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Only boosting to 7 psi

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Old Mar 25, 2020 | 11:43 PM
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Only boosting to 7 psi

Hi all

The issue I've been having is the boost pattern is 7-5-7 instead of the typical 10-8-10. I also notice a distinctive lack of power too. I've seen a similar thread detailing the same issue I'm having, and the possible solutions being missing pills in the pre control and wastegate vacuum hoses, or that the precontrol and wastegate solenoid electrical connectors are crossed, however I'm having trouble with locating these as I'm new to the rotary engine. I've had a look at the vacuum line diagrams but still have been unable to make sense of any of it.

The previous owner said it was a sticky 2nd turbo actuator, however from my own research this doesn't seem to be correct.

I've attached 4 images, the first 2 being of what I believe is a solenoid that looks to have had the wire almost frayed through (which i'm wondering if it's one of the trouble solenoids in question), and the 3rd being of what I think are the 2 hoses, but even after consulting the vacuum diagram am still unsure.

Any help would be greatly appreciated.

Thanks
Michael


Zoomed out view for context in engine bay

Frayed solenoid

Pre control and Wastegate vacuum hoses?
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Old Mar 26, 2020 | 12:14 AM
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Update: I've found the pre control and waste gate solenoids and looks like they're on the correct way. Now I'm just guessing that the pills are missing in the hoses. I've yet to find out where I can find these hoses and where the pills would be located inside them. Would they be up towards the solenoids or down towards the actuators? Thanks.
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Old Mar 26, 2020 | 01:32 AM
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This should help.
https://www.rx7club.com/3rd-generati...-turbo-749702/

The restrictor pills are on the wastegate and pre-control actuators in front of the turbo assembly (see above thread for better views). I believe your third picture shows them. Pinch the line. You should be able to feel it get harder where the restrictor pill is in them.

That first "solenoid" is your stock O2 sensor, btw.

Last edited by JSpek92; Mar 26, 2020 at 01:34 AM.
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Old Mar 26, 2020 | 12:39 PM
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Any relevant mods to the car? Are you still on stock ECU?
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Old Mar 26, 2020 | 12:42 PM
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If you are getting 7-5-7 the general turbo control is working like it should be. You'd have a big lack of secondary boost if the control system was at fault.

Either missing pills (which I doubt, those look like stock hoses), you have a decent sized boost leak (which is quite possible) or you have a badly cracked turbine housing around the wastegate.

+1 on what mods are on the car. I can see you have the 96+ Y-pipe on the car so that eliminates one major source for a boost leak.

Dale
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Old Mar 26, 2020 | 12:53 PM
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I'm with Dale. The fact that there's still a boost "crossover" as the second turbo comes online tells us that the turbo actuators are working.
I'd look for boost leaks. The fact that 7psi is your max across the RPM band seems like you have a leak that simply doesn't hold any more than that.
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Old Mar 26, 2020 | 12:56 PM
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Engine was rebuilt by a reputable shop about 7000km ago. Adrenalinr full exhaust, stock ECU and that's about it really. Everything else is stock. Has 95k kms on the clock.
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Old Mar 26, 2020 | 01:02 PM
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The rubber connector from the y-pipe to the crossover is generally a prime suspect for boost leaks in stock original cars

On the control side, the solenoids and actuators get sticky over time. They should all be tested (hot and cold)
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Old Mar 26, 2020 | 01:02 PM
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Originally Posted by Myaanz
Engine was rebuilt by a reputable shop about 7000km ago. Adrenalinr full exhaust, stock ECU and that's about it really. Everything else is stock. Has 95k kms on the clock.
What's the diameter of the exhaust? Do you have either of the OEM catalytic converters installed currently?

Also, do poke around for potential boost leaks. May want to check the condition of the intercooler too.
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Old Mar 26, 2020 | 01:25 PM
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Just took off both the pre control and waste gate hoses as shown in 3rd photo, and no pills in either of them. Exhaust is 3inch and has what looks to be stock cat towards the engine side of the exhaust.
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Old Mar 26, 2020 | 01:28 PM
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Originally Posted by TomU
The rubber connector from the y-pipe to the crossover is generally a prime suspect for boost leaks in stock original cars

On the control side, the solenoids and actuators get sticky over time. They should all be tested (hot and cold)
Excuse my ignorance, but the y pipe is the section of piping the goes to the top of the turbos correct? Where could I locate this rubber connector?
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Old Mar 26, 2020 | 01:31 PM
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Intercooler also seems to be fine too. Lil rust dust around the bottom, but there's no damage to any of the fins.
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Old Mar 26, 2020 | 02:21 PM
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Originally Posted by Myaanz
Excuse my ignorance, but the y pipe is the section of piping the goes to the top of the turbos correct? Where could I locate this rubber connector?
The y-pipe goes to the IC, from the turbos, and yes it's on top of the turbos. Connector is shown below

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Old Mar 26, 2020 | 02:36 PM
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Your car doesn't have that rubber connector. You have the later 96+ Y-pipe that bolts together instead of having a rubber coupler.

You may not have the pills in there since you have a stock ECU and a fairly open exhaust. With the pills you'd probably be running too much boost on the stock ECU. They may have removed them on purpose.

Dale
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Old Mar 26, 2020 | 02:48 PM
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Originally Posted by DaleClark
Your car doesn't have that rubber connector. You have the later 96+ Y-pipe that bolts together instead of having a rubber coupler.

You may not have the pills in there since you have a stock ECU and a fairly open exhaust. With the pills you'd probably be running too much boost on the stock ECU. They may have removed them on purpose.

Dale
In that case, I've got a cheap boost controller that came with the car. Should I try installing that instead? From my understanding it replaces the pills. Is this correct? It looks similar to this one.

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Old Mar 26, 2020 | 03:16 PM
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You can, but I would be VERY careful. Stock ECU you wan to to go to 10psi MAX. Any more than that and you need an aftermarket ECU.

Dale
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Old Mar 26, 2020 | 03:21 PM
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Originally Posted by DaleClark
You can, but I would be VERY careful. Stock ECU you wan to to go to 10psi MAX. Any more than that and you need an aftermarket ECU.

Dale
Ok appreciate the help thanks. If this doesn't solve the issue, just continue to look for boost leaks?
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Old Mar 27, 2020 | 09:16 AM
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Yep. Most likely that's going to be it, you may also want to work with the shop that put everything together and verify their thinking about removing the pills. That sounds logical, though.

Dale
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Old Mar 27, 2020 | 01:26 PM
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Originally Posted by Myaanz
In that case, I've got a cheap boost controller that came with the car. Should I try installing that instead? From my understanding it replaces the pills. Is this correct? It looks similar to this one.
It's commonly called a MBC for manual boost controller. The Hallman ones aren't actually that cheap.

They don't simply replace the pills. You attach them between the compressor nipple and actuator, then block off the second nipple of the actuator. Don't just put a cheap rubber cap on the second nipple - it will rupture and you will overboost.

You will need one MBC for the precontrol. That will adjust your primary boost up to 4500 rpm. A second MBC for wastegate that will control your boost to redline.

I ran dual Hallman MBCs for years. They work, but you do give up some performance. There are nuances to the stock boost control system and solenoid duty cycling that provide better response and more consistency.
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Old Mar 27, 2020 | 05:52 PM
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Originally Posted by alexdimen
It's commonly called a MBC for manual boost controller. The Hallman ones aren't actually that cheap.

They don't simply replace the pills. You attach them between the compressor nipple and actuator, then block off the second nipple of the actuator. Don't just put a cheap rubber cap on the second nipple - it will rupture and you will overboost.

You will need one MBC for the precontrol. That will adjust your primary boost up to 4500 rpm. A second MBC for wastegate that will control your boost to redline.

I ran dual Hallman MBCs for years. They work, but you do give up some performance. There are nuances to the stock boost control system and solenoid duty cycling that provide better response and more consistency.
Taking this into consideration, and also the 4 week lockdown we have here in NZ, would it not be better to find something to act as pills and put them back in the lines to test if they are actually causing the problem?
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Old Mar 30, 2020 | 10:17 AM
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Oh yeah I thought you meant you were going to try MBCs first. Yeah the pills will be a good start.

You can put carb jets in there or make your own. From a couple of sources:

Wastegate (shorter hose TOP) - 0.064in (Drill # 52)
Precontrol (longer hose BOTTOM) - 0.059in (Drill # 53)

Stock Wastegate Pill is about .062"
Stock Turbo Pre-Control is about .058"

There's a lot of talk about playing with pill bores. I would leave that alone personally. I am running stock pills with many mods and two boost settings in PFC. They work fine for me.
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Old Nov 20, 2022 | 04:56 AM
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For any future searchers, heres the part number for the two lines with the pills in them, although you could make them yourself for a lot less.
n3a1-13-zly
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