GazJenno

I keep over boosting in 3rd/4th nd 5th... got a full de-cat exhaust, K&N panel filter and a chip which is meant to account for de-cat and filter.

Its only been doing it since I switched my Version1 Intercooler for an STi Version 1 intercooler (very slight difference in size) and fitted free flowing samco turbo hoses... these are most likely the cause but surley fitting samcos shouldnt cause this.

Has anyone else had this problem???

its very annoying and I will appreciate any help please.

thanks
Gaz

Scott.T@PolarPerformance

if you replaced the boost control pipes with samco/silicon hoses you may of removed the restrictor that fits inside the pipe on the bottom of the boost control solenoid.

If you havn't switch the pipes it's still worth checking the pipe is there and it still has the brass restrictor inside, as quite a few seem to have these removed, especially if an induction kit has been fitted.

GazJenno

Cheers Scott, I havent changed the ones you showed with silicon tubing just the Turbo-IC pipe and IC-TB pipe with samco ones.

I have already Tried a few things but nothings helped

First off ECU restet after fitting the new IC and pipes
Cleaned out the boost solenoid and the pipes you showed (the brass restrictor is still there)
Was going to adjust the wastegate actuator arm but its non-adjustable on my turbo

Is it likely the free-flowing samcos and alloy pipe on the STi IC are causing this even know its only a slight difference.

And how can I over come this? small brass restrictor?

Scott.T@PolarPerformance

Do you know what the fuel cut limit is set at in the chip and what it is boosting to now.,
the intercooler may have a slightly smaller pressure drop accross it and hence cause a bit more boost to be generated. But I doubt it's enough to trigger fuel cut unless you were very close to hitting it beforehand.

A smaller restrictor would solve it yes.....but it doesn't really fix it (if you get what i mean)

GazJenno

Yea I get what you mean it would just be hiding the problem. The chip is set at around 16 psi and fuel cut is around 18 psi. I have hit the fuel cut pressure before but that was when the oil level was abit high and since sorting that I havent had it since, untill I replaced the IC and Pipes.

Maybe one of the pipes are leaking or the IC pipe gasket is leaking, would that cause it?



Gaz

p.s. Tonight when I tried to adjust the actuator arm only to find it wasnt adjustable I took the pipe off that has the restrictor in it to see if was there and from your picture I think I fitted it backwards...havnt driven it like that yet but will it make any difference?

Scott.T@PolarPerformance

Do you have a boost gauge i.e have you seen that pressure or could it just be coil pack failure causing a misfire.
Is the chip one of mine ?

sl1000

especially changing the turbo intake hoses for samcos will result in a different spool-up characteristic. The chip is not able to control the boost accurate enough during spool-up thus boost spikes and finally fuel-cut.
You could try different restrictors or fit seperate boost controller.

GazJenno

yea I have a boost gauge and it does hit 18psi... dont think its one of your chips, I bought it off someone on here... yours is more of a board with a couple of chips on it right? This one is just a single chip... was told it ups the boost, allows for a decat, and panel filter and for 97octane fuel?

It does spool differently, earlier if anything and make more noise... even the dumpvalve is louder so there is obviously more air in the system. Would rather not go down the manual boost controller route though.

Scott.T@PolarPerformance

The change would be minimal with the samco's
If the chip is set up well enough and everything else on the car is correct then just changing a couple of hoses would not of affected it.

No way would it cause a 2psi increase in boost.
A split hose on the boost control side would though as it would act like a bleed valve.

P.S I do supply single chips. Is there anything written on the label ??

GazJenno

well the car runs perfectly every other time its just when I go full throttle and at higher revs, if I keep off full throttle just slightly it holds 16psi fine.

More investigating needed I think. When you say a split hose on the boost side do you mean on the vacuum pipes or main turbo pipes?

do you know if putting that pipe with the restrictor in it the wrong way round will make things worse because I will switch it back around before I use the car again if it will, cant see how it would?

I'm not sure whats written on the chip, I will have to have alook... can you find out? do you do the mappable boards too? and would you part ex?

Gaz

sl1000

Scott changing the turbo intake hose on the subaru results in a different spool-up characteristic.
The parameters for the boost control within the ECU/chip need to be adjusted. If not the boost control becomes more unstable resulting in boost variations. This can easily cause overshoots of 2psi or more.
Seen it from experience but I could easily correct it because of seperate boost controller.
btw 2psi increase are not just directly caused by less restriction in samco hoses.

sl1000

18psi on a split hose?
don't think so

samco with slightly closed throttle = standard hose / IC with full throttle

GazJenno

Oh yea good point thats me re-introducing the restriction the old IC hoses gave I guess

GazJenno

Could the MAF sensor cause overboosting? Can it be cleaned with carb cleaner...would you just spray it to clean it or will this screw it right up?

Any one got any other ideas, or a spare boost controller I could borrow to see if that works?

Gaz

Scott.T@PolarPerformance

sl100....agree changing the turbo intake hose would cause an issue....
BUT he hasn't changed that hose only the turbo to Intercooler and Intercooler to Throttle body.

If as car is mapped to 16psi and there is a split in the hose that connects from the engine to the map sensor it could quite easily overshoot the target by a couple of PSI.

Don't worry about the MAF....

Omen

Swapping intercoolers or moving them about often dislodges crap in the pipes which travels down and gets stuck in the solenoid - causing overboost.

Have you tried putting the car into test mode with the ecu connectors and then cleaning the pipes out connected to the solenoid with brake cleaner?

Sorted mine out straight away.

GazJenno

is that the long one that goes from the inlet manifold to just above the boost solenoid? If it is I think I did change that to a silicon tube item...will check out that hose just incase.

Have tried that to a degree but will go over some of the pipes again I think.

Cheers

Gaz

Scott.T@PolarPerformance

No, I think Sl100 was refering to the induction pipe from the airfilter/MAF to the Turbo, that is an upgrade for the later models with a straight entry turbo.
You will have a 90 degree entry with a 90 degree elbow hose to the MAF.

GazJenno

Yea thats right, I havent changed anything before the turbo except for a K&N panel filter... Its just you said "split in the hose that connects from the engine to the map sensor it could quite easily overshoot the target by a couple of PSI." Just trying to figure out which hose you mean???

Im gonna check everything again and see if I can find anything

Gaz

p.s. In the future I would go for a re-mappable board, would you part ex my chip after checking it out that is, just woundering anyway.

Scott.T@PolarPerformance

A split in any of the hoses that connect to the boost control solenoid or map sensor (black thing mounted next to the boost control solenoid) could potential bleed air away and cause the ECU mesaurement to be false/low hence why it would overboost due to the ECU compensating on the boost control.

Re : chip...sell it...you'd get more money then I'd give you for it ....

GazJenno

just another thought... I have my boost gauge plumbed in to the hose that goes from the Inlet Manifold to the MAP sensor, is it possible that due to there being more pipe work to fill and a T-piece to cause some disturbance it could make it spike??? Just trying anything now, cant see any split hoses.

Should I plumb my boost gauge into the DV feed instead? just to see if it makes any difference?

Gaz

Scott.T@PolarPerformance

On my old MY94 (going back a few years now......)I had the boost gauge plumbed into the middle hose (of 3) that come off the inlet manifold, as per an old Scoobymods thread
FITTING A BOOST GAUGE

Omen

Yep, I would try the brake cleaner before anything else expensive. Give the solenoid and pipes a glood flush out with the stuff. Was an instant cure on mine. All i had done was take intercooler off to fit a knock link - and put it back on again.

sl1000

Ah that clears things.
it is sometimes difficult to correctly understand what people mean on Forums.

So

yes was talking about intake hose from airfilter to turbo inlet.
and yes agree if vacuum hoses have leaks than this might lead to these boost control problems.

craigmk2crx

Hi

not sure if this helps with my motor not being a scooby!!

A few months ago I changed my HKS induction kit for a K&N induction kit on my Evo V. Mainly due to the fact that the HKS had been on there nearly 8yrs.

As soon as the K&N was fitted I was getting overboost & fuel cut at about 5k rpm. At 1st I didn't know what it was & totally sh*t my pants thinkin the engine was gonna burst out of the bonnet

Anyways, i refitted the HKS & everything went back to normal. So made a few enquiries with Evo tuners & on the forums. 99% of people said it'd be the actuator so got it booked in at a nearby Evo specialist for it properly checking out. I refitted the K&N before I went so they could test it properly.

Did turn out to be the actuator that was on its way out. The new filter was allowing more air through so showed up the problem before the HKS filter. Was told it'd happened sooner or later with the HKS when the actuator totally buggered up.

Since having a new Evo 9GT actuator fitted i've also had to drop my high boost setting from 1.25bar to 1.2bar as I was still getting overboost with it set at 1.25bar.

Like I said, different car but principles should be similar Hopefully it may help. If not good luck with sorting it out


Craig

GazJenno

Cheers Craig, you might well be on to something there... My actuator does look abit knackered, it looks as if its burnt from the heat of the turbo and half of it is rusty looking, the half thats under the heatshield.

I did suspect it could be this but I can move the arm by hand so didnt think much more about it. Maybe, like your, its sticking just slightly but enough to cause slight overboost.

Anyone know where to get an new one for a TD05 and how much roughly it would cost?

Cheers,
Gaz

craigmk2crx

Glad to be of "possible" assistance

Luckily for me the actuator is a common prob for the Evo V/VI so it's pretty much that nearly every time.

The actuator is sat right at the front of the engine right behind the grill. The weatherproof diaphragm is commonly known to be weak on the V/VI so they just go t*ts up after a while with all the water & crap that comes through the front.

A lot of people go for newer model actuators, like I did with the Evo 9GT model as they're a lot stronger/durable.

I sometimes still get overboost when i'm running at 1.2bar(high boost mode) but it's only usualy late at night when the air temp is cooler. I'm finishin my exhaust of soon with a 3" downpipe & decat shortly followed by a remap & uprated FPR so should be running perfectly after that. Want it all doing now but can't cos I go on hols in 4 weeks so can't spare the £


Craig