Weak pedal and braking distance fixed with intake cleaning?

Hi all.

After I replaced the crappy aftermarket intake with a stock OEM system and cleaned out the whole intake manifold I saw a much improved brake feel, shortened braking distance, and better pedal feel on my 6th gen Accord.

I am trying to understand why the pedal is so good on my 6th gen accord. I feel like the brakes on my sports car are wooden in comparison, and I can't believe it!

On the Nissan, I put street performance OEM spec pads and rotors on the hubs. Installed stainless brake lines. Had the lines PROFESSIONALLY BLED by the Nissan dealer and a local performance shop. Still can't get the same easy press to stop on a dime like the Honda.

I'm wondering if it also has something to do with the intake of my Nissan? Can anyone recommend areas to check that aren't the normal areas of concern (not bleeding the lines, replacing the fluid, or replacing rotors & pads). Other people with my set up have much lesser braking distances and much less pedal effort.

Could it be a clogged hose or intake runner or something? Stock intake on the Nissan for 80k miles so far. Car is 8 years old.

Thanks for reading, hopefully you can help me find a solution.


The thread where I was having running issues for the Honda that solved my braking problems: http://www.6thgenaccord.com/forums/showthread.php?p=1090708#post1090708

Well, the first thing to do is check your brake booster for vacuum. If something has changed the vacuum source (should be at the manifold behind the throttle body) for the brake booster, that will definitely decrease the available braking. Also, there's a one-way check valve for the brake booster. This is supposed to mean that the brake booster will be under the maximum vacuum. It should be a minimum of about 22 inHg if your check valve is healthy, and you've closed the throttle while the RPM is up. It should remain at this level (more or less) even if the car is parked for a few hours. If the vacuum level is lower, then there is a problem with either the brake booster, or the check valve.

Some performance brake pads aren't very good when they're cold. They can be designed to perform best when hot, this is typical for racing applications, though not so much for street. Even some which are labelled for street are just ok when cold, (as opposed to a true race pad which suck when cold) but do much better when hot. Check the specifications for the pads that you use. The Porterfield street pads are popular with the Supra guys, but I wouldn't know what's available for an unspecified Nissan. Yes, a clogged hose COULD have something to do with it, however how a vacuum hose could get clogged is a puzzle. There would have to be something wrong with the brake booster, IMO.

As to what an intake swap could have to do with it... Not sure, unless it somehow affected either IACV or interfered with the vacuum line to the brake booster. That's really the only connection that the braking system should have to the engine. There will be an electronic connection to the ECU for ABS systems, however that should have nothing whatsoever to do with the brake system. Brake systems are generally designed to be as direct and mechanical as possible, so that they will work as expected even if something catastrophic happens to your electronics, though electric power assist systems are starting to appear on some models

Thanks for the detailed reply. I will have to check the pressure put out by the booster as you've mentioned.

It's a Nissan 350GT or known as the Infiniti G35 coupe in the United States.

They are centric general pads that were made for a daily driver. Not the economy ones. Bought them on Rockauto.

Cleaning the IACV and replacing the stock air intake system made the Honda a car with pretty much a brand new braking system.

Is there a way to "clean out the line" by removing it and running something like carb cleaner through it?