eggy790

iTrader: (20)

hi all

looking at an 03 wrx, i know he's had an uprated turbo/remap 2 years ago so running just under 300 bhp

anyway the car has a hesitation. its just like a jerk when changing gear, no idea how to fix it, he's checked plug gaps and it wasn't that, he tried running it around the block without the air filter as he'd read somewhere induction kits could cause it, but that made no diff either.

Could it be Maf Sensor? and how much to replace them?

cheers

scoobiewrx555

You are looking at a WRX with an uprated turbo (which Turbo??), It has an induction kit(which one??) Have the injectors been changed?? What about exhaust system and uppipe?? Do you have a non standard Blow-off/Dump Valve that vents to atmosphere or one that is recirculating, or the standard recirculating air bypass valve bolted to the top mount intercooler.

Before you go blaming the MAF sensor accurate info on exactly what the setup is would be helpful.

P.S. A bent Lambda sensor isn't very helpful to smooth running. If that's screwed it will create some running problems.

FauxSTi

iTrader: (1)

It's my car he's looking at, I don't much about these things but I'll try to give as much info as I can...

All I know about the turbo is what the last owner told me, he said it was an RB22, or from an RB22. The induction kit is a Vector. Don't know if injectors have been changed. The exhaust is a straight through Mongoose, inc de-cat, don't know about uppipe. It has aftermarket dump valve, no idea what make, but it vents to atmosphere.

scoobiewrx555

It could well be that due to the aftermarket VTA BOV at the time of gearchange when the intercooler is being emptied pressure is vented to atmosphere instead of being recirculated back to the turbo inlet pipe, and suddenly you have a very rich AFR situation which is very likely causing the jerk and is something that will happen every time you change gear, specially on hard acceleration/WOT runs.

Also a newage WRX in that state of tune not only does it not need an aftermarket BOV due to the OEM recirc bypass valve being a very good bit of kit for +400bhp but a standard airbox with a high flowing flat panel air filter and snorkus mod is better upto +430bhp than any aftermarket induction kit. Most of these induction kits and aftermarket BOVs cause more problems than they are worth.

Change it all back to the standard airbox and oem recirc bypass valve and that will improve the drive no end. Unless you're making big power a lot of these aftermarket parts are a waste of time and money.

With a newage WRX your best mods are decat exhaust and uppipe, ported standard headers, high flow flat panel air filter, Snorkus delete mod and a bloody good remap!! On standard turbo and injectors you're looking at c.275-290bhp depending on the remap and time of year, and with a VF35 or TD05 16G and 550cc injectors you'll easily make a very solid 330 bhp and certainly a bit more than that but on a WRX engine probably 330bhp is really the limit i would take it and your gearbox to, and your max rpm's would be lowered too just to save your engine from an over zealous right foot.

HTH

scooby1doo1

iTrader: (7)

I'd also go with it been a dump valve problem, put it back to the standard 1 and I'm sure it will run more smoother.

FauxSTi

iTrader: (1)

Whats involved with changing it back to standard? Is there likely to be parts missing?

FauxSTi

iTrader: (1)

Just had a look under the bonnet and I can't find it, any idea where it would be fitted?

P.S. I noticed the turbo has H4 on it, can anyone identify it from this?

FauxSTi

iTrader: (1)

Anyone?

Kinni

What is it you can't locate?

FauxSTi

iTrader: (1)

The dump valve