check valves? what kind?
 

Hey,
I need some help here, I've got a T25 turbo and I am doing a turbo on my civic sohc like most of you homies out there. Anyways, I'm going with a vortech 6:1 fmu and I need to know what kind of check valves I need to put in the line between my boost gauge and my map sensor intake so the CEL doesn't show up. Do you know where I can buy the 3 valves already on a line or what type of check valves I am supposed to buy?
Also, does anyone know if the O2 sensors are the same on the SI as on like the VX because I need to change mine out when I go to put the turbo on. Are all SOHC civic O2 sensors the same?
Thanks in advance for any help!

Re:check valves? what kind?
 

Go to any automotive store, they will have 1way check valves, or go to a pet store and go into the fish tank section to get check valves, either ones will work, also look through the forum, someone has posted several pics..

here is a homo one I have..

https://www.homemadeturbo.com/misc/cv_diagram.jpg

Re:check valves? what kind?
 

While Im posting old pics today.....heres another:

http://a0.cpimg.com/image/5C/EA/9371...-028001E0-.jpg

Automotive store, Pet store, junkyard (free).

Re:check valves? what kind?
 

Sorry, but what are these check valves used for?
And why/where do people mount them???
I'm lost... :-\

Re:check valves? what kind?
 

check vlaves are just so the map sensor does not see any boost so it wont throw up a CEL.Many people use this instead of a missing link to save money at teh cost of apperance. Look at Jeff's paint drawing.

Re:check valves? what kind?
 

heh...buy my missing link instead =P

Re:check valves? what kind?
 

ill go the check valve rout

Re:check valves? what kind?
 

what about pics for a 94' civic 1.6 sohc vtec, not seeing how the pics are going to work for me, asking for pics thanks

Re:check valves? what kind?
 

they work the same for all, do you know where your map sensor is? do you know where your tb is? if so, then you should unerstand, if not, go buy a hemls manual for your car.

Re:check valves? what kind?
 

that is for a old rex on the pics, and my map sensor mount to the throttle body

Re:check valves? what kind?
 

it's the same procedure, just your map sensor is in a different location

Re:check valves? what kind?
 

then how does the vaccum line fit to the bottom of the map sensor

Re:check valves? what kind?
 

ohh, that's the fun part ;D you have to take one of the t fittings and shove the end in the hole where your map sensor was (assuming that you took it off) just run the vaccum line off of that (and a check vavle) and then just add like one or two more t's with check valves in the line. your map sensor isn't going to fit where it was so you can just zip tie it somwhere (or leave it hanging if you want). is that what you needed??

Re:check valves? what kind?
 

YES, so ram a t fitting into the throttle body and the map sensor

Re:check valves? what kind?
 

A nicer way would be to get a fitting that actually fits in the hole where the MAP sensor was and JB weld it there. Then, you can run a hose off the fitting and insert T's and check valves, (and a boost gauge fitting, and a BOV fitting), and then end it with your MAP sensor.

Re:check valves? what kind?
 

Missing link works nicely. Sometimes you find check valve set-ups on ebay. I tried a set, but 8 psi was too much for them (2 valves). I don't like the idea of using JB weld at the original sensor location, you may want to return to the stock set-up someday. Also note that the communicating hole to the manifold is in the side of the bore for the MAP sensor (or at least mine was). You must not cover the communicating hole when installing your fitting (like I did the first time). Also note that if you would like to have all available boost, this method looses a small amount (probably insignificant). If you use check valves, make sure you test the valves to make sure they bleed pressure off going to the sensor, and also close off for vacume to the sensor. Also make sure you have tight connections, you don't want to blow a line off under boost.

Just a thought...who says you must use the original MAP sensor port. I think it communicates directly with the manifold plenum chamber. If so, perhaps you may want to plug the original location and simply tee into another vacume line which communicates directly with the plenum chamber. This will eliminate the effort to get your fitting to stick into the shallow MAP sensor port. Try using a reducing tee and/or an orfice to restrict the flow toward the check valves and MAP sensor. Anybody have any thoughts on this.

Another thought... who says that you must bleed off the pressure before it gets to the MAP sensor. Why not place a check valve in line to the MAP and tee in between a second check valve to bleed any presure which gets by the first check valve. Close examination of the missing link appears to do this except they use a restrictive filter for the second check valve. Check the text schematic below.

(Manifold)--->l--T--(MAP sensor)
l
L--l<--(atmospheric pressure)

Where >l or l< are the check valves showing direction checked and the T is a tee, all others are lines (vacume tubing). Hopefully my post retains the proper format.

Happy boosting,
Sam

Re:check valves? what kind?
 

About the O2 sensor, on my 92' Civic EX I used the same sensor in an HF manifold. I am under the impression bolt up locations and gaskets are the same for HF and VX Manifolds. I would expect the O2 sensore to be the same also.

Happy boosting,
Sam

Re:check valves? what kind?
 

I tried the method of placing the check valve inline with the extra check valve to vent pressure just in case, but that configuration didn't work. Any small rev in idle would cause the car to stall. I can't figure out any reason for why that would happen but I gave up on the idea.

Also, about my earlier suggestion, I forgot that the check valves would prevent the boost gauge and fmu from getting any boost. Silly me.

Re:check valves? what kind?
 

Couldnt you just disconnect the line that goes from the TB to the MAP? maybe put a filter on each end so you dont get anything into them?

Re:check valves? what kind?
 

BTW...I hooked my boost gage to another direct vacume line when I was trying the valves. I t'd into the vacume line going to the fuel regulator for it and the bov.

No..you cannot totally bypass the MAP with the stock sytem. It is part of the Electronics which controls your injectors (fuel).

Happy boosting...
Sam

Re: check valves? what kind?
 

im using a old safc that can only remove 30% of fuel from my 450cc (i know im still running uber rich ) But .. when i hit 10 psi my map sensor see boost , do you think adding 1 or 2 check valves using a afc setup would work ?

Uberdata and Wideband kit is on its way alrdy. sould have it in 2 weeks or so it's only to see if i can fix these problem before switching management ...