Seraph

I drive a STI Ver 5 Type R (Jap Spec). I am considering a Possumlink ECU upgrade. I hope you guys can share your experiences on the following:

1. Does STI 5 benefit much from ECU upgrade as I understand that it comes with STI tuned ECU (whatever this means?) I get 1.1 bar on 4th and 5th alreadly. Can the car be tuned further without engine upgrade?

2. Will I get significant gains from ECU without changing induction and exhaust?

3. My car comes with Intercooler spray (Automatic). Is this ECU controlled? If so, can Possumlink perform this task?

4. I have read the Possumlink manual and it seems almost impossible-for me :-( to get all the zones as I don't even understand timing advance and fuel maps! Can Possumlink be tuned by uploading tuning specs which can be downloaded from Internet etc? Is there any tuning specs available for STI 5?

5. Can Possumlink support anti-lag? How?

6. I understand that Possumlink comes with optimised settings for MY99. Is there a per-set for STI?

7. Can the tuning module be used to tune the car on the fly? (After I learn it of course)

8. What tuning options/methods and software are available with Possumlink system?

9. Any other feedback on other ECU options would be appreciated.

Sorry for the 1000 questions, but ECU is a complicated subject to me. Thanks in Advanced

Lee

I thought I'd stick my oar in..

If you don't know how (or can't) tune the Possum yourself then surely you're wasting your time with it (plus the obvious damage that may result from "playing").

Bob Rawle has a Possum Link..he is (IMO) the absolute fountain of knowledge about the cars/maps etc and has produced more power from Possum than a PE remap.

The beauty of the Possum is that you can make adjustments yourself. If all you wanted to do was download maps then why not get someone to sort you out a proper map and stick with it ?

Bob Rawle

Seraph, the Link ecu is suitable for all cars from 1992 to 1999 and comes in different versions to suit the varying ecu connectors used. It comes with a default map that means you can plug it in and start the car but it will, for certain, need to be tuned to suit your particular car. Currently there is a "bug" in the MY99 software that cause a STi 5 to possibly have a big flat spot. Its to do with the fueling and the transition from group to sequential injection. Link are working on this I believe.

Yes it can be setup on the fly, yes it can minimise lag, yes it supports the auto water spray and can be programmed to suit. In fact you can set it up any way you want but ... in order to do so you MUST understand how an ecu works and what interacts with what on the car. If you don't then you can cause a large amount of damage. The default maps will enable the car to be started and driven but could be a mile away from the actual settings needed.

Have a look at

Anders

The Automatic water spray is driven from the ECU.

Seraph

Thanks for the info so far. I'm suprise that BPM has not yet responded.

Bob, thanks for the URL, it's brilliant. However,I've studied the Possumlink throughly and can't seem to find the STI waterspray control option. The Possum also seems only capable of controlling zones up to 8000 RPM. Can it manage higher RMP zones? I seem to be able to rev to 9000 on my standard ecu-by accident of course

Also, is a set of performance tuning maps/settings available for the STI Ver 5 type R for reference?

Bob, being the fountain of knowledge on the Possum, can you please provide me some advise on tuning the Link for STI 5? I am seriously interested in this upgrade!

[This message has been edited by Seraph (edited 18-09-1999).]

[This message has been edited by Seraph (edited 18-09-1999).]

Bob Rawle

Seraph, I've had a look at the MY99 Link manual and it does not refer to the "SPRY" setting that my manual has. I would say then that the water spray is initiated by some sort of pressure switch dependant on boost and is not ecu controlled in the MY99. Perhaps someone with a "5" knows ?

The settings for 7500-8000 will be used if the engine revs above 8000. Why would you want to do this ? Its of no benefit from a performance point of view as peak torque/power occurs much much earlier in the rev band. It will definately stress the engine.

As far as I know there are no settings readily available. Someone somewhere will have done it but if they don't read the list then ...

BPM have said they have a setup for the "5" but it will only be a starting point.

Advice I can give but its not possible to map an ecu by email, you have to see and feel what is happening with the car and make decisions accordingly. I can give you some basic do's and don'ts if you like but best off list I think. Let me know. Don't forget that the "5" is currently thought to be "difficult" due to the fueling thing. I'm told that standard WRX cars (equivelent to UK spec) are no problem.

Seraph

Thanks Bob . Wonder if you know whether the STI tuned ECU is running the car near optimum, or very conservatively? My car is STI Ver 5 Type R.

Basically, I am trying to get an idea of whether it is worth while swapping my ECU for the Possumlink. Also, does link support Anti-Lag? Is this just a tuning thing or $$$ option. Are you driving a STI? Do you know what boost the engine can handle without upgrades?

Being a Possumlink user, did you have to change any of the std sensors, e.g. MAP, LAMBDA etc?

Lastly, what is the fueling thing problem you refered to? I try to use at least 98 octane petrol at all times.



[This message has been edited by Seraph (edited 18-09-1999).]

Ian Cook

Anti Lag would be very very costly on a road car. It keeps petrol going into the turbo and detonates it to keep the turbo spinning to cut the lag. On the rally cars this means the engine is rebuilt after every single event. Not the sort of thing you want to do with a road car, every 1-200 miles rebuild the engine. You would last longer running 95 RON Unleaded in your STi 5 before the engine blew.

Bob Rawle

The STi "module" is just a set of perceived typical values. It will be good in one car and average in another. All cars are different and need specifically setting up for optimum.

You can minimise lag by using the ecu's settings correctly. as an example my car was producing peak torque at 4600 rpm, with the link it produces it at nearer 4000 rpm. Thats because I've set it up so that the turbo spools earlier with some small amount of overboost.

All the standard sensors will work fine. the link does not use the maf sensor so you could remove it if you wanted. The map sensor in a 5 is linear up to 1.4 bar and that should be plenty of boost if you want to keep you're engine intact. (not suggesting its safe at that ... its not !!)
My car is an earlier model and the map sensor is only linear to 1.3 bar, I use a Cosworth map which has the same callibration as links own. This is allowed for in the ecu program. You should use your standard one, its fine.

The injectors are fired in "group" mode until they hit 20% useage. At that point they change to "sequential". Group means that all injectors fire at once so there is lots of background fuel and the settings have to take this into account. When you change to sequential the settings have to alter significantly as there is no background fuel anymore. Its difficult to get right and can lead to a flat spot as the mixture changes from rich to weak.

On a previous car (not an Impreza) I used a fifth injector that fired every time to provide background fuel. I had a hybrid turbo fitted that used Cosworth wheels and so the standard injectors couldn't cope above 3500 rpm on full throttle. Doing it that way meant I still retained some economy and drivability because I set up the fifth injector to only start to work above a fixed boost pressure.

Don't forget that you will still have your old ecu. You can swap them over whenever you like.

Bob


[This message has been edited by Bob Rawle (edited 19-09-1999).]