Control Boost with ROM Tuning?

CGTuning · Post by **CGTuning** » Wed Oct 24, 2007 3:12 pm

Does anyone know where in the SR20 .bin the boost control table is located?

Trying to run an aftermarket boost solenoid and control boost with the rom.

Matt · Post by **Matt** » Wed Oct 24, 2007 11:56 pm

Only the later model SR ecus (eg S15) have boost control maps in them. Earlier ones dont have them at all

CGTuning · Post by **CGTuning** » Thu Oct 25, 2007 8:09 am

s13s came with a boost solenoid tho. was that not used to control boost?

Matt · Post by **Matt** » Thu Oct 25, 2007 9:03 am

If it was I dont know about a boost map for it. There is a map filled with 0xFF (255) at 8B00 but it doesnt look the same as S14/S15 boost control maps/routine at all

Matt · Post by **Matt** » Thu Oct 25, 2007 10:30 pm

Response from PL S13 boost control solenoid AFAIK is really only an emergency boost cut. For stuff like if the engine overheats etc. I've never seen it being driven with a proper PWM signal

Pingu · Post by **Pingu** » Sun Apr 27, 2008 11:14 am

Only the S14L/S15 SR20DET have boost control thats worth messing with.
The Z32 and others have a system where a solenoid allows vacuum (from just infront of turbo inducer) to evacuate/lower the pressure of the air incident with the turbo wastegate actuator. While this is open the wastegate is very hard to open. When the boost hits a certain level this solenoid turns off - and the only path to the actuator is from the pressurised pipework - giving normal regulation. Controlling these solenoids with a variable duty signal is effective but quite tricky!

On the U12/S13 CA18 - the boost solenoid is for controlling ramp rather than for maintaining a different peak level than the actuator/whole system is designed for. I think this is also the case with the S13 SR20DET. IMO the best thing to do here is to employ another method of boost control.

Ferret · Post by **Ferret** » Sun Apr 27, 2008 9:10 pm

I assumed that the "High boost duty" and "Knock boost duty" maps control the boost solenoid duty cycle, I guess I was wrong.

What do they control?

Avner.

Matt · Post by **Matt** » Sun Apr 27, 2008 10:42 pm

For the S14A/S15 those ECUs have those two maps which apparently control the duty cycle

Now we are just starting to get the Type 4 boards going, are going to be playing with those tables more to find out more about them

Which ECU were you looking at with those tables?

Ferret · Post by **Ferret** » Sun Apr 27, 2008 11:52 pm

I just opend at a few random S14 SR20DET bins I downloaded from your site and they all seem to have them.

Can the sofware show tables that are not supported by the ECU?

I'm playing around with the software(I mean "learning" it), while I am waiting to get a board with a 75F00 bin from Pete for my 1995 Euro S14.

chris2712au · Post by **chris2712au** » Fri Jun 20, 2008 12:20 pm

I would love to bin my boost tee if i could control the boost well on my s15... has anyone done it and is it possible with nistune..

Matt · Post by **Matt** » Fri Jun 20, 2008 12:40 pm

We havent played with it yet on S15 but it should be possible to modify those boost maps.

BNR32 also has a boost map but no scales for that map (hence no trace so you would have to look at the fuel map trace to get a rough idea where its at)

When your board arrives let us know how you go with it. I can hook up the boost solenoid output to the scope and have a look at how its affected. The maps display this as a duty cycle of how the PWM signal works so it should match that

PL · Post by PL » Sun Jun 22, 2008 11:43 am

Hey guys,

I've played around a bit with the boost control maps on S14/S15. I did some experimenting on the bench and the boost control solenoid was certainly being affected when the high/low boost duty maps were adjusted. I monitored the PWM signal using a CRO and I could see the signal changing. So it SHOULD work!

It appears to not only be mapped to load/RPM but also to throttle position. Which should make it a very good system.

Unfortunately I've been continually frustrated by cars which have had the factory boost control solenoid removed. So I haven't been able to dyno test the system yet.

I did have a small play with it on a stock S15 on the dyno but could not get it to respond. Which was most disappointing.

I really wanna get this working cos it should be a great system. I'd be very interested in any results other people obtain. FWIW the valve is run as a simple "bleed" and relies on the usual Nissan system of brass jets to obtain the correct boost level. So you need the jets and stuff in the hoses for it to work.

Research continues....

PL

Pingu · Post by **Pingu** » Sun Jun 22, 2008 12:01 pm

Have had breif opportunities to play with it also on the S14/S15 DET.
It works quite well - not only in controlling part throttle output but in affecting boost pressures above the natural regulated pressure of the wastegate actuator.

A map sensor input into nistune, and a boost auto tuner similar to the AFR autotuner would be great in tuning systems where the internal wastegate is under greater influence from free intake and exhaust's - wally boost spikes etc.. - I do imagine it would be very effective.

I may try this next week on my ca18det if i can locate a boost solenoid from an S15/S14. (S14 DET ecu wired in).

PL · Post by PL » Sun Jun 22, 2008 1:11 pm

Sounds very encouraging. I'd be happy if I could just map boost across RPM. Just stuff like being able to remove boost spikes and being able to run more boost at high RPM than in the midrange would be great.

Can't wait to get into it. Still don't know why that S15 didn't respond...

PL

chris2712au · Post by **chris2712au** » Sun Jun 22, 2008 4:37 pm

hey pete,

what could be of interest to you is that on my s15 I had those restrictors in one in the actuator line and one in the boost signal line from the manifold(standard)... i replaced the solenoid with only a bleed valve ( no ball gated tee peice just the standard nissan tee) and left the restrictors in.... what i found was with the bleed valve full open as in full bleed no boost above 11 psi... with no restrictors in the bleed valve still couldnt bleed enough air(still no boost above 11)....

when i put in the spring ball gated tee everything was ok... cause more restriction to boost signal...

you need a smaller restrictor on the signal line from the manifold or buy a needle valve inline to limit the amount of air going to the standard solenoind... then crank the solenoid to 100%PWM then set the inline restrictor to the max boost level you want... then glue it...

then you should be able to make a goer of it... although it will effect the minimum boost level... it is just a different philosophy restrict rather than bleed...