Doidge

Looking to change the air filter on my 02 plate UK impreza WRX but have told it can't be done as the MAF sensor is part of the actual air box, and when you change it, it completely messes the MAF up. Is this right and if so whats my best option??? Just a replacement panel filter?

Thanks

Turbotits

iTrader: (2)

No its all wrong,The filter can be changed, The maf is in the tube after the filter box and can also be removed from the tube. Although induction kits can mess up the air flow, so the maf may need re-scaling

Doidge

o right, so how do I go about doing it then?

has anyone got any more details on this?

many thanks

corradoboy

Change it, easy peasey. Undo four clips and pop off lid to filter housing, pull old paper jobbie out, drop in new Green, JR Racing or K&N filter, reposition lid and reclip. For a bit extra (or maybe not ) look at removing the intake resonator and ram-air scoop (do a search). Makes the induction and dump valve more audible, and I thought the intake temps seemed lower when I did mine too.

I/K's are a bad idea on a Scoob. The standard intake is well designed and copes perfectly well to over 350bhp. I/K's can damage MAF's through vibration, upset fuel air ratio's and reduce power due to increased induction temps due to drawing in hot engine bay air.

Doidge

O right, thanks for the reply

So whats the best filter to go for, for the best gains and where can I get it from?

Thanks

corradoboy

Don't think too much about gains, it will be 1-5bhp max and so virtually un-noticeable. The primary reason for one is to avoid having to keep buying the OE service items, and they usually allow a little more induction noise. The increased flow rates are more of a benefit later when other mods require more flow. If you're chasing power look at fitting a decat up-pipe, decat or sports cat down-pipe, a decat and deresonated centre section and a free flowing backbox. Allied to a remap and with the filter this should get you 280bhp or so. Leave the power alone after that, as your Scoob will be much faster if you then concetrate on the suspension and chassis to address the power to handling imbalance which always occurs when people start tuning Scoobs. Save a few quid to uprate the brakes too. Lines, fluid and pads are the minimum to cope with the power upgrade. Also think about driver tuition. The biggest perfomance increase I ever got was after spending a full day with a Police Class1 Pursuit driver learning Roadcraft, and it's a mod that transfers to every car you'll ever own for life, and possibly saving your life too.

Doidge

I have an 02 WRX, it has a prodrive exhaust fitted. I think theres a cat taken out, but maybe 2 more still in. can anyone varify this? If so what are the best decat pipe(s) to go for?

I've also been looking at getting a walbro fuel pump, do these increase performace or are they just better for the engine?

Thanks

corradoboy

It sounds like your car may have the PPP (Prodrive Performance Pack) fitted, which on the 02 consisted of a decat centre, BB and piggyback remap chip IIRC, and should be getting IRO 240bhp. You won't need a Walbro unless you plan further mods like a bigger turbo, higher flowing injectors and better TMIC.

funkyspider

If you remove the cats you will need a remap which will ad 650ish to the bill.

If you are running (and keeping) the wrx TD04 turbo I recommend the magnex slip jointed decat up-pipe as the smaller diameter helps early spool up of the turbo. For larger turbos the H&S slip jointed up pipe is good.

Another point to note about decatting the up-pipe on a wrx is that you will need to remove the EGT sensor as the standard one cant cope with the higher temps. This will raise a CEL, although this can be easily fixed using a 2.2k Ohm resistor.

If you want to stay legal and have hassle free MOT time then fit a high flow cat downpipe. I went for the PPP item fitted with the STi PPP pack, works fine and below 'higher' tuning levels (ie when replacing turbo/injectors on a wrx etc) has very little effect on power.

The combination of magnex up-pipe, PPP downpipe, K&N panel filter, fuel pump and a remap on my MY01 wrx gives a much better all round drive. Add to this a whiteline rear ARB with solid drop-links, uprated brake pads (Mintex M1144 for me) and braided hoses gives IMO a much improved car over standard.

Funkii Munkii

Sorry to jack the thread,
FS I have been running a 98 Classic for 9 years on ITG filters and that was a noticable difference, well to me anyway, today I Bought an MY01 Wagon with PPP (265 bhp) I was considering a new panel as I felt it would benefit, AFAIK I can pop a new panel in no mapping or anything else, can you confirm my thought ? also what benefits have you noticed with the K&N panel over the standard or other examples.

Many Thanks

FM

The rookie

iTrader: (1)

No mapping needed, and if you read the thread it already says 1-5bhp.

Simon

corradoboy

Funki, you've done well to get away with ITG filter on a '98 car. They are infamous for causing MAF failure due to excessive oil used on the filter membrane transferring to the MAF. 98-00 cars were particularly bad as they used a hotwire MAF which fails if you fart near it. If the MAF does fail you get an uneven idle, a flat spot in the power delivery at about 4k revs and then a melted engine.

Funkii Munkii

Corradoboy, Blame ScoobySport they talked me into it , and its still flying at 168000 miles!!, I have been using the ITG panel since 40000.

I always thought I had a special Scoob, all those miles, flogged around the M25 6 days a week, and all I have had done is a Rad at 130000 speed sensor at 160000 and a fuel pump 2 weeks after the sensorand still the original exhaust bar the SS back box at 40000, original clutch etc etc and it feels as nimble today as it did 9 years ago, to be honest after todays drive to Silverstone and back I was thinking I'm really go to miss this car when its gone, crazy when I'm collecting a mint 32000 mile MY01 bugeye on Saturday, never been so attached to one car, maybe i'll keep her for weekends



I have read it and I didn't ask what the Bhp increase would be, I asked what benefits, maybe I shopuld have written characteristics to have aided your response, read the post wannabee pedant