john banks

If the MAP sensor was artificially under-reading boost by 1-2 PSI would the held boost go up by the same amount? Means of achieving this could be a valve (bleed or restrictor) in the supply line or a voltage adjustor (but not a clamp as I still want a cut out if it goes mad).

Does the std/PPP ECU use the MAP sensor to control the held boost? (which seems to be independent of wastegate restrictor size unlike the peak).

Is the MAP sensor data used for anything else other than boost cut out? Does it have any effect on fuelling or is it all done by the MAF?

If the fueling/knocking was monitored could this be safe?

How much boost is safe for 100000+ miles on a UK engine with standard internals/intercooler/turbo? How about 18PSI peak/held? I know some of the Superchips guys run more than this. My PPP is holding just under 17PSI according to my gauge. At an indicated 18PSI peak the boost flaps up and down and I presume this is the ECU complaining.

Is my 17ish PSI about as far as is safe for a UK engine then? Is there any way to access the very top areas of the ECU mapping?

(Should've bought a Link I know).

Sam Elassar

john
i have my car running at 1.3 bar for the past 20k miles with no problems, you can even run more if you are brave enough. but you need and ECU for that though it get the full benefit.

and YES you should have bought LINK

sam

john banks

Thanks Sam. So that's about 19PSI - held I presume. What peaks are you getting?

On the Select Monitor, the car was wavering boost around when the boost went to 1000mmHg = just over 19PSI = 1.3 bar. Why then does my car seem to do it when the boost is only hitting 18PSI - could it be my gauge underreading compared with the MAP sensor? Is the gauge likely to read differently if I use the spare nipple on the manifold rather than current T-piece into the line supplying the MAP sensor - line is too short to reach so far unless I get some longer tubing. I am wondering if the restrictions in the line drop the pressure so the gauge is reading artificially low.

Presumably the mapping goes up to 1000mmHg/19PSI, so I am wondering how I could get say peak/held as near to this as possible.

For those running boost controllers with std or PPP ECU - how high do you let the boost go and why? Where does the ECU start to moan - presumably with boost controller you retain the ECU's overboost cut out?

Also thinking about Dawes Devices kit which uses a relief valve which keeps the wastegate completely close until target boost is reached, like a manual boost controller. But I gather this removes boost control from the ECU - also the wastegate solenoid pulsation stuff? How smooth is a Dawes car to drive?

[Edited by john banks - 10/17/2001 9:59:59 PM]

Sam Elassar

hi john
i was peaking to 20psi and some times at very high revs to 21psi but very only lasting for a second or two. overboosting is nothing i would really worry about unless you are overboosting by 4-5psi.

couple of things to keep in mind though
1- how accurate is your gauge ? i usually use the link tuning module and that reads striaght of the map sensor. what i ususally find is my gauge under reads a little bit by one or two psi usually.
2- the fluctation you are getting with the boost could be due to the ecu ? or due to the gauge adding a restrictor inline with the gauge will help. i get fluctations with the link if i did map the boost properly for example.

what gauge are you using ?

scoobs

Hi guys, Sorry to hijack the thread a bit but:

Does that mean I can run 1.3 or more Bar on my UK MY00 Turbo??
I have an EVC IV and Unichip. Currently running 1.2
I thought 1.2 was all the internals were good for, any more and you would have a melt down.

Thanks

Scoobs

DARREN

My STi is peaking at 15 psi,could i fit a bleed valve and adjust this to 18 psi and be safe????????????


Darren

WREXY

Hi Peeps,

My mods include,
APS induction kit,
5 Zigen canonball exhaust mid and backbox (catless mid)
Blitz DSBC boost controller.
Standard ECU
SUL 98 RON
Blitz BOV (irrelevant to performance)
Blitz dual timer (irrelevant to performance)

I have the Blitz DSBC controller and I remember the standard ECU cutting the engine out at around just under 1.3 bar, actually it's not bar, but kg/cm2 (hitting overboost). I raised the boost to see where the cutout was.

I run around 1.2 Kg/cm2 on my MY00 to be safe. Well I think it's safe. That's overboost and it falls to around 1.19 held. When it is a colder day it can creep up to 1.25kg/cm2. On very hot days, which is all of summer here, I drop it down to 1.1 / 1.15kg/cm2 manually, coz I'm a little scared in case the engine pops. We have 40deg Celsius days here almost every day for summer. I run 98 RON SUL. I'll be finally fitting the Knocklink tomorrow to see what's going on.

Cheers,

Wrexy

[Edited by WREXY - 10/18/2001 12:47:54 AM]

the hooded claw

Sorry guys but how and where do you fit the bleed valve.I know to on an rs turbo but these boxer engines are new to me. Please help.

dmel

This will answer your question my friend:
http://www.scoobmania.freeserve.co.uk/my_impreza_mods_boostinc.html

Sam Elassar

i really don't know where did the 1.2 figures came from ? i don't remember anyone actually testing the standard internals. if the are modded properly you should not have any porblems really.

one thing to bear in mind your engine is not going to last as much running 1.2 bar as it will running 1 bar, and the same applies to running 1.3 or even 1.4 bar on the standard interanls.

i think the earlier cars had smaller injectors 380cc and therefpre going over 1.2 bar was not recommended, the MY99 onwards can cope with 1.4bar with out needing to uprate the injectors


obviously i am not held resoposible for nothing here, just my own experience

john banks

The boost on mine fluctuates only when the restrictor is too small. I presume the MAP sensor must be reading 1000mmHg at this stage hence the fluctuations. Certainly I only got this behaviour on the Select Monitor if the boost hit 1000mmHg. Having the boost gauge on or not makes no difference. So maybe my (cheapo Falkland £40) gauge IS underreading and a reading of 18PSI is actually 19PSI. Might put the voltmeter back on the MAP sensor to check. At the moment I run the peak boost so it is within 1PSI of the point where it would fluctuate. So I could therefore be over 18PSI peak and 17PSI held (around 1.2bar). If that is the case, I think I am comfortably as near as possible using most of the PPP's map, so I'll leave it like that. Would be nice to be able to get reliably to 19PSI and hold it though with no spikes, but even with a boost controller this would seem unlikely as they can only regulate it to 0.5PSI apparently, so it would appear that adding a boost controller would only get me up to 1 further PSI unless I fooled the MAP sensor, which I'm not keen on.

Sam Elassar

hi john
i did not mean that the gauge would have caused the fluctations (poor english), i meant that you can also see fluctations if the gauge is off poor quality. i know someone who had to put a little brace restrictor in the tube just behind the gauge to get rid of it. it was an autometer gauge.

sam

john banks

OK Sam. Get you now! But a gauge if poorly installed with a leaking T-piece in the MAP line could affect things, which is what I thought you were thinking. However, there are no boost fluctuations when the boost is running properly - it is only if it peaks too high and then you can also feel it/hear it in the exhaust note, so I don't think the gauge is susceptible to fluctuations.

Have tried some more voltage readings off the MAP sensor, and it seems to confirm what I thought. When the boost gauge is reading about 18PSI and the boost is then pulled back the MAP sensor is giving 4.1-4.2V. based on 0.88 = -1bar and 4.84 = +1.8bar I reckon this is just over 19PSI (1.3bar, approx 1000mmHg). Or at least according to the MAP sensor. Of course there are errors in these things, but obviously the ECU thinks it's reached 1000mmHg and hence it backs off the boost.

I think in practice once I get an adjustable restrictor I just move it until I get fluctuations and then turn it back a little until I don't = max extractable boost So then I'm running 1PSI more than I thought! = 18.5 peak 17.5 held.

[Edited by john banks - 10/18/2001 5:42:12 PM]

RaymondH

The 1.2 bar comes from the standard ECU fuelling to 1.2/1.25 bar - any more and it can't cope. Or so I'm told. I run my EBC at 1.15 with an extra 0.05 () for overtaking.

Raymond.

AJbaseBloke

Why not try earthing the engine?

I get on boost with little fluctuation very smartly - no big overshoot anymore, and things feel a whole lot more together now.

Just an off the wall idea (thousands of Scooby owners are doing it here).

GavinP

John,

Using the Dawes MBC on my car does not result in any fluctuation in boost levels - the boost curve is considerably steeper because of keeping the wastegate shut, as you said.

The only issues of spiking I have heard of is where people have used lots of tubing to connect the MBC - rather than keeping it as short as possible. Doing a search on http://www.i-club.com is a good indicator - it is widely used.

In colder weather, the boost does creep by 0.5psi max so not a big issue.

I am toying with the idea of setting the MBC to 6psi and then reverting the boost setup back to stock apart from the solenoid to wastegate line. This would allow the ECU to control boost but would keep the wastegate shut until the solenoid opens it.

Thanks

Gavin

john banks

Gavin, I am starting to get quite interested in the Dawes Devices MBC as I outlined in another thread. Your experiences in more detail would be useful, and I am also searching I-club.

motomc1

HI anyone.when my 98my is at idle.if you rev it slightly you get a ticking sound from a relay thing under the right side of the bonet.what is this and is it a problem.didnt do it when i got it dose now .????????????thanks all

John Stevenson

Sounds like the wastegate soleniod.

GavinP

John,

OK, experiences so far....

94 WRX Automatic - 12psi boost standard. Replaced exhaust and air filter and then decided to up the boost a little.

Increased boost to 14psi using a Turbosmart boost controller which was basically a bleed valve with a little air filter on it.

Connected it between the wastegate and turbo "nipple" and connected remaining hoses together with OE hose joiner (as per supplied instructions). Looks just like FCD 1 on Turbosmart's site: http://www.turbosmart.com.au/fcd_aus.html

Raised boost with no problems but creep was about 2psi with atmospheric extremes which meant that to keep under the fuel cut at 15.5psi (on early cars), meant running at 14psi day to day.

Removed the bleed valve when Bob fitted and mapped the Link ECU. Boost control was tricky during mapping due to kickdown - this would result in extreme overboost. Bob managed to fix this by changing one of the restrictors to produce a far nicer running car at the end of 7 hours hard work. Bit faster too.. Top job.

After a while I began to toy with the idea of changing the turbo as "lag" was still apparent (although reduced significantly by the Link map). I then saw the Dawes web page, ordered a couple (one for a mate with a manual 94 WRX) and fitted them when they arrived a couple of weeks later.

As stated previously, this has increased the "steepness" of the boost curve by a huge amount. Being strictly accurate, lag hasn't been reduced as this is a limitation of the turbo used but the "feel" is that it has - the needle on the boost gauge absolutely flies round...

When you first fit it, the boost seems "violent" as it builds so quickly (my mate managed to spin his wheels! - I guess the slush box on my car tamed it somewhat) but after a couple of days you adapt your driving style and the car is MUCH quicker point to point than it was before... I would not go back to a stock setup now!

I notice that Turbosmart no longer sell the boost controller type I had and have some new models that may be worth a look: http://www.turbosmart.com.au/boostcont_aus.html

However, the Dawes MBC is a serious bargain - it's just a bit of a pain having to create a PayPal account to pay for it. Took about 2 weeks to arrive from ordering on-line. Quality is good and the results are seriously impressive IMHO .

I don't know how much of a factor the turbo type is (TD05H models are notoriously laggy) but as it keeps the wastegate closed for longer, I would expect to see benefits with other turbos.

If I were in your situation, I would leave the MAP sensor alone. Feeding the map sensor duff information seems a very bad idea IMHO.
Bleeding boost away from the MAP sensor will cause the ECU to run with inaccurate information whenever you are on boost.

I ordered a FCD Type 1 from Turbosmart with the boost valve but decided after on-line discussions to never use it. If you want higher boost, then a Link ECU is a "proper" solution. Not cheap admittedly but you can remove/re-sell it if you change cars and far less expensive than an engine rebuild.....

I don't think you will be disappointed with the Dawes MBC...

Let us know what you think!

Thanks

Gavin

T-uk

saw in a advert that Carnoisseur do a "in-car adjustable boost control kit" for £40.

john

dmel

Ajsbloke,
what do you mean with "earhing the engine" ?

AJbaseBloke

Earthing has been a bit of a hot topic on Legacies, but WRX owners have been doing it heaps too. Lot's of kits available in Japan, also pretty simple to DIY it. It basically revolves around taking lines off the manifold etc back to the minus terminal. Upgrading the body to minus terminal cable also seems to help. The idea being to help the sensors get as pure a reading as possible.

A nice side effect is that it can help the stereo sound better too!

Take a look at this site, look under DIY:
http://www.lumine.net/subaru/legacyb4/index.html

Hope this helps.

Cheers.

Luke

Tried the "Earthing mod" about a 6. Months ago. Yes the stereo does sound better. It also picks up a bit better.
For what It costs to do £30.00 tops. And about 2.hours it is well worth it.

AJbaseBloke

2 hours?? Luke, you must have done a VERY thorough job - my 5 point version took roughly 20 minutes (and looks it ) - other guys who did 7/8 connects took about 35 to 45 minutes.

But giving yourself plenty of time is not a bad idea.

Good luck with this one - it works, is cheap and as long as you remember to disconnect the battery and cover the plus terminal when doing the job (don't laugh, a bloke - not one of our mob thankfully - did not here and got his fleece well lit up!) should be a safe one.

Cheers.

Scott.T

iTrader: (2)

Just been on the Dawes MBC site http://www.dawes.com after reading the above and would be interested in more views on this device.

I currently have a Bleed Valve fitted and am running 14psi (Held) boost, but do suffer from fluctuations in Boost and higher peaking boost.

I guess that the Dawes MBC will sort this ?

Luke

AJbaseBloke

!!!!!! It looks LOOOOOOOVley. Monster Red cable ,with full soldered ends .Crimped and shrink wrapped. With "BANZI" (Sounds good !!) Customed made battery bracket. At the last MOT about 4 Inspectors had a right laugh when they saw it !!! Even got "Subaru" stamped Cable ties

God knows what the neighbours thought !!

GavinP

Scott,

Yes it would - with your bleed valve setup you are keeping the hoses as short as possible, aren't you ? This generally is the cause for overboost.

Either way, this is superior to any bleed valve due to the method of operation - just be careful when you first fit it not to break traction. Boost builds very quickly...

Thanks

Gavin

Scott.T

iTrader: (2)

Gavin,

Just tried to order one, but the payment method only seems set up for US addresses. How did you manage it ?

Don't worry.....sorted it.

[Edited by Scott.T - 10/22/2001 10:37:01 PM]