UHF

I just went out for a spin with my newly fitted scoobysport back box and the car is not pulling anywhere near as well in 4th and 5th, its almost as if its over boosting and the ecu is cutting back, accelerating up through the top end of 4th is weird, you kinda go and then it stops pulling, then you go again, rather weird, it does it on the top end of 5th too (i know I was being naughty but I could only test at high speed).

Its like the feeling when you hit a wall of wind coming at you all of a sudden but like every 2 seconds, i'm a bit worried to say the least, all i've done is changed the back box! Its a MY99 Turbo with ITG and ss back box.

I'm due for a full decat on friday, should I get this checked first? help, i'm scared now!!!

I remember the thing pulling all the way to 130-140 and then trailing off after that but this is nowhere near as good.

Also 2nd and 3rd feel like the power curve is lower down, the turbo spins up lots and makes lots of sucking noises around 2,500 now instead of 3,000 like when it was standard, it just seems that my power curve just headed south by about 500rpm at the bottom and 1000rpm at the top.

Is this natural?

nom

Some of it... My guess is your boost is waving about as the ECU is no longer predicting correctly where it's going to peak, to it overshoots, overadjusts, etc. Normal, and is much more pronounced with the DP, especially in cold weather. This is where the Dawes can come to the rescue!
The fluctuating boost can reduce power at times obviously (when it undershoots) but there is a potential for the DP (and I suppose to a point the BB) that the car can feel slower as the boost is so much more progressive. It is, though, quicker. Can be quite a bit quicker

UHF

really, didnt think a back box would make that much difference.

I keep hearing about these dawes things and knocklink but havent a clue what you guys are on about! got some links to some nfos?

UHF

I just wanted to make sure the car was ok, its taken me ages to pluck up the courage to blow away my warranty! and now i have i'm going to be paranoid about everything.

UHF

I think i'll be getting myself a boost gauge next, wanna keep an eye on this stuff!

Scooby Bloo

Can't search from my home computer, but will post some links for the Dawes Device tomorrow.

Basically it's a manual boost controller, which obviously increases the boost, but, theres always a but you need a boost gauge to set psi also a Dawes AFR meter would be handy

This tells you whether the cars Air/Fuel ratio is OK as you don't want the car to run lean when upping the boost.

Cost= Dawes Device £50 = 15%-20% bhp increase
Dawes AFR meter £65
Boost gauge £30 - £130?

Cheap mods for the extra horses.

Me running 16 psi or 1.1bar there abouts, decat centre, Scorpion bb, jr filter All safety gadgets rolling roaded at 260 BHP


Steve

UHF

all I want is a decat system though, do I really need to spend all this extra? I dont want to up the boost (yet anyway)

So whats the list of saefty gadgets I should have, I'll have to buy them next month it seems!

stevied2

One of the first safety devices I would and did get, was a new oil pressure switch. The original one is set either 5 or 8 psi.

If your oil warning light comes on while driving, at that psi the engine would be toasted you can get upgraded to 35 psi, (much safer) for around £35 and its a direct replacement, so it's easy to fit.

I opted for the SPA dual oil pressure/temp gauge. you can set your own safety limits on these gauges, marvelous things IMHO.look here

Then went for Boost gauge, followed by AFR meter and then the Dawes Device and upgraded air filter.

you can then add fun bits like VTA dump valves and things

UHF

do those gauges pick up info from the ecu or do you have to run wires and stuff? I like those ones where you connect them to the ecu and then run all the gauges from a control box, bucks tho!

stevied2

No, the gauges have replacement sensors, its just a case of unscrew one sensor, replace with new one which has a plug already wired up.

Fit the gauge, connect the plug to the back of the gauge, run the wires through the bulk head, I found it easier to go through the passenger side as there a huge rubber grommet to feed them through.

Connect to power source ie. cigar lighter

Then connect wires to sensors, no need to mess with ECU at all.

I fitted mine easily, and I'm no genius.

If you do want to fit one and need help where to fit sensors and such, or talk you through it, mail me on my profile address and I will give you my phone No.

Steve

UHF

dont you need to keep the built in sensors on the car for the ECU to read stuff? also I want to keep my existing dash stuff working.

Is this just a money consideration, i'd very much like not to replace existing sensors if the ECU needs them

stevied2

The car doesn't have an oil temp sensor fitted, this is screwed in a hex nut on the top of the block, under the throttle body so you don't have any dash lights for this anyway.

If you do a direct replacement on the pressure switch, you will loose the oil warning light on the dash, but in my opinion it's better on the gauge coz it flashes red when you drop under your set pressure, whereas you only see the light on the dash when you initially start the car.

As I said above, if the dash warning light, lights while driving your engines already toasted

If you still wanted the warning light on the dash, you can always use another place for the gauge sensor, as there are enough mounting places.

P.S. I hope I'm not giving the immpression of being cocky, as this is not the intention.

UHF

no no, sounds like you're obcessed with oil temp tho which is reasonable, i first want to find out what my boost is tho.

I didnt expect to have all of this, i dont want to increase boost, I just want the advantages of a full decat, I dont really want to go any further, do I still need to go to these lengths?

UHF

MY99 turbo UK, i see your issue with the oil, I keep regular checks on the oil anyway. But i see your point.

I think my first purchase after the decat should be a boost gauge to monitor the overboost situation! and then once i know whats happening purchase something to fix it, but seriously all I wanna do is decat and run car, i dont want to start playing with boost etc.

ozzy

UHF,

Get yourself a boost gauge and a Knock detector (either the ugly original Knocklink, the mucho expensive cool new one or Scoobymania's own version). Make sure you get the seperate Bosch sensor too as this is much more accurate than the OEM one.

That's exactly what I'm doing.

It's detonation (aka knocking, pinking or just det for short) that'll wreck your engine.

Stefan

stevied2

You should try it, it makes quite a difference. The Dawes thingies are a cheap mod, and are safe.

But happy decatting

UHF

yes but my point all along is that why should I be getting detonation just becuase i'm decatting it, i would usually associate detonation with wrong mixture, ala turning boost up without sufficient fuel which is not what i'm doing, i'll get the knock link and boost gauge and see how it goes.

Nigeyboy

UHF

couple of points (I am in no way technical)

Have you spoken to SS about this. Maybe they have a view on what the BB should do in terms of response. Apparantly they have worked with Janspeed to optimise design etc. - according to their website.

I have heard that a full decat requires an engine remap as the timing etc of fuel/air and turbo pressure is out and results in overheating and eventually piston meltdown. I tried to get a thread going on this the other day, as I would like a new BB and maybe a centre decat on a MY02 WRX.

See, told you I wasn't technical.

Hope the mods go well

NB

UHF

Its a second hand back box, i'm getting the DP and CS from them tho on Friday, i'll ask them.

stevied2

Iv'e been running with decat centre and Scorpion b/b for quite a while now, with no problems.(touch wood). Car has not been re mapped or anything, does not run lean, according to afr meter.

UHF

well thanks guys, i'll consider everything, its been very informative reading your replies, damn I love this board, subaru drivers are some of the nicest people about

ozzy

UHF,

Even on my totally standard MY99 I had a couple of degrees of Knock correction show up when John Banks used DeltaDash on my car.

The simple point is you have no idea if it's doing it or not and (more to the point) how bad it is when it does occur.

You are supposed to hear the pinking noise when it's bad, but you'd need the hearing of a bat for the majority of cars.

Stefan

ozzy

I'm so sweet and nice, my f@rts smell of buttercups

Stefan

UHF

so does the knocklink just report or adjust things? i mean if its telling you that theres a problem then you gotta get it fixed still right or will it fix it for you through adjustments to fuelling? i dunno!

watch it ozzy!

ozzy

LOL

The detectors simply listen for knock (using a seperate, more accurate mic) and display the severity as a row of coloured LED's. The further towards the Red, the worse it is.

Some people have noticed excess Knock after simply filling the car up at a petrol station. This would be a result of a poorer quality batch of fuel.

The point is it would tell you how bad the knock was and you should immediately back off until it goes away.

if it's constantly lighting up like a Xmas tree, then something is wrong and you would need to get it looked at. It doesn't necessarily mean it's just about to blow up, but it lets you know that it's happening before it goes too far and any damage is done.

IIRC, the ECU uses inbuilt knock correction to adjust the air/fuel mixture, advance timing, etc..

According to John Banks experience tuning cars with the DeltaDash software, cars can simply ignore any (or all) knock above 5,000rpm.

Stefan

UHF

i see, so if I'm getting xmas tree effect I go to a subaru tuners and say "i got xmas tree on my Knocklink, help!" Are there places who fit all fo these gadgets? and can sort it all out?

58GT

If I had the old Back box still I'd whack it back on and just check it was that causing the prob. Sometimes you think the cause is one thing when it's something else.

UHF

its def the back box, I drive the car everyday to work and use the same roads day in day our, drove to work and was ok, drove home with new box and was bad, I understand your reasoning though, it might still be worth doing that cos the car was in for an MOT at the same time as the box so perhaps they screwed something else at the time.

Fat Boy

Decat will potentially cause problems due to the car breathing much better. It will be less restrictive so you get a higher volume of air compared to fuel after decatting ie it runs lean. The problem with this is the fuel not only provides go but also acts as a sort of coolant; if temperatures in the cylinder rise due to a lean mix then you can get pre-ignition of the charge AKA detonation or knock. Basically the fuel mix will ignite too early in the cycle ie when the piston is still coming up the cylinder and the shockwave will hit the top of the piston. Over time (and this can be a variable period depending on the severity of the knock) it can blow a hole in your piston and wreck your big ends as well.

By adjusting the timing this can be reduced or eliminated, and the standard map in the ecu will try to counter any detected knock by removing timing (and hence power). As a result and at best your car gets slower, worst case, if the ecu misses it or there is no provision on the map for the area the decatting has now taken the map into , you can blow your engine.

Countermeasures are Octane Booster (NF Race IMHO), Knocklink so that you can see if there is any knock and back off - might just be bad fuel( ie supermarket fuel etc) or it needs some more Octane booster, Lambdalink/afrmeter - tells you whether the fuel mix is rich or lean ( but not whether the fuel is any good or not) and the ultimate fix- an ecu remap by a respected mapper. This will tell the ecu what to do at any point in the rev range as a result of your exact car's condition. In other words your car comes with an off the peg standard ecu but every car is different to a greater or lesser degree, after you decat the breathing will have changed significantly so , if you remap, you are effectively resetting the safe (and more powerful usually) limit for your car. It's like the difference between an off the peg suit and a tailor made one. One fits most people alright but it's nothing special, whereas the other one will be spot on and will give you more smiles.

UHF

so are you saying that with a decat and without a remap my car will be the same if not slower?

As in is it worth me going to spend £400 at scoobysport on Friday cos I dont have any more money until the end of the month to spend on my car and I wasnt thinking of spending any more.

Who are good for remaps anyway, i've seen the ecutek stuff that powerengineering do, but they are for upgraded performance, I just want my decat to run safely. If the bottom line is that its decat followed by another £600 to run properly then i'll phone tomorrow and cancel it