I'm going to be doing a few more mods to my 1998 UK Impreza:

TD04H
440cc injectors
Ported headers

I already have a Knocklink and the boost is controlled by a Blitz Spec-S EBC. The four settings I have are set for:

1. Approx 0.8 bar. The wife, and snowy conditions (very useful actually)
2. Approx 1.1 bar. Normal day to day running
3. Approx 1.25 bar. When I want that little bit more.
4. Approx 1.35 bar. Only used if I have Optimax and NF in the tank. (Shootouts, etc LOL )

I know the ECU is out of the equation for tuning, as MY98's are not mappable.
Would a Lambda link, or an AFR gauge be best for checking/monitoring the fuelling?
Is there something else I should be doing?

The theory behind the injector change is that 440's will flow more fuel than the 380's without any changes to the ECU. Maybe I'll need to fit an induction kit to allow more air in to redress the balance?

Any hints and tips much appreciated.

ps: Andy F/Harvey......I haven't ignored your words.....I'm just after opinions from others that may have done similar mods.

 

if you have 440's with the standard pressure (and a map for 380's) would there be any difference in fuel flow?
I think you would need to look at upping the pressure

 

Sorry....should have put that I'll fit an SX regulator too!

 

You could buy an A/F meter from http://www.3barracing.com (formerly dawesdevices) for $60. It will link directly on your ecu and you will know if you are running lean. Another thing is you should properly upgrade your fuel pump for a more reliable fuel flow.

 

IMO do not rely on the OE lambda sensor so set meaningful AFRs on boost, its not designed to do it - the voltage range for the AFR's you want is tiny and they tend to under-read at high EGTs.

TBH over fueling on boost is going to reduce power. The OE ECU runs rich anyway.

I would suggest sticking with your 380's, full decat, uprated panel filter, remove resonater, boost no more than 1.2 held and use a knocklink to monitor det.

And save your pennies for a PFC

 

Full decat.........DONE
Panel Filter.....DONE
Resonator........DONE
Boost 1.2 bar......erm.....gone past that
Knocklink..........DONE

Can I fit an aftermarket lambda sensor to get the correct readings? It must be possible and feasible, coz plent of people seem to fit Lambdalinks.

ps: already got a Walbro 255 pump fitted.

 

Fitting larger injectors will cause overfuelling unless the ECU is tweaked to match, it will result in less power, more engine wear and not give the results you want overall. You would be much better off saving the money you would have spent on the knocklink, SX regulator and boost controller and spending it on a PowerFC (with commander and mapping) which will give you what you want with better overall results.

Paul

 

Presumably your boost rolls off at about 6000 RPM to about 1.0 bar?

You should be hitting fuel cut on settings 3 and 4. Any sign of it? Fuel cut defender in there?

I think your standard ECU, MAF, injectors & fuel pump will handle anything you can throw at it on the standard turbo. The exhaust manifold pressure from the small turbine wheel and housing will help to open the wastegate at higher RPM, hence my interest in the roll off at the top.

If you want to check the AFR, a wideband AFR is the only way to do it reliably without guessing. It is leans off to weaker than 11.5:1 I would change the fuel pump and see if it still does. If it knocks, use more octane or turn the boost down.

There are lots of other ghetto things you can do, but to do them properly you'd have the understanding required to be able to map an ECU yourself, and a PowerFC is very cheap.

 

OOpps......I knew I'd forgotten something!!

Yes....there's an HKS FCD fitted too. I ran for a while without it, but that was when I was using a Dawes type device to control the boost. I managed to get it maxed up to just under fuel cut....was about 1.1 bar IIRC. That's when I got my 244bhp at Well Lane!

Hmmmm the Power FC option seems to be looking more and more like the way to go. I was going to get a TD04H from Andy F, but maybe the PFC is what I should buy instead.....I think he's also the man for this........I have read good reports about his work.

If I go for that, then I guess I'd probably get about 270bhp? Isn't that about all a standard TD04 can muster?

TBH I was looking at "Ghetto" (I like it John) mods first, as I was hoping I could run with reasonable engine safety until such time that I could buy either a Power FC, or another, newer Scoob (and sell all my bits and bobs).

So....to sum up.

440cc injectors are a waste of time.....shame coz I've just bought a set.
Ported headers worth fitting.
TD04H worth doing.

But.......injectors and turbo would need Power FC to have the car running correctly and release the potential of the parts?

Would you recommend a particular make of wide band AFR? I've seen a few like Autometer's digital gauge, but not looked at the band width. Is a Lambdalink the same thing?

With regards to Det'....I assume not det' is good det', but it would seem that lots of people get a bit at times. I have seen an occasional flash of the red on my Knocklink, but it's generally only been at higher revs and as the revs rise past about 5K. It may give one flash and then nothing more than maybe two greens.

I very much appreciate your feedback lads. It's what Scoobynet is all about in my eyes. Getting advice from people that know more about stuff than you do.
Many thanks for the advice so far.

Confusing this tuning lark innit?

 

I would recommend saving the wideband money, and putting towards having a decent mapper set it up. What do you mean by td04h wrt the turbo? Do you mean a hybrid td04 or just the TD04h standard turbo?

Paul

 

Widebands can be had for around £140 to aid with the ghetto approach but as Paul said you should really be looking at a APFC or similar.

 

TD04H is a modded TD04 from Andy F. (AFP04H I think)

Holds boost a lot better apparently.

Looks like Power FC is the way to go then. Will I see benefit, even if I keep my standard turbo?

Basically....if I need to chage turbo AND fit a Power FC, it won't be done at the same time, due to funds (or the justification for the spending of......)
I'd like to do it in stages.

 

If you get near the figures Andy achieved, hold on to those 440's

 

You can fit the power fc without the turbo and you will notice a massive difference to the way the car drives and probably also to fuel economy. I know I did. You can fit the turbo at a later date and then just get the mapped tweaked, this is what I aim to do as it was found during mapping that I didnt have the tdo5 turbo that I should have had.

 

Assume that the flashes of red on your knocklink are damaging your engine.

 

Yup....that's the attitude I adopted.

Fortunately it tends to have been when I've sneaked up to setting 4 on the boost controller and (very naughty) haven't had NF in the tank.

If I have optimax on it's own, I use setting 3 and below....no red flashes.
If Optimax & NF.....no red flashes.

If I can't find Optimax when I need it and have to resort to Super Unleaded from another supplier, I always keep to setting 2 or below.

Sorry John......missed your earlier bit in your reply.........the boost does tail off towards the top end of the rev range. I guessed it was just the characteristics of the TD04, although I was told that the wastegate actuator arm could be tweaked to help this.........I wasn't brave enough to try it. Thought it was best left alone.

 

The Autometer AFR gauge is a 19 segment LED meter, which runs a pretty wide range and will hook up to an OEM lambda sensor signal. I can't remember the exact numbers off the top of my head, but I'm pretty sure the range was somewhere around 10.5:1 up to around 16:1. Now I can't say I'm an expert on Subaru AFRs in particular, but common sense would suggest that the OEM sensor with an Autometer gauge hooked up would give you all the information you need. It certainly worked accurately for me (not in a Scoob btw) on the road, at the dragstrip, on the dyno and around the 'Ring. And stop me if I'm wrong, but if you're driving around with a car that regularly runs richer than 10:1 or leaner than 16:1 (apart from on the overrun) you've got a major problem that a fancy 'wideband' AFR reading isn't going to fix.

A wideband is a good garage/tuning/setup tool, but I can't see how it's necessary at all in a road car. Monitoring of the standard OEM lambda signal is as much as you need. Problems with the AFR will show up straight away on an Autometer.

 

A narrowband lambda has a non-linear response that is temperature dependent and variable between examples. Its only legitimate use is to identify stoichiometry.

Subarus are more susceptible than some to lean mixtures for three reasons: turbocharging, uneven air:fuel mixtures between cylinders and tight bore clearances.

It is possible (and I have seen it) to have a narrowband reading of 0.89V and be excessively rich under full power (10.5:1) on one example and lean enough to cause trouble on another (eg 12:1).

With stock induction, non clipped MAF signal, acceptable IDCs and fuel pressure that is not dropping you're unlikely to run into trouble on the stock turbo/ECU from fuelling, you'll probably just run too much timing as you might run off the end of the map.

 

Erm................

Looks like a PFC then!!!

Saves a load of messing about with "ghetto" modifications, and also I can me more certain that the car is set up correctly for the current mods.

I'll see an improvement and can always re-map as and when I do more mods'.

I assume I can stick with my Blitz Spec S boost controller for now? Is the PFC set up for the highest boost setting I'd run and then the car will run acceptably if I turn the boost down for say.....non-optimax fuel, etc, etc?

I assume fitting the PFC would allow me to remove the FCD....it would be redundant. (acronym city here IMO)

How about if I occasionally want to run with Optimax and NF (like for a shootout or something) (only do this now and again at the moment)....will it just give me the extra margin of safety for knock, or would it be a waste of time with the car properly set up for Optimax only?

Cheers for the info so far peeps.

 

Fitting the power fc would allow you to remove the FCD.
You can use any fuel when you get it mapped, eg if you want to use normal unleaded, fill the tank with that before the mapping starts, you will still get a very good power gain with improved driveability, you could then still increase the octane however you probably wouldnt gain much if anything as the car was mapped for a different fuel. It probably would help with knock though.

 

The PFC has four boost settings. You could sell the boost controller & FCD. You could still map higher ones for higher octane fuel.

 

PFC is just such a nieve piece of kit. It can do the job of so many other quite expensive gizmos.

If it were the case that you felt you could map the ECU, and to hell with everyone else, then by all means just get on with it. This is pretty much what a number of us did back in the day, but if I could have started with a PFC instead then I sure wouldn't have spent days and days trying to frig an OE ECU!

John is too modest, he and Andy.F are the kings of ghetto tuning, and while it can most certainly be a cludge/frig/fix it can tell you things, and John has frigged more things that I car to think about If you want to get into tweaking a few things, then the PFC is a good way to do it, and will allow you to actually control a useful range of parameters rather than a blanket change like fuel pressure or injectors. Just get it setup properly in the first place.

Paul

 

Don't I need the Apexi Boost Control Module for that though?

 

No you don't. The boost control kit is only need on pre97 cars that can only be set to 1 bar with the OE map sensor, OR later cars when you want to run over about 1.7 bar (1.8bar sensor limit).

 

Last question......probably.

How do you switch between the four boost settings on the PFC?


SCRATCH THIS QUESTION..........It's done with the Commander!! (I know now)

MANY THANKS FOR ALL WHO HAVE RESPONDED AND OFFERED THEIR ADVICE.

I'll be taking the Power FC route by the looks of things. Going to have a chat to Andy F in February....see what he can do for me.