I found these while poking about, I wrongly identified them as prvr solenoids from this picture, because that's basically where they can be found.

 

 

Here is one of mine

 

 

They are a 2 stage factory fitted electronic boost controller. We all know the det sensor can initiate safety boost, sometimes it dies and the ecu worries and also enters safety boost. It is the boost solenoids that alow the car to do that. They must just be a 2 position restrictor inside the cylinder that sit between the pressure source and the wastegate (just like any boost control) to set either normal 9psi or safety 7psi.

 

I found my passenger side one had a snapped off vac line (a possible boost leak but I don't know) which prompted this digging.

 

Upon inspection I found this

 

 

I sent these pictures to a mate hence the daft annotations.

 

So what I decided to do was to chin them off, as they are a potential point of failure, my det sensor is already dead, I don't want them. But I didn't want to panic my ecu so I left them in, blocked the feed from the turbo intake and looped the two ports.

 

If I am right this is a sucsessful bypass. PLEASE COMMENT IF ANY OF THIS IS WRONG. I am not too proud :)

 

Pretty sure you can just run a single line to the Wastegate actuator, don't forget the restrictor, that's the thicker tube. The two 3mm ID ones are simply a loop to allow the solenoid to forfil it's function. Not sure about unplugging them. I'm going to bin mine off over winter, who needs the bloody things.

You will find it fiddly to replace the actuator line in situee, esp on the drivers side.

I already have a HKSEVC5 boost controller so they weren't doing anything, other than the way that one had been left, I think was a boost leak.

 

My EBC sits near the battery, takes a reading from the ballance bar, then runs a vac/boost line outwards that goes down to the passenger turbo, then underneath the engine and up into the bottom of the driver turbo actuator.

 

Glad I didn't fit it! But if I had, I wouldnt have left a bloody open vac line on the passenger boost solenoid.

Iff the solenoids are in the bin Tom then not only will you lose the dett sensor but also the reduced boost on a stone cold motor feature...Ok for true petrol heads who dont cane there cars on a cold motor;)

I didn't know it had that feature till I read up on it today, and I am glad to say that's because I have never set it off :)

 

I don't just wait for the water gauge to hit the middle! I have a full on warm up procedure mate :lol:

 

I went crackers at my cousin once for going gentle 1st, 2nd, 3rd, then f$@#ing WOT in 4th. He was rebriefed shall we say.

I didn't know it had that feature till I read up on it today, and I am glad to say that's because I have never set it off :)

 

I don't just wait for the water gauge to hit the middle! I have a full on warm up procedure mate :lol:

 

I went crackers at my cousin once for going gentle 1st, 2nd, 3rd, then f$@#ing WOT in 4th. He was rebriefed shall we say.

 

Or Re-educated via impacting flesh..

You don't lose the (useless) knock sensor functionality if the solenoids are removed, it will still drop onto the safety maps.

So what I have done, leaving them plugged in but not plumbed in should be ok? It shouldn't throw a code or put it in safety map?

Yeah, I'd like to know too. Can they simply be unplugged and bypassed, then the knock sensor bypassed with a resistor?

You don't lose the (useless) knock sensor functionality if the solenoids are removed, it will still drop onto the safety maps.

 

How can the ECU reduce boost...

Only using the solenoids, but noz has said ot can change the mapping to a safety map. Regardless of boost the timing and whatever else it can control will be restricted.

The solenoid just opens a different path to the waste gate to show unrestricted true pressure on to the Wastegate so it opens at 7psi, stock there is a tiny brass restrictor in line that acts like a boost jet tricking the car to produce 9psi. When knock is seen, ie code 34 it activates the solenoid to lower the boost to 7psi and retards timing. That's how I understand it anyway.

All true Stephen, but what Noz said as I understand it is

 

The knock sensor can drop boost to 7psi

 

The knock sensor can also trigger a different map on the ECU

 

Or rather does both at the same time, but if you remove the solenoid it (the det sensor) will just change the map.

Ok.

 

If the knock sensor detects knock (spuriously or not), in the load cells where knock monitoring is active, the ECU uses the knock maps and if solenoids are fitted boost is reduced (safety boost = actuator pressure).

 

Knock detection does NOT trigger a code 34. Code 34 is solely for a faulty knock sensor or issue with the asociated wiring.

 

With code 34 in place, system is in failsafe mode: Knock maps & safety boost (where applicable).

 

If there are no boost solenoids, and knock is detected (spuriously or not), the ECU uses the knock maps but has no ability to reduce the boost.

 

The knock sensor is redundant once the car is no longer standard and a specific grade of fuel is specified.

 

The knock sensor is there for protecting against user error, i.e. wrong grade of fuel used.

 

Unintentional overboost scenario is supposed to be protected by a fuel cut. All VG30DETT have a fuel cut programmed, but it is set at an arbitrary load value of 150. This equates to roughly 28psi and a theoretical 500bhp on the stock injectors & single MAF, which is physically impossible at standard fuel pressure. This is just one programming/mapping mistake that all standard ECUs have. Every other standard Nissan ECU (generally-speaking) has an overboost fuel-cut at a usable level. See other Nissan model-specific forums for further info.

 

Some Nissan ECUs have identical low octane (knock) maps & high octane (regular/main) maps.

 

:)

Edited October 25, 201411 yr by Noz

Thanks for clarifying Noel. My plan was/is to unplug and simply bypass the small tubes on the boost solenoid. Basically run the 6mm tube straight to the actuator, as il be using an aftermarket MBC. That's fine is it? No special measures required? I also plan to remove the stock knock sensor because it's as you have pointed out before, not as useful as it could be. This will be replaced with an aftermarket knock sensor one what works across the range, or am I confusing myself and thinking about a wide band AFR gauge? You can't just unplug the knock sensor either though can you as it would throw 34 so a restor is required to make it believe it still has the circuit?

I fully understood the funtion of the noids i was being sarcastic to Noel:rofl::rofl:...But he always seems to post more interesting info which over-rides anything else:tt2:. Keep it up Nozzler:thumbup1:

Thanks for clarifying Noel. My plan was/is to unplug and simply bypass the small tubes on the boost solenoid. Basically run the 6mm tube straight to the actuator, as il be using an aftermarket MBC. That's fine is it? No special measures required? I also plan to remove the stock knock sensor because it's as you have pointed out before, not as useful as it could be. This will be replaced with an aftermarket knock sensor one what works across the range, or am I confusing myself and thinking about a wide band AFR gauge? You can't just unplug the knock sensor either though can you as it would throw 34 so a restor is required to make it believe it still has the circuit?

 

It's fine to completely remove the solenoids and run the actuator lines directly to a tee which will then go to the output of the MBC. The Zed was a technical masterpiece (AIVs, PRVR, boost solenoids etc etc), a supercar for the masses I guess. But there are a lot of items that are simply not needed. Boost solenoids being one of them. Yes, they keep boost levels down whilst the car is warming up, but anyone with half a brain can do that. Just don't drive it hard :laugh:

 

Aftermarket sensors can be programmed to bypass unwanted frequencies to ensure accuracy of output (they're just bandpass circuits at the end of the day. For info, the knock frequency for a VG30DETT with stock pistons is 6.62kHz (900/πr) ). When I worked with a high-comp SR20DE-T, at low RPM, high load I could induce very mild detonation that my aftermarket knock sensor completely failed to pick up. It was clear as day in my headphones that I had clamped to the knock sensor itself. I'd say that knock monitoring is essential for hard track work where elevated intake temps can induce detonation. Anything running high boost pressure as well, in case something begins to go awry and you need to come off the gas immediately. You don't typically need a knock sensor to work throught the rev range, detonation is more an issue at peak torque than higher up, which is going to be masked by increasingly loud valve train noise.

 

I look after a high-powered Z32 (613bhp, maxing out the single stock MAF over 5v) and that runs an aftermarket knock sensor. When I map the car, there is a constant code 34 so I actually tune the knock maps rather than the standard ones. He isn't bothered about fitting a 1M ohm resistor, which is fair enough as it makes zero difference, so it's entirely up to you and the mapping on your ECU.

 

As a slight aside, on my own car I used to get away with just disabling the knock flag, so the ECU simply ignores DTC code 34. Since running a different firmware in my Nistune ECU, it was working from the knock maps until I fitted a 1M ohm resistor. I now carry a bag of 1M ohm resistors as part of my mapping toolkit.