boost control using nistune experiences anyone ?

[chris2712au]

Nissan solenoid = 32 ohms
MAC valve = 27 ohms

So it'd probably work. Whack a diode (1N4004 or similar) across it to help protect the driver. Cathode (stripe) towards the 12V end.

PL

youve already done it..

chris

[Fordy]

tested the nissan valve and the mac solenoid i've got

nissan is 30ohms
mac is 26ohms

anybody know if it will blow a ecu driver if its connected without a diode across the valve?

[PL]

Thanks Chris. Happy for you to be my "external memory".

OK, so if the coil resistance is similar then it should be OK. Given that these things are pulsed on-off continuously I reckon it'd be good to have a diode across it. This will snub out the nasty spikes that happen when coils are turned off.

That 1N4004 I mentioned previously is a very common diode and can be had at any electronics parts retailer for a few cents. Any of the 1N400x series will be fine.

PL

[chris2712au]

from what I can read is that nissan like to leave in redundant code in their programming.. maybe the boost map is 3d if fitted with X option.. or did they retain the function of the s14 that has the map sensor but simply not use it ? thats if the s14 boost sensor is not for boost cut only.. well i think it was the s14..

yeah it was on pin 35... would be interesting to do a trace and see what its function was in the ECU..

[chris2712au]

I was asked if it could be used for a intercooler spray control.. yes it can but beware that the stock solenoid does not flow water well and the spring will rust.. and alternative is to mount the wanter tank low and send air to it then the water gets pushed out in a upwards direction to the nozzles.. upside is the nozzles dont drip and the solenoid never sees water..

You can also put in series a boost switch.. but the sprays should be on believe it or not off boost so the intercooler is cold ready to absorb the heat not already hot trying to cool it down.. in principle it does work but with this system I am not covinced it will have low water consumption and be effective..

[Fordy]

could you not use the boost solenoid feed to activate a relay for a intercooler spray kit?

[Adrian]

What happens to this?
tried to map the standart solenoid today to 1,2bar on a s14 with s14a ecu 75f05. Also tried alot with different restriction pills, but it seems not possible to get a accurate boostcontroll with motlre than 0,1bar controll range.
I use MAC valves for Evo's, Subaru's and on standalone Ecu's with grate sucsess.

Have someone now tried it and how good does it work? On the MAC valves it doesn't matter how you connect the terminals. That meas there is now diode. Can I just connect it or could i damage the driver? If something goes wrong, would i only damage the output driver of the boost control solenoid or maybee the hole ecu?

[Matt]

I'm going to post PLs email about this here which was sent to Adrian over the weekend since it contains useful info. We found about a 14psi maximum with standard jet sizes on my S14A

Hey guys,

If using the factory solenoid you need to be aware that they operate as a variable air bleed - which depends on the size of the brass jets that Nissan fit in the hoses to set the boost window. Standard jets will allow the solenoid to adjust boost around the factory boost setting of 10 psi or so. I think I got to about 14psi on an S15 with standard jets. You can adjust the jet sizes to change the window that the solenoid will work in. I did a friend's S15 once and we successfully adjusted the jets to achieve a boost window around 18psi. The solenoid was then mapped to adjust boost around that level.

Unfortunately adjusting the jet sizes is a bit fiddly and many people opt for the easy option of binning the solenoid and just fitting a bleed/EBC.

Please see attached diagrams taken from S14/15 FSM's with my mods in red. Increasing the size of "Orifice 2" will allow the solenoid to bleed off more air = increase boost. Small increases make a big difference, so get a set of number drills (example only) and go for it. No, I don't remember the exact sizes. It'll vary from car to car anyway depending on what turbo/actuator is fitted. I got two sets of drills - one does 0.3 to 1.6mm and the other does 1.0 to 2.0mm. That should cover it.

I'm going to be trying out a Mac valve next with the Nissan ECU on my S14A and see how that works also compared to the factory solenoid. From what Pete has written the factory works fine if you take the time to get the jet sizes right (which can be fiddly)

[Matt]

I've put together a document, and hosted Chris's document:
http://nistune.com/docs/Chris%20Boost%2 ... istune.pdf
http://nistune.com/docs/Nistune%20Boost%20Control.pdf

Update required to 1.2.12 test version to fix the RPM scale (just found this today, as changing R34 tables affected this scale)