CJAF7R

When i got the car, first thing i did was fit a knocklink, it was detting slightly at high revs, so iv driven it under 5.5k and not really flat out till i solved it!

Anyways fitted an sti5 intercooler, after a day or so it was much better (did the car have to adjust?) still got a few greens tho and the odd amber so again kept a close eye on it!

Anyways got an sti panel filter, and standard airbox, was missing a plenum so have finally got one of those!

Fitted it all just now, and what the ***, feels slower, its loads quieter, dump valve is hardle noticable compared to before! but no knocklink activity other than the odd flicker of the first green which is good!

but whats happenin, i thought the standard box with sti filter was a better option than an IK??

Will the car need to adjust! actually will i need to do an ECU reset?? just thought i havent done that!

Cheers for any advice!

Plucking Pheasants

Going from a cone to the standard airbox does make a noticeable difference.

I went back to the airbox because I got fed of all the whooshy noises drowning out the exhaust and basically sounding like I have a burst hose on my turbo (IMO - of course )

I think it made about a 200rpm difference in lag. I hit full boost at around 2900 rather than 2700rpm with the K & N cone. But boost seemed slightly more controlled and car is slightly smoother to drive round town.

One thing I have heard about from tuners with cone filters is they can make a slight difference to the MAF readings (laminar airflow, Turbulence and stuff like that). This in turn could mean the mixture weakens slightly to the point it starts to det. Bearing in mind Subarus at full boost are running rich, so a slight weakness in the fuel mixture would give a little more power, at the expense of detonation.

The other explaination could be more restricted airflow. But that simple argument doesn't work, beacuse at full boost the turbo will always try to hit its target pressure which is accomapnied more or less by the airflow. Unless the turbo is running out of breath at high revs (around 5500rpm on a TD04 with standard mapping), in which case you may see a slightly larger drop in boost pressure with the standard airbox over a cone filter.

PP

andypugh2000

I re-fitted my std airbox with a panel filter after taking off the K&N I.K and it was a lot slower in power delivery.

After 4 months of it being on my driving has adapted to it so now I am going to put the cone filter back on and see exactly what it does

AP
MY98 Turbo

Gear Head

iTrader: (2)

'Bearing in mind Subarus at full boost are running rich, so a slight weakness in the fuel mixture would give a little more power, at the expense of detonation.'

I think you will find that the impreza turbo actually runs very lean at high revs and is why so many blow up doing 140mph +!

Plucking Pheasants

Not mine!

But if I had the full decat, and put the K&N back on without touching the ECU mapping (which I guess aload of people on hear do) it could potentially run lean, boost spike and det inaudibly (det that you can't hear). And without the instruments or guages to detect that I, like alot of others would be non the wiser. But I have a AFR meter and knocklink, so I do know!

The ECU at wide open throttle runs in open loop (doesn't use the O2 sensor), and purely depends on the MAF readings based on a standard setup. Start messing around and you could potentially create a situation where it underreads slightly, or the fueling map table stored in the ECU doesn't correctly correspond to airflow measurements.

Doing blind modifications and and not taking into account the subsystems it affects and not expecting a blow up 140mph is rather shortsighted by any standards (yawn...much more fun to do 60mph round some twisties anyway!).

The only Subarus I have seen blow up at speed are either: Modified (most done badly..unmapped or badly mapped), Incorrect fuel (JAP import, not mapped for UK fuel). Component failure (such as MAF sensor), or the toll of 60000miles of pure ragging and hard driving without changing service intervals and oil specifcation.

andypugh2000

K&N now back on........Much more responsive and free revving, its staying on there now, I think i can live with the noise for the sake of a much better running car

Oh and I never do 140mph just up to 70 on twisties

AP

Plucking Pheasants

Just curious, did you reset your ECU when you did both swaps?

andypugh2000

Nope, never bothered to reset it ever

Plucking Pheasants

Perhaps, maybe you should have then?

morpheous

iTrader: (9)

I think you will find that the impreza turbo actually runs very lean at high revs and is why so many blow up doing 140mph +![/QUOTE]
Not mine either on more than one occasion

Ive always run the std a\box with k+n panel no probs (as he grabs a lump of tree wood) All monitored but maybe i should go i\kit ? and see if theres a difference but maybe not prob go bang lol..
If it works for ya dont mess!

andypugh2000

Why????

andypugh2000

I went from induction kit to K&N panel filter and found it less agressive, an ecu reset is not going to make the panel filter flow like an induction kit.

Upon replacing the induction kit the raw power and aggression is back

Daz34

How about one of these?

Scott.T

iTrader: (2)

As mentioned above the induction kits can confuse the MAF reading to the ECU. Hence the calculated load is lower and the ECU runs lower on the load scale of both the ignition and fuel maps.

The lower down the load scale you are the more ignition advance is applied and the leaner the mixture. This can be of benefit as more ignition/less fuel = more power. However, it can also cause detonation and a hotter burn.

CJAF7R

Cheers for the input! Bit of an update as iv driven the car more than 3miles today!

The car does feel a lot smoother, and much nicer to drive off boost, it definately doesnt feel as raw, but its nice to be able to hear the exhaust over the induction noise and turbo! the dump valve is a lot quieter, but it sounds a lot smoother too!

but the most important thing! virtually no knocklink activity at all! I was getting 2 greens and the odd amber, but now rarely get more than the odd flicker of the first green which im happy about!

gonna leave it all week and see how it goes! im sure the car feels slower, but it could just be in my head due to being quieter! the car doesnt feel as snappy as before, not as much of a kick on boost! ill do some tests on bits of road i know i can get certain speeds on!

CJAF7R

actually!!

What is the best IK to have?? If I purchased a good one, then had a remap would this overcome any detting probs using an IK?

Scott.T

iTrader: (2)

A bigger intercooler such as a later classic or any of the STi ones, may help. But it is more then likley going to give you approx 1psi more boost due to less of a pressure drop accross the intercooler.

A friend fitted an MY98 cooler to a MY93 and got 1-2psi more. But no more det running a panel filter.

This still probably won't help the induction kit to stop detting even with the cooler charge air.

CJAF7R

iv already fitted an STI5 intercooler a couple of months back. This made a nice difference over the early slanty one, and reduced any knocklink activity! but not completely hence the panel filter over IK

iv been driving steadyish since i bought the car just to be on the safe side!

the car was boosting to 1.1 bar, but now iv fitted the standard airbox im sure its only boosting to 1bar!

Scott.T

iTrader: (2)

give the actuator a couple of turns then, that should bring the boost back up i.e shorten it.