After rebuilding my engine and fitting a vf28 turbo, I`ve found it wont boost over 0.7 bar, but my Ecutec map is for 1.2 bar, which it happily made on the standard td04.
Now, after investigations we found it will boost right up (saw 1.5 bar) with the actuator held closed, so changed to another vf28 actuator and it still does the same........0.7 bar only!!?

We by-passed the boost solenoid, no change, added a bleed valve, no change, BUT, when we clamped one of the vacum pipes off the turbo it`ll boost up okay again?

Anyone got any ideas whats going on and a solution?

cheers

Cliff

 

There should be a restrictor between the compressor outlet and T-piece (which splits it to go to the solenoid and the actuator). You could try using an in-line restrictor valve which will then adjust the peak boost achieved. Make sure that your fuelling and timing are suitable, but a TD04 boost control map is suboptimal for a VF28 even with such adjustments because it will drop the max duty before the VF28 has spooled and will drop the boost targets at the top too quickly. Additionally, you may have way too much ignition at the top. Best to run it at 0.7 bar until mapped IMHO unless you know what you're doing.

 

Blimey, im sure my mechanic will know exactly what you are on about, but that was way too technical for me and went right over my head
Im getting Paul at Zen to remap my scoob and he`ll be fitting my new STi injectors at the same time, but I was just making sure everything was in working order before the big day so as not to have more expense that I cant afford

 

The restrictor is a small piece of brass with a hole drilled in it that sits inside the rubber pipe that John has described.
If you are using the pipework from the VF28 it 'should' have a smaller restrictor then the TD04 pipework.

I think the VF28 uses a 0.9mm hole and the VF28 a 1.1mm hole

It will overboost using the VF28 restrictor, but it sounds like you don't have one at all.

I managed to run 1.2bar on the VF28 (with good fuelling and no det) using the TD04 restrictor on a TEK2 ECU. But got it remapped to 1.3bar a few weeks later.

 

great, but does the td04 use a 0.9mm or 1.1mm hole?




Cliff

 

AFAIK the restrictor doesn't affect the ECU's target boost, because it controls the boost solenoid to do that. However it does make a difference to how quick you spool up and what sort of overboost you get. I THINK mine (a 98 WRX wagon with a TD04) was 0.9mm then I slightly drilled it to 1mm or just over. THing is, I can't remember whether it spiked and dropped back to target boost faster or slower once drilled out! Logically the bigger the hole, the faster the boost signal gets through, so a smaller hole will allow less spiking effect?
I'm confused now.

I know when I accidentally got a couple of the boost solenoid pipes wrong I lost half of my boost totally, then by plumbing them right again, it all came back.

 

Just checked my pipes and I cant even find a restrictor!! Maybe thats part of the problem?!

 

Pull it all off and throw it in the wheelie bin and fit an EVC, safe as houses and makes target boost a lot quicker than OE stuff, I use an HKS EVC V and you know what my car goes like cliff

Plus I am running a VF28 too

 

If I had the money then yep, i`d do it, but I haven`t so I`ll have to get a restrictor and whoop your *** anyhow

 

Cliff you shouldn't be trying to run any major boost without a remap or you will be having engine problems again

 

I know, I just wanted to see if it would boost so Im happy everything is working before I take it in for the remapping.

 

It will effect target boost if it's not there.
Just 0.1mm difference made a target difference of 0.2bar on mine.

The VF28 has the smaller restrictor

Running the 0.9mm VF restrictor made a 1.2 bar mapped ECU, run 1.4 bar
Opening it up to appox 1.0mm dropped it back to 1.2bar

As mentioned above it was a TEK2 ECU and ran without knock. It was running 296BHP when I took it into PE for the remap.
PE commented that it would run like that no problems and the advance multiplier had only dropped a small amount.

Although I was playing it safe and got them to sort it.

 

this should be interesting cliff

 

Right, got the restrictor now, can someone just confirm that it goes from the end of the compressor housing to the t-piece, rather than from the actuator to t-piece?



Cliff

 

compressor housing to the t-piece is correct

 

Confirmed....

 

While you may think this isn't logical, it is when you realise that the hose barbs on the vf turbo are angled differently to the td04, and that the original hoses on the TD04 fit nicely the wrong way round on the VF24.

Paul

 

SORTED

Thanks to everyone There was NO restrictor in any of my pipes, not sure why, obviously got lost/fell out on the rebuild and turbo swap, but Its now in place and all working fine

I love it when a plan comes together



Cliff

 

about bloody time cliff, now get the f**ker remapped for christ sake!

 

Money is my last obstacle now, anyone got any ideas on this technical issue?

 

nope as i suffer the same way

 

Cool, glad that was easy(ish)

 

I LOVE SCOOBYNET

 

we love you

 

PMSL

my thoughts too

 

someone drop round the 400 quid and i`ll be there in my blue rocket quicker than I can say "300 club here I come"

 

can any body tell me where to get a drwing of how the turbo is fitted correctly as i have a problem with mine too and i'd like to check the plumbing !! i bought my 95 wrx with turbo blown still having a few problems?

 

My95 is different to the above as you have a 3-port boost solenoid.

It should be plumbed as follows :

1. Turbo outlet nipple connects to Top port of 3-port boost control solenoid
2. Acutator connects to middle port of 3-port boost control solenoid
3. Bottom port (out of base) of 3-port boost control solenoid, connects to a nipple on the air intake expansion box (the big black square thing)
4. In the vacum hose describe in No.3 (above) there should be a brass restrictor with a hole of 1.2mm IIRC in it. If this isn't there the car wil over-boost.

 

nice one scott, cheers