iain atkins

Hello

Gonna try this instead of my 2-port.

MY97UK standard ECU. I know the restrictor goes in the return line on a 3-port, and i'm 99.9% sure of where the hoses go etc.

I also understand that the smaller the restrictor the lower the boost.

Any other pointers???

Cheers



Iain

john banks

On my MY00 I put the top one to the compressor outlet, side one to the actuator, bottom one back to the inlet. No restrictors.

However, you will need to play with restrictor size (get a valve) to get the control in the right range for your ECU map. The more you restrict the vent hose to the inlet the lower the boost will be since you will be making the actuator diapragm see more of the boost.

With a 3 port the method that works well is to allow it to peak a bit in 5th gear and then it tends to control boost in the lower gears better than a 2 port and can do a proper closed loop setup.

However, I have only fiddled with this with ECU remapping, and use the added benefit of system to judge what gear it is in to boost the maximum duty cycle in lower gears to assist with boost (and breaking gearboxes).

iain atkins

Cheers John

No doubt here goes another half a tank of fuel for testing LOL



Iain

Bob Rawle

On a std car you do normally need to fit the restrictor into the vent pipe ... otherwise the boost can oscillate all over the place.

Be very wary doing it any other way as a sudden rise to high boost levels could result. Varying the size in the vent pipe allows you to tweak levels to suit.

Why are you fitting it ?

iain atkins

Bob,

Just trying to get better control for the time being. I want it to go up and hold 17psi. With the 2-port it's spiky

I know i should get a mappable ecu, but at the moment things are very tight. I do eventually want to 'link'



Iain

john banks

It will only hold 17 PSI if the ECU is programmed (or fooled with an FCD) to hold it.

iain atkins

FCL John.

Will be checking with det cans as well.

It was holding 17 before, but was a little too spiky for my liking

john banks

3 port optimally setup seems to overboost 1.5 PSI in 5th gear if you want to hit target in 2nd gear and up.

iain atkins

John

I was getting overboost by 2 - 2.5psi with the 2-port, so hopefully it will be better.

Thanks for your help John & Bob, much appreciated.

Bob, i will be round the duals in Cirencester, just incase your out and about and feel like giving me a hand

Anyway, i'm off out now.

Once again, thanks for your help

Cheers



Iain

iain atkins

Tried it out today, and it's definately better. . . . . BUT. . .

The solenoid got stuck in the closed (to actuator side) thus actuator seeing no pressure with a 20psi boost cut

If i can guarantee it not to stick then i can see definate advantages, but i'm not willing to risk it until i sort this problem.

I think the valve may be faulty - any ideas on how i can fix it?? Could it just need a blast out with carb cleaner etc , so i'm back to my 2-port for now

Cheers



Iain

john banks

Clean it.

iain atkins

John,

I had mistakenly put the actuator to the top vent, and the compressor side (from turbo) to the 90 degree port (i.e. just round the opposite way). Would this have caused the problem?

I now have the actuator to the 90 degree port, compressor side to the top vent, and the vent to atmosphere off the bottom vent. Haven't tested yet, will do tomorrow.



Iain

iain atkins

BTTT

Bob Rawle

Compressor (turbo) outlet to top port, actuator to side port, air intake (vent) to lower port.

iain atkins

This is really annoying now.

With both solenoids i'm getting a 2.5psi spike (have now got the pipes correctly connected on the 3-port). 3 port definately has more control and gives better spool-up, but still spikes by the same amount.

With the dawes, i'm getting a 2psi spike, and boost oscillated a bit

Connected the wastegate directly to the turbo outlet and boost went to 8psi (or there abouts).

Checked the dumpvalve and all appears to be correct (genuine subaru valve)

Two weeks ago, it was going straight to 17 psi and holding with very little overshoot (1psi at most).

Any pointers??? Or has my boost control been possessed

Cheers



Iain

PS. If bob or john could mail me their number, it might be better to actually talk if possible

iain atkins

Could my wastegate be faulty, even though it opens at 8psi?

Cheers



Iain

john banks

You need to alter the restrictor or use a restrictor valve to get the delivery of the 3 port solenoid's control correct.

iain atkins

Thanks John

I have already tried that though (used the festo valve on the bleed off side). If i took held boost past 14psi (by opening the restrictor) it would then spike again.

I have a feeling that there maybe something else wrong, as whatever boost control i use i'm getting the same spike. I have checked all boost hoses for leaks etc and rmoved intercooler to check for any abnormalities there.

The worst spike occurs at 3,000rpm WOT in 5th gear. Spiking to 19.5psi , then holding 15ish (on 3-port) and 16.5 (on 2-port).

FCL defend voltage is 3.76v to 4.2v.

Cheers



Iain

john banks

Too high a defend point would account for spikes, too low would give high held boost. To make a closed loop control system with a fuel cut defender you really need the type that alters the slope rather than puts a notch in it. This way you just change the boost target that the closed loop system works towards. So if you want to raise held boost from 14.5 to 17.5 PSI then you need to make 17.5 PSI appear to be the same voltage as 14.5 PSI. It really is a lot of fiddling and you would be better using a Dawes if you are struggling!

iain atkins

Thanks John,

So let me get this right. . . . . . . .

If i set the defend zone at 3.8v to 4.2v this would be more spiky than from say 3.5v to 4.2v.

Would i be better off with an HKS FCD?

The reason i don't like the dawes is because if there are any problems then the ECU has no way of reducing boost.




Iain

john banks

Get a knocklink then. Don't trust your ECU to kill det on a modified engine IMHO.

iain atkins

Had a bit of a brainstorm this morning.

I remember about a year or so ago, i had a problem with my map sensor and boost shot up to 20psi in 5th gear (without FCL). The sensor had gone faulty and was only working up to 3v.

So with that in mind I'm now tempted to try defending from 3.78v (1bar) to 4.2v. This should allow the ECU to see a bit more boost and therefore 'grab' hold of the spike a little bit better, and lessen it.

Could too low a defend point account for the boost spikes?



Iain

[Edited by iain atkins - 2/10/2003 9:33:14 AM]