6A12TT Help Required

[ukbiker]

Hi guys, Am new to the mitsubishi scene. Recently sold my skyline gtr for a rare R1 motorbike and cash, And have now managed to pick up a rare jap import galant sport gt 2.0L twin turbo ( All in dark blue instead of that nasty white and blue!) , The vehicle has a boost tap fitted and boost gauge, Also the previous owner has drilled big holes into the air box as a cheap method of more induction i suppose. I know how much manual boost controllers via a boost tap is dispised against due to the dangers of boost spike etc. But considering i picked this car up for £400 for a twin turbo with only 45000miles on the clock i dont really fancy paying for a fancy greddy boost controller. Anyway, to get down to the point of me posting in this section is, With this boost tap fully unscrewed to its max, I am boosting at around 12psi, Ive read elsewhere that you can boost to 15psi at a max before the turbos start panting for air. Im unable to even get above 12. I know i have no boost leaks etc. Even removed the tap so it was not restricted but still only boosting to 12. Ive drawn a little diagram to show how its piped up, As im not clued up on this engine im unsure as to if its piped up correctly or not

There is a 4way plastic pipe joiner (shown in pic), with one of the ports on it blocked off, The T piece tap governs the leak for the actuators to allow more boost into fooling the actuators of the signal pressure, Now My problem is, with the tap fully open, Im only getting 12psi of boost, Does it look as tho its piped up correctly from looking at this crude picture ive drawn( Note when i screw the tap in, It does reduce my boost). Or could it be restricted by those tiny metal pipes that run above the throttle body which connect to rubber pipes heading to the actuators?, If this is the case would buying some decent pipes to run directly from both actuators to the Tap and 4way pipe joiner whilst bypassing those small metal pipes above throttle body increase the boost? As im wondering if my only restriction right now is down to them?.
Thanks in advance
Craig

[Goku]

Are you sure the tap is facing the right way ?

When you put a boost tap on, it should never lower your stock boost. The stock boost is determined by the wastegates on the turbo's, so when the tap is fully open, it should be running at stock boost, and as you close it down it causes a restriction and tricks the wastegates into thinking there is less boost than there actually is running to the turbo's.

It looks as though it's plumbed into the right place, I'm assuming that top box is the pipe to the intake manifold ?

As for the small metal pipes, there are one or two you can by pass if you wish, but there is not gain in doing so really.

[ukbiker]

Hi goku, When i said i can reduce the boost when the tap is screwed in, I mean this by as i screw the tap down creating restriction it returns to stock boost, When i open it fully i recieve 12 psi of boost, I thought the method was, tap fully open gives you more boost as its creating a leak there fore if your wastegate has a freshhold of say 7psi, and the intake manifold is now pressurised at 7psi, But the tap is inducing a leak of say 1.5psi then the wastegate actuators are only seeing 5.5psi down the signal line from the manifold because of the tap, therefore allowing the turbos to spool up more than 7psi.
I thought that possibly those small metal pipes are causing a natural restriction of around 12psi because of there size, Also i could be restricted by the actual hole in the tap. hmmmm


Forgot to mention, These actuators arent piped up to any standard solenoids etc to give me a boost cut etc

[Johnathansgalant]

I saw u on the other forum but i wrote this there too.
try removing the boost controller for now and see how much stock psi is that way u will know if u r increasing or maybe decreasing boost because u have it on backwards or a pipe is the wrong way... usually u screw clockwise to increase boost and counter to decrease... In otherwards u put a screw further in to blow flow and divert it to a hole that will create a leak and the further clockwise the the more its blocked creating boost... reverse is for counter.. When u fully are counterclockwise u remove restriction and should have the lowest boost setting or stock wastegate setting.. there are some controllers that vary but this is the jist...

[hk20000]

don't bother I'll tell you right now the actuator spring boost is 0.4BAR i.e. 6psi.

my car was like that too at a point mine didn't even have those mickey mouse manual boost controller the factory boost solenoid simply decided to crap out.

so I went Greddy. Installed it over an afternoon and I'm doing 16psi easily.

Also check ECU for any knock recordings, according to the Japanese repair manual, the ECU will stop boosting if it sees knock (Brit gas is not 100RON I don't think?). That's your solenoid right there going wide open, and that won't help at all.
Clear the code (knocking will not trigger CEL on dash, btw) and try that. Next up, remove that damned tap. Third, on the rubber hose between the solenoid and the throttle body (the 4 way you were talking about, right?) has a restrictor on it from factory, simply pulling that away and a healthy factory solenoid should push your max boost from 0.7BAR to 0.9BAR (12.xpsi).

Basically what I'm saying is return the setup to factory to check factory equipment for faults first before adding that hack job there to make diagnostics difficult. You are dealing with a rat's nest of vac pipes on a DOHC V6 you know.

If factory solenoid failed then the only real fix for you is a EBC.

[Goku]

Actually the stock boost is between 6 and 8 PSI, it just depends on how old the car is and how well it is running. Mine from stock is 7.5PSI and I have seen others that are as low as 5, but everything was running fine.

Also, if you have a manual one with the blue tabs, you can boost up to 22PSI though they're not happy at that point. the Auto turbo's can only take up to 15.5 PSI, thats the max they can flow before they run out of huff.

[hk20000]

factory boost should get up to 0.7BAR and then taper to 0.4 near the redline....

unless I had witchcraft on my car before. Also the manual turbos are out of huff at 16psi as well according to Greddy's spec sheet for TD025L.

[Goku]

I have seen the blue tabs do 22 quite easily, they are happy enough at 16 though, you could run them at 16 and be fine :)

[ukbiker]

ok glad to find people knowing what there talking about :), Hard to find decent info on these engines!. Ill take a picture of all the items ive been talking about and post up, including how its all plumbed in, as my picture is quite rubbish!

[ukbiker]

Here ya go, This is how i recieved the car, Could someone explain to me if its piped up correct, that 4way block is what connects both actuators, 3rd port is to tap and inlet
4th port is blocked off

[Johnathansgalant]

what happens when u screw that controller in all the way?? You should buy a better manual controller by the way. That one doesnt look like the best to be using u need quality boost control..

[Goku]

^^ what he said

Another option to see if it does go above 12PSI is to free boost the car, if it doesn't go above 12PSI at that stage, either something is broken or the turbo's are stuffed.

[hk20000]

LOL you do know your boost solenoid is UNPLUGGED right? That thing next to the ECU boost sensor...

how is the car going to run properly like that I don't know LMAO.

Consider yourself very lucky:



The T is for the boost gauge.

From what I see you need to revamp EVERYTHING in there to get it going.

[ukbiker]

Hi hk20000, Ive attempted to pipe up in a similar manor to your's, Im guessing your boost solenoid is from an electronic boost controller as its different to what i have, Im asuming from that solenoid, the black pipe leads to a T piece which at both ends leads to a turbo actuator, and the blue pipe coming from ur solenoid is your inlet pressure feed. Ive piped mine up pretty much the same, Between the inlet pressure feed and solenoid i have the tap fitted, and the other port on the solenoid i have my 4way block with one port blocked off in turn creating a T piece similar to your own which recieves both pipes from the actuators and then to the solenoid. Now after driving vehicle with it being piped up like this, I still recieve 12psi with tap open (even if i remove the valve from the tap it still only boosts at 12psi), With the tap fully screwed in i recieve stock boost which is 8psi. HMmmmm, Im stuck! Is that 4way block factory fitted part? if ill replace that for something much larger and better
Also How do i go about checking for/removing knock readings from ecu.


(just so theres no confusion about this tap, screwing in creates restriction and eventually seals off, Unscrewing removes restriction and allows it to leak through bottom of tap via a hole, The part that screws in has a tapered end on the bottom of it within the tap that sits within this hole when fully closed sealing the hole and also sealing both ports on tap from breathing)

[hk20000]

there are no 4way blocks from factory.

no matter how you think of it the actuator shouldnt be connected to manifold pressure directly...that is the bottom line.

[ukbiker]

Ok, I have it piped up exactly how the japanese diagram shows under the bottom of the bonnet (only noticed it today), Its boosting at 13psi max now, possible its either ecu needs faults removed or shagged solenoid then

[seth98esT]

Im no 6a12tt expert, but you dont need the stock boost solenoid if you have a manual boost controller. The boost solenoid controls the boost above what the wastegates are set to.

The ECU shouldnt have anything to do with the amound of boost if you have a MBC. If you absolutely cant get above 13psi, Id say you have a big boost or vacuum leak.

[ukbiker]

While this post has gotten allot of attention, May i pick your brains on this too, On deceleration from around 40/50mph to 0 i get a odd noise, Like a rubbing noise that slows down with the speed on the car, Dipping the clutch doesnt affect the noise, Nor does it make any difference as to what gear im in, Even coasted in neutral But still does it. I tried replacing gearbox/Diff oil's but still no change. Any ideas? I also get a odd knock from the Right front area of car, But ive checked my joints with a bar and they seem fine.

[Goku]

Im no 6a12tt expert, but you dont need the stock boost solenoid if you have a manual boost controller. The boost solenoid controls the boost above what the wastegates are set to.

The ECU shouldnt have anything to do with the amound of boost if you have a MBC. If you absolutely cant get above 13psi, Id say you have a big boost or vacuum leak.

Most people do bypass the stock solenoid and usually end up with big problems of boost spiking and the car not running properly. It's just something the 6A12TT's seem to do, not all of them mind you, but most of them.

As for the leak, that might also be true, but surely he'd hear it leaking if it were that bad ?

[ukbiker]

Regards to hearing a leak, When the engine idles if i lean over the inlet manifold you can hear a kind of shhhhhhhhhh noise but ive just assumed that, that noise is the sound of the air rushing into the manifold. It doesnt sound like an external leak. Do all 6a12 engines make this noise, If not then i probably do have a leak somewhere by the rear turbo.
On another note, On deceleration i get a wierd whineing noise from the front sounding like transmission/diff. But it only seems to be prominent from below 25mph(not 40/50mph as i previously said). The noise sounds like a wa wa wa wa wa wa wa noise. This whine slows down with vehicle speed not engine revs etc. as stated before, Dipping clutch or coasting makes no difference. I do hope its is normal and not a diff/gearbox on its last legs?. Not sure if this could be contributing to the problem but my offside rear shock top bush has had it, so i get a knock even on the slightest bump