Prodrive Brad

Right, hoping someone can help. This will seem peanuts to the big tuners here, but we all have our own pride and joys, I love my car just as much as the next man loves his. Help would be appreciated on this.

I know this is fairly common and I have searched, but frankly what i've found isnt specific to me and what im trying to find out, so (violin back in the case) ..........

I've recently bought a 03 STI Type UK PPP.

PPP confirmed by Subaru UK, im assuming the ECU is the PPP one (havent actually checked) seems to be a custom back box on the car (not the OE prodrive stamped one) HKS SSQV dump valve and as far as I know, nothing else done to it. I dont know when the DV was fitted, I wish I did. Unfortunately I want to keep it, I know most of you will say its causing the problem, but id prefer a workaround.

On 'some' days it is a little bit rough from cold in the low revs and very occasionally feels rough at low revs day to day in commuter traffic when warm. Other times, pulls like a train absolutely no problem. It felt particularly rough starting it the other day after around an hours motorway drive, then left over night and started in the morning. Once warmed up after around 4-5 mins, was back to normal.

The car has started randomly popping from the exhaust, so suggests overfuelling. Popping from the exhaust only seems to happen again at low revs, when the car is FULLY warmed up, when driving very slow changing up to high gears (ironically when im driving in a fashion to save fuel!)

I have no idea whether the car has been re-mapped in its life. Im based in Birmingham.

What should I do? Presumably I cant just leave it and it'll be ok, I dont know the charecteristics of these cars as im new to them.

My head is telling me get it looked at, but a part of me doesnt want the map messed with. I need this car day to day for work, just want it to work basically, keeping the dump valve. am I asking too much?

Where can I take it where someone knows what they are doing with it and can understand the problem?

Scoobyworld??

chrisUK300

iTrader: (10)

Scoobyclinic aren't a million miles away (chesterfield)

Can't offer any advice on your problem though sorry.

madmarx

iTrader: (1)

Could be a million and one things. The way you say it is on off etc, eg not all the time would suggest it is not a mapping problem, maybe an electrical component that is fluctuating and going off its normal reading etc. Service and new plugs is always a good start.

Maz

iTrader: (34)

Sounds like it's running very rich in the lower part of the rev range. Very similar to what happened to my first Impreza when I had a vta dump valve fitted. Try swapping to a oem recirculating dump valve to see if that alleviates the problem.

Gigsy

A VTA dump valve will tend to cause the car to run rich for a short while after it has vented since you're losing metered air so I'd definitely swap to a recirculating DV unless you really like the sound. It might not be your problem but worth a try if you have one to hand.

Other possible causes that spring to mind for me would be a faulty sensor or possibly idle control valve.

If you're able to, do some data logging and see what's happening as it's very hard to diagnose a fault simply via a description or failing that, as been mentioned, get it down to a specialist to have a look at.

chocolate_o_brian

iTrader: (22)

Remove the dump valve and see if the problem persists with the OEM re-circ. If it does, take it to a specialists for further investigation. If it stops, either leave the OEM re-circ on or have your map tweeked for the VTA if you have to have it on the car.

Prodrive Brad

Cheers for the advice guys, the second opinions to make me do something about it have been worth it. Will give scoobyclinic a look as well.

Bob Rawle

The HKS SQV is the worst device you could fit on your car, and it might not even be genuine, they can and do cause all sorts of problems, suggest you replace with the OE item and then leave it at that.

But the problem you describe may also be elsewhere.

cheers

bob