1988 mazda rx7 n/a vacuum lines
 

I just bought this car and the idle has been rough, I changed the spark plugs because I noticed one was cracked I put 4 nbk bur7eq (but now I know you need to have 2 leading and 2 trailing (bur9eq). If I turn the ac one the idle gets real low and will sometimes die, so I was able to manage now it dies when I stop or take corners with the ac on. I put some ngk spark plug wires on it and still is rough. I took some pictures of lines im not sure where they go.

Attachment 660404

the picture above, the hose goes to the container in the picture below

Attachment 660405

Attachment 660406
if im not mistaken this hose comes from the pressure sensor.

I also have a video of the idling incase any of yall are that great with cars to hear the problem.


I have also used search threads. I got on rotaryheads.com but I cant see to figure out where it goes. if you could perhaps take detailed pictures of the lines and label them or maybe make a video so for people in the future that would be great!

First hose is not important as it runs to the reservoir which would inject coolant into the manifold on cold starts but the system is not effective thus it is not used. The Pressure Sensor has but one hose so if there currently isn't a hose connected to it then probably the hose in the second pic belongs to that sensor.

sorry I didn't clarify that picture. the hose with sensor in the pic is the hose that comes off the sensor.

There is a component bolted to the passenger side of the engine called the ACV. It appears to have a flat hat or cap on top of it a couple of inches across. Just to the right of the hat is a port pointing towards the passenger fender and this is where the Pressure Sensor hose connects to.

looks like the pressure sensor port has a line attached to it with a tee on it. what the PO has it leading to i don't know but it's pointing to the throttle body now.

gotta love all these mickey mouse hack jobs.

As Rotary Evolution pointed out is appears you have a hose connected to the Pressure Sensor port already which has a T in it and it also appears that one of the hoses is connected to the port on top of the UIM which points directly upward at the hood. This port is supposed to be capped. This port is directly behind the part of the ACV which looks like a hat.

the vacuum diagram is rather simple to follow and should eliminate many further questions.

https://www.rx7club.com/attachments/...est-s4-vac-jpg

the only one that isn't well marked is the pressure sensor port, which is to the right of the hat solenoid that satch mentioned in the top picture. both nipples under the secondary fuel rail should be capped and aren't shown as used ports in the picture.

I think I got it. sorry I noticed the video was private. I just want the car running good and the idle to be great

update on what I did. I reread what you guys said and I showed you what I thought was correct

get a vacuum cap, remove that line that someone installed and put the cap on the port underneath the plastic throttle body elbow(the one facing straight up).

run the pressure sensor hose to the bottom open port you are left with(the one facing the passenger side of the car).

and you can ditch the whole sub zero system in the second picture, it's a waste of space and weight. throw it in the garbage, no one will want it.

And the hose to the Pressure Sensor has a restrictor pill inside it and it's usually located a few inches from the sensor connection.

Heck yeah!!
 

I have really been needing this same question answered and the diagram above is perfect...now only if i could figure out how to get my 88 gtu n/a down to as few vacuum lines as possible!! i have no idea what to cap and what not to....