jerks forward. I figure either a sticking caliper or maybe something wrong with the brake line...feels like it's the driver's side.

sounds like your due for a master cylinder .......the above discription is pretty typical of your master cylinder not functioning properly

That's exactly what I didn't want to hear...:mad: