So I’ve been only able to make 6-7 psi only and I have downpipe midpipe cat back and airfilter kit.

on stock turbos with no boost controller. But I would think it should be making more boost than that? I’ve tried to check for boost leaks etc but I came across this vacuum line that seems to be connected/shared to turbo (i) wastegate control and (j) turbo pre control solenoids vacuum?
It looks like there is a pretty old vacuum cap on it. Is this correct???

im thinking this might be a culprit for the low boost issue?

 

It looks like it's the empty, unused pipe. I've got a cap in the same place. It's labelled on the colour vaccum diagram on the left of the Charge Relief valve (H).

 

hmmm really? There is the empty pipe that connects to nothing open on both ends. You can see it in the top pic. Right above the pointed finger.. is that the one you’re talking about?

 

It's hard to tell from the picture, but if you trace the the capped hardline, it should be an "L" shaped pipe (from the cap it goes down, then bends towards the Center of the engine to the right and ends open horizontal)

At first I thought the cap was the pressure line for the oil injectors, but that should be the line behind it (series of 3 lines in a "tube" like chamber where the Wastegate and Precontrol solenoids connect)

I'm suspicious of that open one, I didn't see that originally. I'll check if I can see what line it is.

 

Ok, sorry mate, I was incorrect.

The open one you pointed out is the empty line, the capped line is meant to be capped. Hard to see on the vaccum diagram (because of the dark blue) but it's there.

(Sorry for potato cam, the glass on my phone camera broke yesterday)



It's in where my finger is pointing between the hardlines



Yep, that's the one, it has a cap on it.

 

That cap is OK.

Did you check for pills in the waste gate lines?

Dale

 

not yet... I don’t know how to but I’ll look it up and check for it. Are you saying there should be a ball or something in the wastegate hard line?
but I’m sure it hasn’t been touched since when I got the car it was completely bone stock...?

 

The pills are just small metal objects with precise holes in them that regulate the rate of air flow to the actuators. If present, you can feel them by gently squeezing the hoses, although the stock twins in 1995 and later cars didn't use pills in the hoses -- instead, they had restrictions built into the nipples that the hoses attach to. The pills and their hoses are located in this drawing (upper right):

 

So looks like I might have thrown out the pills because I just replaced the vacuum lines on those two hoses. I didn’t notice anything in them but now it just those two vacuum silicone hoses... without it does the boost get lower then? That is the culprit to the 6-7 psi limited boost?

 

So sounds like I need to either put the restrictor pills back in those two silicone vacuum hose lines...? Or put TWO manual boost controllers (x2 - one on each of those lines??)
and the vacuum lines doesn’t matter which boost nipple it uses(shares the same source anyway & doesn’t have the restrictor in the nipple 93 r1)?

 

Yes - without the pills, the boost pattern drops to what you are experiencing. Open hoses = low boost. If you can't find OEM replacements, and have a race shop nearby, you might be able to find Holly carburetor jets with the right size openings for the missing pills. Mazda never sold the pills separately -- they came with replacement hoses and the hoses were expensive as a result.

https://www.rx7club.com/3rd-generati...umber-1133173/

 

thanks! So is it better to just get two manual boost controllers then? To adjust and tune the boost to 10-12 psi? Instead of..
sounds like the Holley carb jets work too but might boost higher than 10-12 psi (w some mods I have-do,mp exhaust)?
Or the Holley jets are good maybe get two that are slightly bigger holes than what it came with? 0.064 wastegate (shorter line) and 0.059 (precontrol) longer line?
So I don’t have to adjust and tune the boost controllers?
I have one manual bc.. maybe get one Holley jet for the precontrol let side and put the manual boost controller on the wastegate side??

 

Boost controllers would give you better control if you have any mods that might cause spiking. I'm currently installing a Profec electronic boost controller. I was going to snap a pic of my pills in the hoses but was too slow.

 

One member suggested get the oem pills and then install a boost controller???

if it’s a electronic boost controller do I need just one? Instead if two like the manual??

Since I have one manual boost controller already I’ll probably just get another one for like $25.....

 

Either replace both pills or use a stock pill and 1 manual boost controller - either approach should work, but I have never used manual boost controllers, so I can't offer advice there. Electronic BC would be the preferred solution.

My first mod on my '94 has a Pettit downpipe, and then I added a Racing Beat catback. The mods caused an increase in boost and a nasty boost spike in air temps below 45F, that activated the overboost fuel cut at about 6,000 rpm. I didn't want to clutter up the engine bay with manual boost controllers, so I just removed the stock pill from my wastegate actuator hose and tried a series of larger orifice Holley carb jets until I got the boost spikes under control. The boost pattern is now 11-9 -10, which solved the overboost fuel cut problem and is fine with me. To get closer to 10-8-10 would probably require changing the turbo precontrol actuator hose pill to a different orifice size. In hindsight, it might have been easier to go with manual boost controllers. I never pinned down exactly what the stock pill orifices were, or whether the 2 pills are the same size. There was conflicting info about their sizes on the internet, and I had no way to measure my pills.

 

I'm setting mine up to replace both pills, but I have seen some that just replace one. I'd probably just get a second manual, since they're cheap, you're half there, and you don't have your pills currently. I went electronic because I wanted something that had the ability to compensate a bit more for ambient conditions, like Resterof mentioned in sub-45 deg temps. The manual boost controller has the same functionality as a pill, in that it restricts air flow. The manual unit is adjustable though, where as the stock pill is a fixed orifice. If you decided later you wanted an electronic, it would be super easy to swap out the manuals to it.

 

Retserof- thanks for your experience and feedback. I believe they are two slightly different sizes with the wastegate hole being bigger? (0.064 inch vs 0.059?)

yeah I guess it could be a bit of a hassle to swap out different sized jets to adjust the boost just right.. do the Holley jets fit right in the vacuum lines though? They are that small?

so leaving the stock pill on the precontrol side and changing out only the wastegate side stopped the boost spike/creep? Yes because my car has similar mods (dp/mp/exhaust/air filter)

maybe I can just get two manual boost controllers, adjust it a few times, and leave it alone.. 10 or 11 psi would be great I think? 12 probably pushing it although i do have the apex power fc factory tune

 

The Holley jets I used fit into the OEM 6 mm hoses, with a little bit of lube. However, with the mods you have, you are past the point where electronic boost control makes the most sense. The old rule of thumb was 3 mods or more called for changing from stock pills to custom pills, or manual or electronic boost control.

 

so I accidentally made the right choice by changing out those stock vacuum lines and probably tossing the pills 😅

 

Hey, sometimes you're the bug, sometimes you're the windshield.