97 forester stb problem

[JND]

All right so whenever I stop at the lights or an intersection I notice the revs drop down to almost stalling point then pick back up, then drop back down then pick back up, then it slowly starts to level itself out..

Any ideas what could be wrong?

On an additional note (dont want to start a new thread) anyone know where to get lifters/tappets from? Or even know of a trick to shut them up?

Thanks

[ben-jamminn]

Try cleaning the IACV (idle air control valve)

[JND]

Do I need to take off the manifold for that? Or can I just uuscrew it? What should I use to clean it?

[MatdaymonV2]

Just unscrew it, upper engine cleaner does a good job of cleaning out the IACV.

Alternatively if that doesn\'t sort it out start looking the way of the AFM

[Darkdax55]

My old honda used to do this at the lights. Turns out i had a massive vacuum leak.

[nztintin]

My forester does that, I\'ve tried and changed a lot of things, nothing has really helped, I now call it a "feature" rather than a fault

[tebbyj]

Check for vacuum leaks by spraying brake clean or similar on hoses and listening for idle pickup. If not clean or replace air flow meter can quite commonly crap out and cause rough idle.

For the lifters go to BNT or Part master and get your self a bottle of Proma MBL8 ($50 for a small bottle) add to oil when you do the next change and it will shut those lifters up.

[Kiwi_Fozze]

are you running a BOV? that\'ll do it. or a vac leak. my 2000 forester did it as well, cleaned the IACV and it sorted it out for a few weeks, but kept coming back. try all of the above... lol

[JND]

 tebbyj said:

Check for vacuum leaks by spraying brake clean or similar on hoses and listening for idle pickup. If not clean or replace air flow meter can quite commonly crap out and cause rough idle.

For the lifters go to BNT or Part master and get your self a bottle of Proma MBL8 ($50 for a small bottle) add to oil when you do the next change and it will shut those lifters up.

Would wd40 do it? lol. Ok sweet. Yeah ive heard that stuff is the best

[JND]

 kwi_fozze said:

are you running a BOV? that\'ll do it. or a vac leak. my 2000 forester did it as well, cleaned the IACV and it sorted it out for a few weeks, but kept coming back. try all of the above... lol

I am running a bov. Would a plumb back one prevent it?

[Rosssub]

6am Super Post ;D

 JND']

Check for vacuum leaks by spraying brake clean or similar on hoses and listening for idle pickup. If not clean or replace air flow meter can quite commonly crap out and cause rough idle.

For the lifters go to BNT or Part master and get your self a bottle of Proma MBL8 ($50 for a small bottle) add to oil when you do the next change and it will shut those lifters up.

Would wd40 do it? lol. Ok sweet. Yeah ive heard that stuff is the best

No. Use an Ether based spray, Start Ya Bastard/CRC Engine Start. Things like WD40/CRC5.56 aren\'t flammable enough, so have little effect on the Engines Idle for Vac Leak testing.

are you running a BOV? that\'ll do it. or a vac leak. my 2000 forester did it as well, cleaned the IACV and it sorted it out for a few weeks, but kept coming back. try all of the above... lol

I am running a bov. Would a plumb back one prevent it?

Kwi_fozze means your Aftermarket BOV might be leaking at Idle. Try blocking it off completely and see if the problem stops.

On an additional note (dont want to start a new thread) anyone know where to get lifters/tappets from? Or even know of a trick to shut them up?

The term Tappet/Valve Lash, refers to the Gap or Space between your Cam Lobes & Valve Lifters. OEM service interval is 100,000kms so Shims/Gaps should get checked with Cam Belt Service but never do. Then start ticking between 160,000-190,000km.

To check them your Rocker Covers need to come off, to adjust them your Cams need to come out.

If you have a single tap/tick noise, that you can pin point to a certain Cylinder by ear. Then you have one Valve Lifter Shim that has worn slightly beyond Spec and could do with a slightly thicker Shim. It wont cause any damage afaik, just annoying.

I was running 5w30 Edge in my BH5 at 200,000kms, I got a Tap/Tick noise from Cylinder 3, worse when hot. I changed to 10w40 (thicker when hot) and my Ticking went away.

[quote name='JND said:

All right so whenever I stop at the lights or an intersection I notice the revs drop down to almost stalling point then pick back up, then drop back down then pick back up, then it slowly starts to level itself out.. Any ideas what could be wrong?

I would second IACV.

It\'s sticking or opening too slow during Idle, then your ECU/AFM/O2 is compensating and levelling it out.

Try disassembling your IACV completely.

Clean all mechanical parts with Carb Cleaner, (Piston/Valve/Spring)

Clean all Electrical Parts with Electrical Contact Cleaner, (Motor/Contacts/Loom Plug)

Then whip out your Multi Meter.

With Ignition on:

The ECU feed to IACV should show 3v.

The Power Feed to IACV should show 10v.

With Ignition off:

Test Ohms/Resistance between the 3rd/Last IACV wire and the Engine Block. This is the IACV\'s Earth Wire, if it shows any less than 5 Ohms your IACV has a bad earth. If it shows Infinite Resistance or Open Circuit, then your IACV has no Earth at all.

You can Find your ECU Pin for the IACV, and test Resistance between this and the IACV Plug. If it shows Less than 1ohm you have a broken wire or broken contact between the ECU and IACV.

You can then test the Resistance between your ECU Pin and Engine Block, if it shows any more than 1M Ohm you have an Earth Short.

[JND]

Super post alright lol. Cheers bro. Will start that after work

[Rosssub]

 JND said:

Super post alright lol. Cheers bro. Will start that after work

Sweet, good luck. Looking at wiring diagrams/pinouts, you might have an IACV with 4 wires not 3. Just means your ECU has 2 Signal Wires to the IACV, one to open it and one to close it. But the Resistance Tests will still show the same.

If you have a 4 wire IACV then your ECU Pins 1 & 2 on ECU Plug 137 control your IACV. ;D

http://www.brdevelopments.com/docs/MY97ecu.pdf

[Rosssub]

If that all tests ok, then it\'ll be your AFM

But at least your save a few hundred buying a new IACV that you didn\'t need. 8)

[Guest]

I couldnt remember what bov you had but most likely the issue. Ive got a v3/4 sti one you can try but you will need the plumback pipe.

[JND]

I have a cheap bov from repco lol.

I took off IACV and it seemed quite clean, but still unleashed half a can of carby cleaner into it. I then looked around and noticed the bracket for the pipe that comes off the turbo to the pod filter was broken so replaced it with one I got from evowrx (shot bro) took her for a spin and she hasn\'t ran that good since I got her!! So thanks heaps for ur info and help guys..

Now im just chasing an oil leak (which I believe I found under the throttle body) so hopefully thats fixed aswell. Only time will tell...

[Rosssub]

Sweet - Split Intake Pipe - Intake Leak messing with MAF/AFM/AFR.

Does the 97 Forester have a PCV Valve under the TB? Could be blocked, causing oil drip from Blow By/Crank Breather.

[JND]

That would explain alot. Would that be the black thing to the right of the bracket I just fixed. Because in that area is where all my oil is sitting. Or is it directly below the throttle body? Would I be able to check it (take it off) whole the engines still fairly warm or will I be rushing to the burns unit at the hospital lol

[Rosssub]

Id let it cool, especially if you still have the TB Coolant connected up? TB will be close to 80c.

Some cars have the PCV Valve mounted directly under TB, so Block Breather-Straight to TB. Others have the PCV Valve mounted in the Intake Manifold.

So it\'s either your TB mounted PCV Valve/Hose Join leaking.

Or just Blow By oil leaking through your Paper Type TB Gasket. But your TMIC was pretty clean so most likely PCV Valve. ;D

[Guest]

So it was a vac leak on pressure side it should definitely go better. Still say go stock bov recirc. If you want to try it txt me ill bring it over.

[JND]

Alright so I think my pcv valve is leaking judging by the spray patterns. On top of that, the hose coming from it connects to a plastic piece, from there it has a hose to the block, then a hose to the afm intake pipe. Well the hose that goes to the block is cracked. Which im guessing is where im getting pools of oil from

I cant find any replacements online? Are they not stocked in NZ? Ill go down to repco and see if they have any tomorrow

[Rosssub]

 JND said:

Alright so I think my pcv valve is leaking judging by the spray patterns. On top of that, the hose coming from it connects to a plastic piece, from there it has a hose to the block, then a hose to the afm intake pipe. Well the hose that goes to the block is cracked. Which im guessing is where im getting pools of oil from

I cant find any replacements online? Are they not stocked in NZ? Ill go down to repco and see if they have any tomorrow

Probably the Plastic Elbow Cracked/Split. The Plastic elbow is Brittle as hell. I doubt Repco would have one, I made my own from a broken Secondary Relief Valve. Then Changed it to a Galv Water Fitting from an Engineering shop.

Ring Subaru with your Vin/Rego and price a new one, might not be too bad?

Edit: From memory the Block Pipe is 20mm I/D.

[Rosssub]

[JND]

 Rosssub']

[quote name='JND said:

Alright so I think my pcv valve is leaking judging by the spray patterns. On top of that, the hose coming from it connects to a plastic piece, from there it has a hose to the block, then a hose to the afm intake pipe. Well the hose that goes to the block is cracked. Which im guessing is where im getting pools of oil from

I cant find any replacements online? Are they not stocked in NZ? Ill go down to repco and see if they have any tomorrow

/quote]

Probably the Plastic Elbow Cracked/Split. The Plastic elbow is Brittle as hell. I doubt Repco would have one, I made my own from a broken Secondary Relief Valve. Then Changed it to a Galv Water Fitting from an Engineering shop.

Ring Subaru with your Vin/Rego and price a new one, might not be too bad?

Edit: From memory the Block Pipe is 20mm I/D.

The block pipe was 20mm. The plastic bit seemed fine. Would have to recheck to be fine. Do you know where to get pvc valves from? I cant find any.

[Rosssub]

Repco or Supercheap should have PCV Valves. Only about $10-15 each I think?