The AUSubaru.com.au Forums

Hey everyone,

I am having this issue with my '93 WRX. The car would normally rev up to about 2,000 on startup. That's normal, after a few seconds it would drop to about 1,000. But in the last couple days when the weather has been cold and wet the car would continue to rev at about 2,000 - 2,500. Even when you rev the engine yourself, the rpm would drop back to about 2,000. I found a temporary fix for this, by opening the bonnet and revving the engine from the "main accelerator" near the manifold. Sometimes one or two revs from here would fix the problem but on occasion (when it has been raining a lot) you would have to rev multiple times. You have to almost redline the engine to get the rpm to 1,000 again. I have heard form my dad that this is cause by the "accelerator cable" sticking.

Anyone have any idea what's going on?

Sounds like a idle control unit of sorts sticking, allowing air to continue to bypass the throttle for cold start/choke fast speed function - witre off, bad contact, unit gunked up internally after 20 years ...WRX 20 years ago ?? Must be getting old

If you can find a unit that looks like it bypasses metered/filtered intake air past throttle body, try disconnecting wires when car is warm. See if it still does it next cold start, can be a bitch to start without it, so then if so, try connect it again to see if it starts.....gotta try something ???

Could be a sticky cable too

Check if the throttle stopper is making contact when closed. This will tell you if the cable is at fault. If its not, its most likely iacv (idle.air control valve) located on the passenger rear intake runner. Take it off and give it a clean with carby cleaner. There are 2 mechanisms in the iacv. The electrical servo on the top and the bimetal water gallery on the bottom. They both control a pair of vanes in the middle to control the flow of air.
DON'T undo the 2 screws on the top where the cream coloured cap is as this fine tunes the idle and is a pita to readjust if you move it.

Sent from my new touchy phone thingy

Mine used to have a sticky cable that caused this, the best cure was to undo the clips (one near the air intake and one on the fan shroud)

You could try undoing the cable at the throttle body and pouring some thin oil down it too if it turns out to be the problem.

Thanks, I will try your suggestions tomorrow. For now I think I have found another temporary fix. Before I start the engine, I open the bonnet and rotate the throttle to the max a couple times. I then start the engine and it idles correctly. I have only tried this method a couple times though. I will see if it idles correctly tomorrow morning in the cold.

Try spraying some 'silicone lube' down the throttle cable and also over the throttle body around where the rerturn spring is. Also make sure the cable has a little bit of slack in it when the throttle is in the closed position. Also check that the end that fits to the accelerator pedal hasn't come off/loose.

So another problem occurred when I drove in the morning yesterday. I would be driving normally then I would feel extra power going into the engine without me accelerating (this is after the rpm has dropped to normal). I put the car into neutral and the car would rev up to 2,000 then drop back to 1,000, rev up, drop, rev up, drop, repetitively. I pulled the car over and turned the engine off. I then did a couple full throttles in the engine bay. I started driving again and 30 seconds later it did it again... As I was pulling into another side street, as the rpm drops to 1000, it kept dropping to the point that the car just turned off. The rpm dropped so low that the car couldn't stay on. This has only happened once though.

Usually I accelerate a little while turning the car on but recently found out from a family friend that you shouldn't do that with newer cars as you may confuse the ECU as to how fuel to pump in while turning on. Is this correct?

Gannon, the throttle stopper is making contact, it always has. So I'm thinking that the accelerator cable is not at fault. When the car is revving high abnormally, I can't "de-accelerate" any further on the throttle, it's at it's lowest point.

My dad thinks it could be the carburetor. When the engine is cold, the car "chokes" a little when you throttle quickly. Even when the engine is very warm, there is a small delay in power response.

Sounds more and more like the IACV is faulty, or you have a leak in the intake manifold.

TOONGA

Tomi wrote:Usually I accelerate a little while turning the car on but recently found out from a family friend that you shouldn't do that with newer cars as you may confuse the ECU as to how fuel to pump in while turning on. Is this correct?

Not required on cars that run on an ECU, as this will add the required fuel as soon as the engine starts.

Tomi wrote:My dad thinks it could be the carburetor. When the engine is cold, the car "chokes" a little when you throttle quickly. Even when the engine is very warm, there is a small delay in power response.

Your car doesn't have a carburetor, it's Multi Point Fuel Injected, so it only has a Throttle Body to control the Air Flow.

Like Julian (TOONGA) has mentioned, you may need to have the Idle Air Control Valve cleaned/serviced. Also may need to put a can of Upper Cylinder Cleaner through it.

The car hasn't been revving up too much recently since I started to leave the accelerator when turning the car on. It may be because of the weather as well. I am getting the car serviced soon, would they be able to fix the problem?

Off topic, but does anyone know what the PSI of my WRX turbo should be at? When accelerating heavily, the PSI gauge goes up to 5 PSI relatively quickly and stays there, doesn't go any higher.

Running wastegate pressure by the sounds of it, it should be around 10psi. My guess is your boost solenoid is faulty or you restrictor pill is missing.

Can you upload a photo of the hoses that run from the top of the aluminium turbo outlet to the boost controller back to the wastegate actuator on the top of the turbo

Okay I will take a photo tomorrow in the daylight. As soon as I take my foot off the accelerator, the PSI jumps to about 10 for a split second the flutters down to 0.

Sounds like the boost gauge is hooked up before the throttle.

Gannon wrote:restrictor pill is missing

My thoughts exactly when you have low boost

Gannon wrote:Sounds like the boost gauge is hooked up before the throttle.

Does sound like it

I was able to take a quick photo is this "controller" near the turbo. I remember the last owner saying it had something to do with the turbo.

[ATTACH]4028[/ATTACH]

Ah thats a manual boost controller. Where does that pipe go from the left side of that y splitter?

Definitely a MBC and looking at it, it appears it's wound most of the way out. I'd say your best to get a Electronic Boost Controller (or put back to standard) and have it turned correctly.

The tube traveling left of the y-splitter enters the top of this little cylinder shape thing. The tube coming out the bottom of the cylinder travels to a dead end and the tube coming out the bottom right travels to the manifold.
[ATTACH]4029[/ATTACH]

When I looked at the boost controller this morning, I noticed that the screw/bolt is not there. It must have fallen off while driving or in the engine bay somewhere because I can't find it on the ground anywhere. The screw must have been at it's limit and a small vibration would have loosened it off. Is this dangerous?
[ATTACH]4030[/ATTACH]

It can be very bad as you'll end up putting too much boost into the engine, thus increasing the chances of blowing it up. I'd go up to Japanese Wholesale and talk to Fats and ask him if he has the stuff to take it all back to standard.

You can start from there and do mods but as long as you have a reference point, you know what you can go back to if things don't work.

Could I easily just cover the hole up? Or use another screw/bolt? I have noticed that the boost gauge is not working but the turbo still is.