legacy owners...help!!!!!!!

well just need some info...i have a 98 legacy RS...twin turbo...when i come to 4000rpm i think thats when it changes onto the second turbo
on mine the boost just falls off a bit and once its passed 4000rpm it starts to pick up boost again..
now since iv never had one of these before or even been in another legacy iam wondering does this happen in others or has mine got a problem...
the car is lovely but this really lets it down to drop off boost when goin up in the gears...

please help with any info ,or if anyone might know what may cause this..

thanks gizmo

Is this not the VOD (Valley of death)

It should only drop 0.2 or 0.3 bar before shooting up to full boost.. Is it just slow reaching full boost on the second turbo? Mine has this problem at the moment and i was told by dave and bob rawle thats its 1 of 2 things.. either the switchover valve is sticking a bit and restricting the exhaust gas or its the *actuator valve* on the turbo thats struggling to open. Either way its a case of carb cleaner and loosen up the joints..

**'s mean i dont actually know what the valve is called so i took a guess :lol:

Dump valve dumping all the boost :S

i did a google on the switchover valve thing...anyone understand any of this post below..

..........................................................................
Short answer: It is a combination of electrical and mechanical processes that allow transition from one turbo to both turbos. True sequential turbo setups are *NOT* solely limited to a simple mechanical operation or difference in turbo or turbo housing sizings... in most cases the car's ECU is heavily involved in the process.

This is the same idea but not necessarily same *implementation* used in Porsche 911 Turbos, Supra Turbos, Skyline GT-Rs, and Mazda RX-7s.

Long answer:

In my other car this is how it works (not my words, but leaving credit out merely for my other car's anonymity):

.....first off, [there] is no #2 wastegate. there is only one wastegate and it comes off #1 turbo because that turbo is always on line, therefore you always have a wastegate. there are 4 sets vsv's, actuators, and control valves for the sequential turbo system. each vsv is simply a solenoid that is either 100% open or closed, allowing manifold pressure to pressurize the different actuators that open/close the four different valves.
wastegate: when the manifold reaches 11#'s of boost, the ecu sends a signal to the wastegate vsv, this allows manifold pressure to build in the wastegate actuator which opens the wastegate.

exhaust gas bypass valve: somewhere around 3500 rpm, the ecu sends a signal to the exhaust gas bypass valve vsv, which allows manifold pressure to build in the exhaust gas bypass valve actuator which opens the bypass valve. this is a small opening inside the #2 turbine housing which allows some exhaust gas to go through the turbine of the #2 turbo which makes it start spinning, and dumps the exhaust gas out the exhaust piping coming off of #1 turbo. since it is a small amount of exhaust gas, it pre-spools the turbo and does not get it up to full operating speeds. this will smooth out the transition from 1 to 2 turbos. this valve is similar to a wastegate in design, but is located after the turbine wheel instead of in front of the turbine wheel like a wastegate would be. this is not a wastegate!

exhaust gas control valve: this valve is located in the exhaust piping downstream of the #2 turbo. when this valve is closed, all exhaust gas must go through the #1 turbine wheel to get out through the rest of the exhaust system. at around 4000 rpm, the ecu sends a signal to the exhaust gas control valve vsv, which allows manifold pressure to build in the exhaust gas control valve actuator which opens the control valve. this allows exhaust gas to go through #2 turbo and out the exhaust system which brings the #2 turbo up to full operating speed.

intake air control valve: this valve is located in the intake tract coming off of #2 turbo. it is closed below 4000 rpm so that boost pressure coming off of #1 turbo cannot backup through the #2 turbo and back out the air cleaner/suction of #1 turbo. there is also a 1 way reed valve within the same housing of the intake air control valve. as the #2 turbo starts to prespin at 3500 rpm, it will build some boost. if it builds enough boost, it will open the 1 way reed valve to allow this boost into the intake tract to join with the discharge boost pressure coming off of #1 turbo. at somewhere over 4000 rpm, the ecu sends a signal to the intake air control valve vsv, which allows manifold pressure to build in the intake air control valve actuator which opens the control valve. this allows the full boost pressure coming off #2 turbo to join in with that coming from #1 turbo and you are now fully on line. usually, the exhaust gas control valve will open first, which gets the #2 turbo spinning at full rate so that it is building good boost before the intake air control valve opens, allowing this boost to join in with that coming off #1 turbo.....

[quote author=briancollins link=topic=8805.msg104711#msg104711 date=1218314113]
Is this not the VOD (Valley of death)
[/quote]


ya brian i seen something about that vod thing on a google too....the whole thing might wait for a vod if it cant be sorted..ha ha

All twin turbo Legacy's have a VOD. Some cars VOD will be more noticable than others, a dump valve is said to make the VOD more noticeable. Have you got the car mapped? If you havent, you should, it will make the car run better and safer. Also the mapper can tighten the changeover from primary to secondary turbo making the VOD alot less noticeable.
Once your used to the car your driving style will change abit to account for the VOD, it will never fully dissappear though - unless you do a single turbo conversion!!

It's a wastse of time mapping it, if there is a problem with the change-over between the primary and secondary turbo. Get the problem repaired first, and then you can map it. I have repaired many of these, and even with a vent to atmosphere dump valve, there not too bad. Any gunk in the pipes, or soleniod's, or an air leak will cause the VOD get a lot worse. The system is charged with vacum just after starting, and this is stored in the vacum tank. There are 2 change-over valves, one for boost, under the intercooler, and another in the exhaust for the gasses feeding the primary and secondary. They need to change over at exactly the same time.

John

You won't be able to map it on the standard ecu ecutek won't work on pre BE legacy's..you could use a HKS f con..but I think the only people in ireland who map these are TDP..i got a qoute of 1800 euro 18 months ago.

[quote author=johnny99 link=topic=8805.msg104881#msg104881 date=1218443305]
It's a wastse of time mapping it, if there is a problem with the change-over between the primary and secondary turbo. Get the problem repaired first, and then you can map it. I have repaired many of these, and even with a vent to atmosphere dump valve, there not too bad. Any gunk in the pipes, or soleniod's, or an air leak will cause the VOD get a lot worse. The system is charged with vacum just after starting, and this is stored in the vacum tank. There are 2 change-over valves, one for boost, under the intercooler, and another in the exhaust for the gasses feeding the primary and secondary. They need to change over at exactly the same time.

John
[/quote]
is there anyway of testing for this defect, ie leaky pipes or blocked solioids. as far as i know my car is runnin smooth but i dont have anything to compare it with other then the other b4s i test drove months ago. is checking and cleaning out the solinoids a big/exspensive job, could i do this myself????

I'm havin similiar problem, engine check lamp is on constant, drives smooth when not puttin the foot down, but give it some power and once it hits 4000 revs, bang, timing retards or something, total loss of power, someone has had it now the last 3 weeks and gettin no where. If I get anywhere I'll keep you posted.

Jayotala I get that now and again - seems to happen whenever I get petrol in certain places, maybe dirt in their tanks or something.

I usually just reset the ecu and it goes away - Go under the steering column and connect the two black connectors & the two green connectors (With engine off) start up and drive for a bit - the check engine light will flash on & off constantly, turn off the engine, disconnect the cables and see how you go. Oh yeah -dont do that if you've had it remapped cause it'll undo all the changes (puts the ecu back to factory default).

As for the lag between boosts they all do that - turbo 1 is 2,500rpm -4,000rpm turbo 2 doesnt kick in until 4,500rpm.

If you wanna reste the ecu from safe mode just disconnect the battery for a couple of minutes..no need to take it to factory settings

D'oh and I've been doing the full reset... any idea if that causes any bad side-effects?

I wouldn't think so, same thing really..its probably just akin to plugging the plug out on your pc when all you have to do is restart it from windows....be more concerned if my car was going into safe mode in the first place..especially now with e5 available

On that note - I'm nowhere near any stations that do E5 but there are 2 nearby that do E85.

Was thinking - is it safe enough to put say 35ltrs reg 95 + 15 ltrs E85 -My mathematical skills are rubbish but I was working that out to be total of 4.5% ethanol - if E5 is 5% i presume the 4.5% with that mix would be the same?

With that mix I'd be up to averae 97.7 RON + adding Proboost bring it up to 99?

Seems like it'd be safe to me but half afraid to chance it. Any thoughts?

piss would have a higher octane rating than Proboost muck, but might look a bit weird Peeing in your tank at the local garage!

Most garages by now in Leinster are selling e5 but only Maxol have it advertised as being 99 ron. might be safer to get a remap to 95 + booster for your situation

Hm, my mathematics says that 15l of E85 on top of 35l Pb95 will give you over 25% of ethanol, which might be a bit much...
Myself I would put rather something like max 10l of E85 to that mix.

Anyway the best idea is to find the nearest Maxol station and buy E5 and in addition if you like put another 5l of E85, or maybe better if you don't feel sure, some Octane Booster on top of it.

And another thing is - I found that most people find ProBoost rather useless. Many tests shows anyway that Lucas, NF, NOS are much more efficient and the only worth of using. But your choice of course.

Cheers
Jacek

Cheers, Hahah knew my math skills were poor!

Nearest E5 station is about 50 miles from me so not worth the trip. Have to say I noticed no difference with proboost alright.Do you know is miller's any good, can get that locally.Otherwise tis off to t'internet for something better.

Thanks.

Where do you get E85 from then? Is it maybe one of those literally three Emo stations?

Anyway if you have e85 near, you can mix those few liters with regular petrol.

You can try Miller's as well I think - I forgot to mention this one, which some people say is not too bad, too.
Anyway be careful, as they also make some booster with lead addition, which will simply be no good for your cat.

cheers