I bought a blob wrx standard with a ss back box, and a cheap bov fitted. It idled like a spanner, and sometimes cut out when coming to a junction and depressing clutch.
I replaced the idle control valve with no effect. then i changed the bov for a standard recirc, Result! idled perfect.
But it still sometimes cuts out at junctions, A lot less but still there, Revs drop too low and it dies, or jump back up and idles perfect?

Any ideas what could be causing this?

Thanks

 

could be a maf sensor or an air leak somewhere. do you have a diagnostic cable at all?

Get your head under the bonnet and check the rest of the vac lines, small leaks will have more impact on idle but may go unnoticed at higher RPM's where the % loss is much much smaller.

 

It idles ok since i took the ****ty bov off. admittedly a bit low at 500rpm. when driving then press clutch the revs drop low them come back up to 500, or dies.

How many vac lines are there? one to top of re-circ, a couple to boost control valve?

Cheers

PS: I don't have cable. But cel light doesn't come on so would it show any faults?

 

You don't always get a cel unless it's completely failed.

Vac lines - there are a few take offs on the manifold as well. Basically anything after the maf could be skewing the readings. Maybe even a leak at one of the intercooler pipes maybe underneath? I know when I picked up my wrx the passenger side pipe was leaking as it had black marks of dirt n such all stuck around it and the other side was quite clean.


The car will try and make adjustments for a an air leak - but the powers are limited - you wouldn't notice say 5grams of air when your flat out pulling 200grams of air in, but when trying to idle at 10/25 grams of air it's a much bigger difference.

could be something else as well, what all else have you looked at?

 

First i tried cleaning the icv. looked like it had been messed with before so i chucked one on from matty.

When that made no difference to idle, i tried a maf from my dads wrx (same year)
Again no difference to idle.

i then took off the cheap ebay bov and put on a standard re-circ, Thought this had cured it as it now idles perfect.

But still dies sometimes at junctions.

Guess it could still be the maf as when i tried my dads it was only to see if it made it idle any better, as i thought it was linked with the stalling.

 

could be maf or could still be air leak. Check the pipes leading to the turbo intake pipe - maybe the one from teh dumpvalve if its frazzled a bit from age? The intake pipes can split too usually liking to do it underneath where you can't see. Spray some maf cleaner in the area and listen to hear if the engine note changes.

 

If it's got a smooth tick over but low idle and the icv looks like it's being messed with then it might need adjusting to up the idle?

 

I changed the icv after i noticed it had been messed with. still idles at 500 with the new icv on?

 

Sounds like similar symptoms to a failing/failed neutral position switch.

 

May be worth checking the condition of the throttle body as if it's dirty and gummed up it won't help the problem