samtothed

Hi all, first post here!

I picked up a MY99 Turbo 2000 on Monday. I have a problem though, at WOT I am getting pulses of boost on and off. This mainly only happens at above 60mph, I put my foot down and I get rapid acceleration for maybe a second, then no boost, then full power, then no boost, and so on.

I did some reading on here and read that it could be the BCS that needs cleaning (I will try that tomorrow), I have inspected all of the vac hoses and they look OK.

I have a PSI3 ECU Data Monitor in the car, at first I wasn't getting a boost pressure reading, but after some fiddling with it I found that it wasnt set to read boost from the ECU, so I corrected that and went for a drive.

When I plant my foot, it boosts up to a peak of 17.3psi! Then fuel/boost cuts and starts pulsing with boost off and on. At one point I saw 18psi peak.

This is bad I would assume. What are the causes for this? I would have thought a jammed wastegate?

Modifications are as follows:

P1 exhaust
Sports cat
Xtreme downpipe
K&N cone filter
BOV
Remapped to 241bhp

I have read that it could be because the exhaust is too free flowing, but the exhaust and remap was done in 2005, so I doubt that it would have been driven like this since then.

There IS a "pill" in the vac hose. Don't know the size of the hole though.

Tomorrow I am going to inspect the van hoses more carefully and put the car into test mode and flush the BCS and vac pipe work with brake cleaner.

Is there anything else that it could be? How do I test waste gate? Could a boost leak cause this and how do I check that?

Also I would like to add, it has been recently serviced and no the oil level is not high, in fact it is almost too low!

Many thanks in advance! Great forum BTW!

Sam

samtothed

PS. PSI3 shows zero fault codes recorded. Also tried a ECU reset.

Could it simply be the cold weather? On the motorway above 60 it is most aggressive.

keljon

iTrader: (10)

clean the boost pipes with the test plugs (under the dash) connected, this will make the solenoid pulse rapidly letting you spray brake cleaner through it. if this doesnt solve it, you may need a new solenoid (i have a spare 2 port available for a tenner if you need one)
i had exactly the same problem when i first got my classic, it was the exhaust causing boost to build too rapidly, i tried everything (new solenoid, pipes etc) in the end i drilled the pill out slightly (to 1.5mm from 1.2) and it holds boost perfect now.
if yours is remapped then be a bit careful as they have likely leaned out the standard map and advanced the timing to get more power so you could be running very lean if you are overboosting

samtothed

Hi thanks for your reply.

I will blast out the solenoid and hoses with brake cleaner tomorrow afternoon and see if that cures it. From speaking to the previous owner there is a chance that the exhaust MAY have been fitted after the remap. Hard to know for sure as I am the 11th owner!!!

If I do have to modify the pill, could I not fit an inline bleed valve and adjust it until I am back to 14 psi or so? What does yours boost to?

Ps, the boost pressure I am reading is direct from the ECU map sensor.

tjmatt

iTrader: (1)

AFAIK the MY99 boost control is reasonable and normally copes ok with a decat downpipe. One thing to check is that its all plumbed in correctly, restrictor pill in the correct place (immediately after turbo outlet nipple - this is not the same setup as early classics)

As a side note, are you sure your car has been remapped? You boost cut is the same 1.2 bar that the standard ECU has, which should have been upped with a remap because they tend to run about 1.3 bar midrange with a remap. I would say its likely someone has had a manual boost controller on before and either changed the waste gate pre-load or cocked up the plumbing putting it back.

The waste gate lever is adjustable and people suggest that the pre-load is enough such that you can see half a hole through the rod's hole when pulled off the waste gate arm with the wastegate shut. Hard to explain and better explained elsewhere. If the pre-load is too far too high then its possible to cause overboost. The alternative to this is to open the hole in the restrictor as mentioned above, which has a similar effect.

To check the wastegate works correctly, and adjusted well, you can connect the turbo outlet nipple direct to the actuator (without the bleed tee) and this should net you about 0.5bar or 7 psi of boost. If it still boosts the same or is much above this that would suggest its not working or poorly adjusted. If that is fine then perhaps the exhaust really is too free flowing in which case it should be properly mapped (sounds like it hasn't been) or the Decat removed. Is it worth noting that if the boost solenoid is partially blocked this will reduce boost, not increase it. So cleaning or replacing won't help.

samtothed

Hi, the pill looks to be in the right place, after the turbo and before the T piece.

What is interesting is that on the inlet manifold there is a cut silicone vac hose on the spare nipple, bent over and zip tied to seal it. What's more interesting is that the PSI3 data monitor was set to read boost pressure from an external pressure sensor when I got the car. Could this have been for a boost controller.

As for the remap, all I have is a dyno print out from Engine Advantages in early October 2005, in the rest of the bundle of history is a receipt to supply and fit the xtreme downpipe dated mid October 2005. Hmm. Previous owner says that he has never added or replaced anything and that he never really pushed the car too hard, which could be believable.

If the pipes with the pill were oiled up then would this cause overboost? As this would have the effect of making the hole smaller? Could I run a cheap boost control valve around that area to do the job of essentially making the pill hole bigger?

Thanks!

tjmatt

iTrader: (1)

Definitely sounds to me like its not been remapped then which is a shame because its not cheap! Almost all the MY99 cars show about 235 to 240hp on the dyno with a simple Back box change. Sadly remaps for these aren't cheap but is the best way to solve it. Next best is either enlarge the hole (or as you say try cleaning any oil out of the pill), or slacken the wastegate arm off a touch (but make sure it can still shut) in order to give the boost control a fighting chance. It is semi-closed loop boost control so you don't want a massive hole or you may just find it works for spooling then you have low boost elsewhere - the problem is mostly because the turbo now spools faster. But it sounds to me like you've worked out how the boost control system works so yes you can plumb in a manual boost controller with it set to 0.9 bar if you have no luck with the ECU controlled one, but don't be tempted to turn it up if you don't remap

Tbh I'm suprised the ECU can't control it, I never had a problem in the past with Decat and Back box change. I would see what boost you get without the 'T' and connected directly, knowing that this shouldn't be more than 7 psi gives you an idea how well adjusted the wastegate is in the first place. At least that is an easy test before having to remove the heat shield to get to the rod adjustment.

samtothed

Hmm yes, I am also now doubting the remap. I just can't see that this could have been driven like this since 2005 and now at 114000 miles surely it would have popped by now!

Job list then:

1) Blast out vac pipes and pill with brake cleaner. See if that works.
2) See if I'm boosting above ~7psi with turbo connected directly to actuator.
3) If no change, buy a £10 MBC and adjust the boost DOWN to ~14 psi. Where exactly should this be plumbed between?

A £1500 car is not worth a £500+vat remap!

Thanks for your help so far. I will report back tomorrow afternoon with the outcome! Fingers crossed that the pipes are mucky or the wastegate is sticking or for anything else simple!

This is my first Impreza, first Jap car for that matter, that I fully bought on a whim. At least the turbo is on top of the engine, I'm a BMW man 5 days a week and replacing the turbo on my diesel was a nightmare on my back!

BILLETBEANZ

iTrader: (1)

I get overboost on mine in this coldweather on motorway but thanks to closed loop thing.. it ok for it to overboost..

johnwiz

iTrader: (26)

Just a suggestion,once you have your basic turbo plumbing sorted you could buy a second-hand Apexi power FC ECU (Around £300).There are many good mappers for this ECU & at least you can remove it if you sell the car & get your money back,unlike an Ecutek'd remapped ECU.
This is the route I'm going with my MY99.Cheers,John

keljon

iTrader: (10)

problem with a power FC is you lose some of the built in safety features of the standard ECU, a used ECU with ECUtek license goes for around £150 on here, mapping costs around £300 so its actually cheaper to go this route than an Apexi Power FC.

A better solution is to go for a simtek and get rid of the MAF but this is expensive and overkill unless you plan on going for 350+ IMHO

keljon

iTrader: (10)

sorry should have said, point 2 was one of the first things i did to check the actuator was ok (which it was)
problem with a MBC is you will lose some of the ECU ability to control the boost and it will need adjustment when its colder for example or you will overboost, best to get the factory boost control working properly then get it remapped if you want more power

samtothed

Ok, I did some investigations this afternoon. On the way I stopped at the local Subaru specialist that the previous owner used to ask about the problem. He seemed to think that either the BCS needed cleaning or the wrong sized pill, or just that it was very cold at the moment.

Anyway, I got on with it...

First thing I noticed was a small split on the vac line at the turbo nipple.



I took it off, chopped off the end and re-attached. Went for a drive with high hopes, but still boosting to 17.3 psi!

Ok, next I though I'd flush out the vac lines, the pill, and the solenoid with brake cleaner. Just to see if that would have an effect. I also got a chance to inspect the pill.



Difficult to tell the size as its deep in the pipe (I'm suprised the iphone managed to get a snap of that!) but it doesn't look quite 1.5mm, could indeed be a 1.2mm.

I blasted out all the turbo related vac hoses until the juices ran clear.



I put the greeen and black test connectors together and flushed out the fast-clicking solenoid with plenty of cleaner. Unplugging those connectors under the dash is mission impossible, I ended up reclining the seat and lying upside down with my head under the dash to unplug them, what a scene.

I went out for a drive, with high hopes again.



17.3 psi again! So yes that didn't have an effect as guessed.

Next, I found a straight connector (from a windscreen washer pipe I think) and joined the turbo to wastegate pipe without the BCS.



Took the car out again and....



7.3psi! A bit more of a result. So the wastegate is deffo working correctly.

So, the fix looks to be to increase the dia. of that pill. Thing is, I don't really want to as if I drill it slightly to much then there is no going back, and the boost will likely change once its warmer. So I've ordered a MBC which I'll use to turn the boost DOWN and leave it set. I figure if I set it up in the cold dense air, then it won't get any worse once the weather starts to warm up.

Hopefully I'll have the MBC tomorrow, so I'll report back then! Thanks for all your help so far.

samtothed

Issue resolved.

Fitted the manual boost controller in place of the boost control solenoid using all the standard hoses and fittings.

Used about an 8th of a tank setting it up mind. Now locked off to 14.3 psi. That'll do pig. Much better to drive now, can actually rev it without keep hitting fuel cut.

What's the standard boost supposed to be? A round about 14 seems reasonable to me.

keljon

iTrader: (10)

0.9 bar and standard pill is 1.2mm, drilled mine to 1.5mm and now holds boost perfect