Marcos

Hi - just had fitted a Magnex backbox and Blitz induction filter to a 95WRX.

OUTCOME:

1 - Luvely low beating noise from exhaust, nice sucking induction noise and even the BOV can be heard now :-)

2 - Haven't 'really' noticed any difference in power or throttle response - however its early days yet... I even think that the power delivery is smoother now, not so jerky as before (ironic?)

QUESTIONS:

1 - What really is the difference between an induction kit and a simple panel filter system? I have scoured the positings and not really found a suitable answer.

2 - Why is low down torque reduced? Some people say it gone up? IS the torque/revs graph changed - this might explain my different feeling of power now in the car.


3 - Why would fuel economy go up?

4 - Why do I now hear the BOV :-)


I'm sure there's a great website somewhere explaining all this - however I would be very interested in your replies,

cheers

marcos

GavinP

Marcos,

I have fitted a Remus backbox and Pipercross induction kit but the benefits should be broadly similar...

The backbox reduces the "strangling" effect of the OE backbox at high revs. I don't notice a huge difference below 5000rpm. My car now revs to 7000rpm (up from 6600 approx.) I would assume a replacement downpipe or centre section would influence pickup more at low speed.

The induction kit increases noise substancially but seems to reduce the spool-up time of the turbo due to the increased amount of air available to the engine. The higher quantity of air flowing through an induction kit is the main advantage over a panel filter.

The fuel consumption increase seems to be due to better efficiency when driving hard (i.e. high revs) but town driving does not seem to have changed.

Although arguable, it may be worthwhile performing an ECU reset to set the engine management system (run a search on the BBS).

Thanks

Gavin

[This message has been edited by GavinP (edited 09-10-1999).]

Icepic!

There is no benefit whatsoever in an ECU/EGI reset. This is a myth, anyone claiming this has an effect obviously has no real knowledge of the internals of the Subaru ECU/EGI (as based on a Unisia/JECS design).

If anything, you will slow down the re-learning process. Leave the ECU alone to do its job. It is smart and fast enough to compensate for most alterations within 3 seconds whilst under WOT.

Further, the ECU does not maintain maps of pinging - they are simply 'blackspots' within the rev range that are demarcated for retarded timing and said timers are decayed at a steady rate (over some 30 seconds) until they disappear (unless there is more pinging in which case said timers are reset back to a 30 second count).

Icepic!



[This message has been edited by Icepic! (edited 10-10-1999).]

GavinP

Icepic!,

As mentioned in my post, the ECU reset is a debated subject but I like to keep an open mind.

Having said that, I have tried it and it made no difference to my car but others have reported favourable experiences.

At the end of the day, it is down to the members of this BBS to read and make up their own mind - the vast majority are very intelligent.

Thanks

Gavin

Bob Rawle

Icepic! ... why are you hiding !! What is your email address.


Its been clearly stated that the ecu "reset" is a myth. All that happens is that ecu is forced back to defaults. From there it learns ... If ecu was at optimum already ... no benefit ... if not then some benefit till it knocks itself back again.

Timer theory is valid IMHO ... the Bosch system in Europe is almost instantaneous though and "trims" individual cylinders. Its hard to believe that Fuji Heavy Industries have not caught up ... unless you are refering to a model year range.

mike_nunan

Hmm. David Power told me that the ECU does maintain a map of "blackspots" and that this can take some time to clear if the cause of detting is removed. This makes sense if you think about it. Otherwise, the ECU would have to keep advancing the timing, hear the detting, then back off again.

The point is that you don't want to deliberately induce the detting too often just to check that it's still there, like someone poking a sore tooth to see if it hurts. I don't see how a system could adapt within a fraction of a second without letting the engine det in this way, which surely can't be good for the pistons.

Icepic! and DP, do you care to continue this discussion for our general elucidation?

-= mike =-

sonu

Marcos

in reference to question 2, I have found that low end torque has increased dramatically. I have a Magnex backbox and Ramir filter panel. If anything, low end toque should improve with the backbox etc.

Thanks

Sonu

pat

While testing another ECU (long story) I inevitably reset my original ECU (hey, I had to transfer the four plugs over, so cut the power to the original ECU). After testing I plugged the original ECU back in and there does appear to be an increase in torque. I'm not sure why, yet... it could be something completely unrelated.

The ECUs (at least the '95-'96 Japanese ones) are indeed JECS units. Reasonably well put together, but for some bizarre reason using (AFAICT) linear regulators rather than switchers.

As for knock control... different manufacturers use different knock control schemes. Take the Totoya 3S-GTE engine, for example. The ECU continually runs the engine on the limit of knock, adjusting advance about 10 times per second. Despite this, the engine is one of the most reliable you'll ever come across, and one of extremely few which can survive a cam belt failure without any damage to the engine (non interference design). The Subaru ECU seems to take a wee bit longer to adjust its timing :-(

Cheers,

Pat.