davers

Im quite new to this forum,

I bought my 1st imreza last week, a 97wrx, all was fine until taking it for its maiden run down the A49, full tank of Shell V-Power and off i went, when the car was mid way through boost it would just cut and then come back in, like a violent misfire. Was like hitting a brick wall and then coming out the otherside.

Was doing it through pretty much all gears if i was flooring the throttle. So takes it back the next day tells them about it, leaves it with them, they cleaned the solenoid out and said theyd replaced the actuator, but after the mechanic took it out it was still doing it. Eventually they found that one of the wires in the Cat 1 they had fitted for me wasnt soldered properly and waa arching out. So this was fixed.

And it was fine. Until yesterday. Started doing it again but only in 4th and 5th when my foots planted. So need to go back down there again tommorow.

From my experience with cossies and rs turbos to me its the actuator.

Anyone had experience of this, i found a video on youtube of a car actually doing it.

Thanks

YouTube - STi Pull #4 Overboost

jsh1

iTrader: (1)

My 96WRX did it for a few test runs when we were adjusting actuator. Anything over 1.1bar and it hit fuel cut, backed the actuator off a bit and it has been fine since.

Might be worth getting a boost gauge and seeing what boost you are running.

Not sure what else may cause it.

Jason

StiX

iTrader: (4)

Mine did it, was a split hose. Replaced quite a few hoses as they were quite brittle and it was fine.

Until one of them slipped off - and it did it again, small jubilee clip later and its been fine since.

So check all the hoses really carefully.

dan83590

Is it standard or do you have a boost controller fitted?

davers

Would be a good idea to fit a boost gauge, the garage offered to wind the boost back a little but i declined, as didnt wanna loose power. But may well be the cause of the issue.

StiX - actually good point, will check all the hoses over.

Dan83590 - its standard jap import. However i think something may have been taken off, along the lines of a boost controller, as next to the actuator is a clear tube which seems to connect to nothing but has been closed with a tie rap.

Will upload a pic.

dan83590

That'll definitely be the cause. At the moment you have no power as when at WOT your car cuts the fuel! And there should definitely not be a cable tie holding a hose closed. Find out where that hose lives matey.

The reason you only hit fuel cut in 4th and 5th is that the car does not reach true full boost until WOT in these gears.

P1SWRT

iTrader: (2)

sounds like the oil level has been overfilled......boost solenoid is sticking open as a result from the oil vapour collected around it. engine management thinks that its overboosting and shuts down the engine.

not quite as untechnical as that but along those lines...

does it around 4,000rpm??

dan83590

Do you not think the cable tied hose may have somthing to do with it then?

davers

ive heard about this happening after a service if the oil is even slightly over the "full" point. Thats come up a few times when ive google'd this issue. And yes between 4 and 5k.

But yes, this cable tie may have something to do with it, i will get a pic tommorow and upload it. If its been tied up, i asume it will be to stop this happening, but when the engines at full boost as tight as that cable tie may be i cant see it beeing 100% sealed.

billyray911

iTrader: (4)

I had the same sort of problem-just like hitting a brick wall then went into limp mode.
My tuner hadnt fitted the coil pack properly.Refitted-no more problems.

dan83590

Get a picture uploaded and lets stop everyone making stabs in the dark (this includes Moi). It's only gonna make you confused to hell. You will have 101 different answers and all will be bo!locks....

davers

here we go got some pics. And 1 of the car itself while i was at it, as im new to this forum.

dan83590

Looks like there used to be a boost gauge fitted to that pipe. Whats at each end of the hose the tee piece connected to?

dan83590

Also check here Boost Solenoid Plumbing

You should have this on the inner wing, drivers side.

davers

you know what i think that brass part it mentions has nothing on it. when i was under the bonnet today i noticed it and thought.. that looks like it should have something connected to it. Dont get me wrong im new to scoobys.. im used used 2 old pinto engines with carbs or cossie motors.. but it just stood out as something that didnt look right

dan83590

The brass pill would be inside the bottom hose off the Boost Solenoid. You think the brass restrictor is missing from the bottom hose? If you pinch the hose you will feel it. Pinch down the whole length.

If it definitely isn't there then the dealer will be able to supply you with a new hose, and the restrictor which just pushes inside the hose. Should be £30 ish.

Thing is, you say that it only fuel cuts in 4th and 5th. If the brass pill were missing the car would over-boost all the time, in every gear as soon as your foot was on the accelerator. Are the hoses from the boost solenoid all standards items?

sti-chris

my scooby was hitting fuel cut after a decat and remap , the car only done this in high gears when under load and full throttle.

a few tweeks to the map and all was well.

davers

got a couple of pix to upload when i get in work.

it was cutting in all gears when at full throttle, but now after the garage had it for a day its only really doing it in 4th and 5th.

that t-peice, one end goes into the manifold and the other end into somewhere else. il upload some pix later and to be honest im going to go back to the dealer again tommorow.

dan83590

The dealer needs to do a bit more of what he already did

Let us know what the fix was please.

davers

Here the brass part i thought you meant.. this is the turbo outlet isnt it?




I followed the T-Piece and heres were it goes


One end goes into the inlet manifold


and heres were the other end goes (centre of the pic)


Goin to the place tommorow, i dont want them to wind the boost down unless its boosting over what it should be (1.1bar). Possibilities from what ive found from here and the net, too much oil, faulty actuator, boost solenoid plumbing.

B4D HK

iTrader: (15)

mate you are running to much boost thats why you are hitting the fuel cut. turn it down or fit a hks fuel cut defender. but be carefull these old wrxs dont like the boost being turned up without supporting mods.....you have been warned..........

CHRIS575

i had same prob with my sti as a newbie to the impreza world but as a master tech i followed everyone advice as listed all the above in the end i found my dump valve piston was seized in chamber so i stripped it down fitted new piston and spring. also gave car a service oil and filter and new plugs since then she is flying . if your not using v power would check your plugs because they will get to hot and brake down / piston melt can also happen in long run. def check plugs ngk plats and dump valve /if dump valve stuck closed as mine was cause overboost!!!!!!!!!!!!!!!!!!!!!

dan83590

That is the boost control solenoid. And judging by the lack of a hose on that nipple I'd guess that your car is fitted with a boost controller of some description. If so it's a simple case of turning the boost down a little. If the fuel cut is only now happening in 4th and 5th the boost would only have to be turned down a smidge, you wouldn't notice the difference in power.

You could fit an Fuel Cut Defender but that wouldn't repair the cause of your over-boost! Imprezas run a bit rich so you can up the boost a bit without supporting mods (you would need a fuel cut defender). People blow there engine to bits when they increase boost without monitoring the results correctly.

If you do not use V-Power, don't worry, the world will not end.

davers

thanks alot dan really appreciate it. Will be popping in the place tommorow so will leave it to them to do.

Another question as you seem to be the man in the know, when i plant my foot, and the boost winds up, obviously you can hear the whistle of the turbo, but theres this roaring kind of sound that increases with the boost, now it sounds awsome, just goes ROARRRRR, it only does it when i plant my foot and the turbo comes in. What is that noise, induction, i thought maybe the diffs locking, dunno.. justy intrigued really.

If youve ever heard an vulcan bomber it kinda sounds like that when it opens the taps.

dan83590

Could be lots of things. Without hearing the noise it's impossible know. I'd guess at an induction kit from what you said though..

sponners

iTrader: (4)

would NOT recommend fitting a fuel cut defender as this is only 'masking' the problem and will cause the car to run lean......which could be very dangerous.

just turn the boost down or get a remap

uk300scoob

iTrader: (24)

have you checked your air intake or air box what ever you have installed on your motor can be down to a dodgy air flow meter aswell that has happened to me before.

davers

havent been in this week end as been mega busy, however im of 4days this week so will do then.

As for the intake, its on a standard airbox and filter. i decided against a induction kit as ive heard it can cause problems with the airflow meter. Ive considered just getting a K&N panel filter or a Blitz one

joz8968

iTrader: (13)

Mate, that hose is going from your inlet manifold to the OEM fuel pressure regulator (see circled, above). So, if that cable-tie isn't holding the tee'd off hose totally closed, then that T-piece could be bleeding off the vacuum! This will affect the fuel pressure and no doubt upset the way the car runs.

Before you investigate the boost control system, I'd definitely get a brand new length of vac hose and replace that whole lash-up (failing that, at least dispense with the T-piece and replace with a straight-coupler), so that the FPR will get to see the full vacuum!

It simply might be all you need to do to solve your issues...

davers

Ok well its been fixed

Took it down to car planet in warrington were i bought it from. We fitted a boost gauge to see what it was running and took it up the road, the problem always happens at 4,500 rpm in 4th and 5th. So off we went up the road into 4th plants the right foot and it only got up to 3,500rpm and the boost gauge read 1.4 bar!!!!! so we double checked the boost gauge and fitted another to make sure.

And again, only got to 3,500rpm and was running 1.4bar.. so didnt even need to get it to 4 and half..

Boost has been wound down now and the solenoid etc has been changed over too and the problem has now gone. Ran it right past 5k in 4th gear and 5the motorway and hasnt done it since.

Only problem.. car seems a bit pedestrian now, quick obviously, but not 1.4+ bar quick.. but hey i dont wanna blow the thing up. However, i would like to tune it so it does have that crazy power again, but do it right, 2.5 coversion seems all the rage. So time to abondon this thread and look at reliable power upgrades, but before any of that.. some brembos!