HI Guys,
Drove one morning, noticed the revs were dropping making the car want to stall, came to a junction and the car is revving up and down, between 500 to 1000rpm. no CEL. i had this issue a while back (2 years ago), and found out it was the idle control valve, So i assumed this would be the same issue as a ICP idle control valve was fitted. Found another one in my bucket of spares, thought id test it to see if it is that, cleaned it put it in, fired it up, car was missing and backfiring on the drive way, but then the CEL came on. Put the ICP back in and CEL was still on but i think i forced the CEL to come on with changing it from the old one i had in the bucket. Anyway, i cant afford a OEM one, so hunting for a spare. code 24 coming up using the under the connectors. My question. is it deffo a idle control valve fault, should i gamble on ICP one again..

 

Have you set the icv up correctly and if its a V5/6 I would check your MAF first.

 

As above , sounding a bit maf ish issue , I cleaned mine in the end , it worked for a short while then played up again but cleaning it and it working better for a while pointed me in the right direction of the fault , new maf put on problem solved 👍

 

Update.
I cleaned the MAF, i also unplugged the MAF whilst the car was on, and it did have a slight struggle but when plugged back in, it went back to the normal missing and running rough issue. Noticed also that my forge DV, the sleeve inside doesn't open and close properly. it gets jammed, and sometimes on start up it stays open throwing out loads of hissing air sound. I have ordered a new gasket for it. So hopefully that should sort it?..

I also disconnected the BAT to reset the ECU but no luck.

Waiting for new gasket....
Is there any other way to check the MAF is finished

 

Air leak could be part of the issue , the mafs other than checking voltage im not aware of much that can be done , mine never showed a Cel , the good news is the classic mafs used to be a fairly cheap part , the new age were the expensive one , my maf symptoms were rough idle and or stalling and hesitant running , sometimes more power most of the time less , there were quite a common failure part 👍

 

Do you think it’s worth changing the MAF? They are pretty expensive? I can see replacements from ICP from Ł100 plus?

Cheers

 

Leaking MAF will be the problem icv trying to compensate for the leak.
Meant the DV

 

That’s actually a good shout. Never thought of it like that, BUT would that still throw a code 24 if the MAF is knackered?

Okay, next question - should I buy a OEM one or get a used OEM one, or are the copy parts sufficient enough?

 

Me buy new oe one , the last a long time , it's like 02 sensors , oe branded is what I would do

 

I had similar issue when i swapped bov for forge recirculating one. No idea how but it looks like bov made issues to icv. I put back forge atmospheric bov and cleaned icv but to clean it correctly You need to take off two 5 star screws-thats on newage not sure what screws they used on classic impreza.
Those pistons in forge bov needs some lube,worth to have a look if its still there.

 

Thank you soo much. The forge BOV, it 100% needs opening up and lubed. Can i just use WD40 on it? The sleeve inside is still half shut, as you can see through the side of it. I would assume this is causing the issue? But at the same time i have a new gasket coming for it to as i have been told they thin out over time..

I will try these things first and see if the car makes any difference, if not, i have to get a OEM ICV and suspect the MAF...

This is the BOV i have Scoobyworld - Forge Motorsport VTA Dump Valve Blow Off Valve Subaru Impr... and its where the holes are going all around where the sleeve doesn't shut properly..

 

Yes atmospheric like i have now,wd40 is a cleaner ,it vaporise, You can use it on icv to clean 2 bearings and to clean forge piston and inside bov.
To lube bov piston You need pink/red silicone grease i think.

 

Many thanks for that. So looking at this, it looks like i need to undo the screws and it pops out with a spring and piston.
I can give that a good clean today and see what happens, i dont have the grease but il try reserve that, if not il have to buy it and see how i get on. but looking from the outside it seems pretty dirty so i can imagine what its like inside. This could be the cause of my ICV acting up when there is actually nothing wrong with it.

 

If you cut a piece of tin to same shape as bov flange and then slot that in between bov and intercooler you can test if the car runs better as it just deletes the bov recirc path. Doesn't cause any damage either doing so. But allows you to diagnose if it is the bov at fault

 

Thanks for that. Il give it a try. Does anyone know what oil to use on a forge BOV? Google says any low viscosity oil? Turnosmart recommend even sewing machine oil.

 

use this -Red "N" Tacky #2 grease
6-8 quid on ebay etc

 

red silicone grease is what forge supply

 

Appreciate the comments guys. I’ve managed to source mobile 1 grease which forge also recommend and its red to.

im hoping once I have cleaned this, I disconnect the battery let the ecu reset and start up again, my issue of mid firing has gone. The idles are settled but can settle more. This issue must be due to the blow off valve

 

Update:

opened BOV and idle spring broken! Cause of my issue? New one ordered

 

that would make sense then. dont think ive ever seen a broken spring in a bov before

 

Forge ones are fairly common, but they always did a "free" service kit back in the day.........

 

So they do sell a service kit but that’s Ł15. However the service kit comes with o rings and the main spring not the idle spring (that’s what they call it) so I had to get that as a stand alone item but my o rings looked fine. It’s all out and cleaned ready for new grease and spring when it arrives along with a new gasket.

il update you in a few days

 

idle spring? they usually only come with one spring fitted which is usually the yellow variant suitable.

https://www.forgemotorsport.co.uk/Va...duct--826.html

just needs to be strong enough to stay shut under vacuum and weak enough to open when coming off pedal/boost

 

the one You have is not dual piston ,You can put 2 springs depends from psi You are after.
Usually blue /yellow is enough
I put red on mine forge bov.

 

I’m not sure why mine has to. I don’t know enough about the BOV to be honest. I opened it and sent pictures to forge and they told me what spring I needed. But I have 2. Ones short spring and ones the coloured spring.

Thought it would have come in the post today but nothing. So fingers crossed it comes tomorrow and my car is running back to normal. Will keep you updated

 

Could You post some pictures here with bov open and springs?
Mine has one spring but it doesn't open when i rev it when stationery ,it does only when driving off boost like it should.

 

there is a small spring on the other side of the piston which preloads the valve...........all of the ones we have ever stripped / repaired have springs on both sides

 

Here’s pictures of my bov open and you’ll be able to see the short spring which is broken.

 

exactly as it should be......

 

NO luck guys
spring changed, lubed the dump valve. super clean, only positive that has come out of this is that the its not missing now when revving but now on idle its just going up and down, up and down. I looped in FB tuning. Amazing. i have got a ICP idle control valve, his bet is on the idle control valve. he seems to think put an oem one in..