Why do people use check valves to bleed off boost instead of putting just one inline to the map sensor and when boost is coming, it will simply block it. When put inline, it should simply let vaccum conditions remain and when boost conditions occur, it should just close up and not let any boost come through with vaccum at 0 like at wot on n/a cars. Or does it simply not work like this?

 

I asked the same question and then I tried it. By putting the check valve in line you'll be running full vaccuum in the portion of the line between the check valve and the MAP 100% of the time since the check valve only allows for one way flow. The air can never go back into that portion of the line.

 

Yes, I guess your right. Now it makes sense to me. Because of the vacuum, when the check valve closes the vacuum will still be in the line from check valve to MAP sensor and not give good readings to it maybe causing a lean condition?

 

Yup, it'll run like sheeit, as in lean. I've heard you can solve this by poking a little hole in the vacuum line between the valve and the MAP so as to relieve the vacuum. But I never had any luck doing this.

 

Thats a very good post bud.

I have a brake check valve bleening off boost before my MAP sensor. Maybe I should rethink this. What, just take the Check valve out and put in a series of fish tank check valves?

 

i had it w/ the hole in. it ran fine...or so i thought. when i put a missing link in, it was like a new car. soooo much smoother and no more backfiring when shifting sometimes. so it works..just like crap.

 

My car seems to run fine with the check valve I have set up. I have the valve off the end of a t so it bleeds to boost on the way to the MAP. Should I maybe swtich to fish tank valves? I'm curious about this leaning out problem with only a single brake check valve to bleed boost.

Does anyone have any more info on this?

 

hehe, aren't ya glad I was there to let you try the ML out :D

 

the hole between the check valve and the map is there because the valve works more on airflow and not pressure. there has to be some place for the pressure that does make it thru the valve to go. otherwise both sides of the valve will pressurize and you'll trip the check engine light. i've had the best success with holes approximately .080 inch in diameter. or you could just get a hondata and solve all your problems.

 

Well this is the check valve setup I'm talking about.

I have not had a problem with it, that I know of. Unless this would cause some leaning out?



[Modified by Hybrid, 5:10 PM 8/7/2002]

 

those fittings looks like their corroding pretty bad......salt on the road?

 

Lots of salt. In the past the car was winter driven. I'm located in atlantic Canada and in the winter time they give it to the salt.

So can anyone tell me if I should change my map/check valve set up? Or if you see any problems with it?