Vacuum hose diagram
 

I am following the vacuum hose diagram I found on rx7club so I can replace all the hoses for my engine. I think I've got everything sorted except with solenoid A the diagram is a bit hard to follow. I've attached a screen shot of the hose I am having trouble with, it's the light blue one. From the diagram it looks like there should be a nipple between the light brown hose and the redish coloured hose. But I can't find anything there. Is it just the way the diagram is drawn and it is actually more around the back of the manifold, near the firewall that it attaches? I can find nipple there that is not otherwise mentioned in the diagram so I presume that is it. Can anyone confirm?

http://www.turborx7.com/images/Techn...e_diagram2.jpg

Hose ot Pressure Regulator
 

Have you anything attached to the pressure regulator yet? I.e. where your arrow points. That is toward the back.

Nope, nothing there yet, which is why I am guessing solenoid A connects to it. The diagram shows the blue hose connecting around the front of the inlet manifold (front being from the diagrams pov), but I'm guessing it is more around the right hand side (near the firewall)

Is your pressure regulator there, or has it been deleted? Send a pic.

Solenoid A connects to Pressure Regulator
 

The attached show the post and pre 1995 December vacuum diagrams.


Attachment 590798

The pressure regulator is at the end of the fuel rail and so somewhat around the back as you suggest. The should be a tube sticking up from it.

It is interesting to know that the pressure regulator will turn on if the vacuum is off. And off when the vacuum is on. Therefore, you want to make sure that the vacuum is being consistently applied. I believe the pressure regulator only needs to be turned on in very specific circumstances (hot or cold start, I can't recall) so if it is otherwise on your fuel pressure may be too high.


This is my understanding from somewhat vague manual descriptions. I invite more knowledgeable persons to correct me.

See attachment. I presume that black hose goes to solenoid A?

If the diagram is to be believed. Not sure how you'd test to confirm its working.

Be careful not to disturb that furl line.


Also sometimes the PRC fails. Not sure how you check while it is still on engine. Are you replacing the solenoids? If they are 20 years old, might be a good idea. The solenoid itself could fail, or the electric connector malfunction. Was the engine running. If so, did you test for codes?

There's a nipple on the LIM, that goes to the back of solenoid A, then the other side of solenoid A goes to the FPR which is mounted on the end of the secondary rail.

It's all quite simple, really...........




Attachment 590844

These may or may not be two of the connection points. Its not wonderfully explicit.


Attachment 590846

Attachment 590847

Here is what the PRC is for and how to check it.


Attachment 590853

Attachment 590854

Engine was running but not perfectly. It would sometimes drop boost momentarily when the second turbo came online. Not sure about codes, I haven't checked for a while. I tested all the solenoids following this guide https://www.rx7club.com/3rd-generati...-stuff-802060/ . I managed to get them mostly good using 2 rats nests. Some had leaks but were fairly slow leaks. One of the Wastegate and Precontrol Solenoids had a pretty bad leak under pressure but not vacuum. If it is still not running right I'll switch those out. The good thing with those is they aren't too hard to get to.

im guessing you got it figured out but the hose youre talking about goes from the nipple in the bottom center of the lim to the solenoid and from the solenoid to the fpr on the secondary rail. theres is a nipple on the bottom of it.

Attachment 605884

https://cimg4.ibsrv.net/gimg/www.rx7...3280f04cb6.png

Hesitation between turbos.
 

My understanding is managing the hesitation when transitioning to the second turbo has proven very difficult to remedy. It is mentioned even in the very first write-ups in the likes of Road and Track. I went from Parrallel to Sequential and back to Parallel within a year. The sequential was very nice, but we were still chasing the hesitation, when I popped a few seals and had to rebuild.

I'd suggest you go for all new solenoids if you can. Replacing a 20 year old solenoid with a 20 year old solenoid invites grief. Word is there is a fairly high failure rate even for NOS solenoids. (New Old Stock)

Who sells or where can one buy new solenoids from? Is there an aftermarket company selling these or is it a Mazda only item?

Source for Solenoids
 

Well up here we can go to any Mazda Canada dealer. Single solenoids are about C$100 and the dual duty (green one) about $200, as I recall. Atkins Rotary in Washington State has extensive NOS parts and likely most of the solenoids. They cost about the same on line after exchange and mailing. There are English language parts suppliers in Japan on line as well, and again the price works out about the same. Delivery to the Westcoast takes about a week.


I believe 96 and newer got the rat box rather than the rats nest. It has about 7 solenoids and three check valves in a single unit. Cost about $550 Cdn on line. I have not heard of anyone using to replace the rats nest. I included above the routing diagram for the rat box compared to the rat's nest.

Rat Box in Place
 

https://cimg1.ibsrv.net/gimg/www.rx7...7b08164a9d.jpg


Fortunately, whomever did the
paralleling of my turbo left the 99 harness in place. So when we dropped the rat box in everything clicked in by colour code in a matter of seconds. This was all pulled when we went back to Parrallel.

Rat Box Diagrams
 

Attachment 590926

Attachment 590927

Check Valves
 

You might want to replace the old check valves as well. Dale Clark on here sometimes brings them in in bulk.


Looks like you may need one coming off the UIM (part 13-995).


Attachment 590933

Attachment 590934


You may want to replace the waterhose that comes off the throttle body and runs to block behind the PRC. (13-881A) Pain to replace when it splits.