Clean Idle Air Control Valve (IACV)

Started by Slice, October 3, 2016, 08:27

0 Members and 1 Guest are viewing this topic.

Slice

The Valve itself is mounted to the back of the throttle body as you look from behind the engine cover, it's not too tricky to extract. I'll try and recall all the steps I took. If you want, extraction without taking the throttle off is possible, but if I did it again I'd still do it this way.

Before you start, I'd suggest picking up some bent nose pliers, a 5 point torx T20 tool, and some JIS screwdriver bits.

- First, unhook the battery, safety first and all.
- Then unclip the hoses and connector to the purge valve mounted to the intake duct, or pull the bracket out of it's little slot in the duct (I couldn't without ruining it)
- Release the hose clips on each end of the intake pipe. Compressing the pleats, push the duct off the MAF housing, then twist and pull it off the throttle body. Extracting it is tricky because of the resonator on the side of it, but a bit of turning and wrangling does it.
- Remove the breather hose from the top of the throttle body that disappears under the plastic engine cover, it's held with a wire hose clip.
- Using 2 12mm spanners, and being very dextrous, release the throttle cable from the clamp, and pull the cable nipple from the hole in the quadrant. If you can't do this, don't worry, you can do it  once the body is off.
- Unclip the throttle position sensor on the side of the throttle body facing you.
- If you can reach it, unclip the connector on the IACV solenoid. This is another thing that can be done after removal of the body if needed.
- If you can get to them, release the hose clips on the 2 small bore coolant hoses on the throttle body, below the TPS. The clips may not be easy to access, I had to use bent snipe nose pliers. If you struggle, again this can be done when the body is off, and you can rotate it to access the clips.
- Pull the hoses off the body, and stuff a couple of M8 bolts into the ends of them to prevent too much coolant leaking out. You can clamp the hose clips over them if they're weeping.
- The throttle body is held to the manifold with 2 bolts and 2 nuts, all 12mm AF. They're snug and access isn't massively clean, so be cautious to not round them off.
- Slide the body off the studs and unclip anything you couldn't access.

- Flip the body over and you'll find a small aluminium casting with a black solenoid screwed into it on the back of the body, this is where you're aiming for.
- If you have a vice with soft jaws, clamp it in. Otherwise, drill a couple of holes in a plank of wood, and bolt it to it for bracing.
- The valve is held to the body with 3 screws, these are not Philips screws, they're JIS head screws. Using a Philips is possible, but you need to be very very careful as the flank forms are different and Philips screwdrivers round off JIS heads for fun. This isn't helped by the screws being 10+ years hold and pretty snug in there. I used a ratchet handle with a powerdrive adaptor and a JIS bit and I still had to lean on the head with pressure as I broke it off.
- The valve has a rubber gasket on the body, be careful not to soak this with petrol or brake cleaner, it swells and is a pain to refit.
- The solenoid is held to the valve with 2 T20 5 point torx screws. Before releasing them, mark the position of the solenoid on the body as it's rotationally adjustable.
- Unfasten the screws, pull the solenoid off and make sure you don't lose the O ring.

- Now, you'll have a valve with a little shaft on bearings in it. It should spin freely and continuously, but it may be full of soot and muck and be seized, or stiff. Get at it with brake cleaner, carb cleaner, or whatever you have. Toothbrushes, earbuds, the lot.
- Be careful not to drop it, or lever against the cylinder on the end of the shaft, it's a rare earth magnet and is brittle, so will fracture easily.
- Once it's spinning, I applied a little machine oil to the shaft and bearings and allowed it to soak in a little. I'm not sure if it was necessary, but it felt prudent to do so, and seemed to have no ill effects.
- The entry and exit ports and throttle body can be cleaned too, it probably has a mist of oil and muck in there from the breather outlet.
- Between the body and the manifold is a hex-mesh flame arrestor. I gave this a clean-off too, and put a smear of Vaseline on the gasket behind it.

- Reassembly time, all fairly straightforward once you've unhooked everything. The shaft doesn't need to be in a specific location when the solenoid is fitted, the magnet in the solenoid will pull it to the null position to start with. Remember to fit the O ring as the solenoid goes on.
- Take care re-tightening the JIS screws, and refit things like the coolant hoses as you see fit, depending on your ease of access. The hoses should be shaped to make it easy to figure out which spigot to fit them too, but if you fit them backward it makes no difference as it's just a small heating circuit to prevent icing.
- Take the opportunity to adjust the throttle cable too, if you want to.


Good luck.

shnazzle

#1
I just typed all this up without looking whether this existed fist... So I'm pasting it in here out of pure recalcitrance


There is a how to in text written by Slice.
It's definitely something I can recommend doing but I wouldn't say it's a novice job.
You need to be comfortable and familiar with working in tight areas. Know when to use what tools and how, which things to watch out for etc etc.

I'd say use common sense.

Remove battery
- 10mm spanner for poles, neg first, then Pos
- deep 10mm socket or spanner for bracket. Undo until you can unhook the bracket from the bottom
- lift battery out. Watch your back oldies!

Remove intake
- undo clip that connects intake pipe to airbox and squeeze off the pipe (tight fit)
- pull blue VSV actuator from bracket on intake
- undo clip from intake pipe to throttle body.
- remove pipe

Remove TB
- Unplug connector in front for throttle position sensor
- Unplug connector (by feel) for the IACV actuator at the bottom rear of the TB. It pulls towards the firewall
- undo throttle cable from bracket by reaching in with your left hand and turning the bracket to the left, this slacken the cable. With right hand, pull the table right so that it points up then push towards the firewlal for the ball at the end to slip through the eye
- clamp two coolant hoses that go into the IACV at the bottom. It's fiddly. Clamp the right short hose with small vice grips. Then undo the left hose and quickly put your finger on the end to stop coolant flooding out. Shove an M8 bolt or something that size in the hole so it's a tight blockage. Then remove the clamped hose from the TB.
- undo 2 bolts (12mm) from the top of the throttle body and 2 nuts (12mm) from the bottom. Don't drop them!
- slide the TB off the top bolts and turn the unit towards you so that you're looking at the top of the TB. You will see two 10mm bolts holding the throttle cable bracket to the TB. Remove them.
- slide TB out

Remove components
- remove the throttle position sensor (two crosshead screws... Be careful. Must be a perfect fit. They are soft metal bolts and can be stuck.
- using Tippex or a black marker, draw/paint around the edges of the IACV actuator on the TB so you can put it back EXACTLY where it was. I mean exact.
- remove IACV from TB by removing 3 crosshead screws.. These will be a pain. Get the best fitting bit you can find and take your time. In the worse case, you'll round one odd and need to dremel a slot and tackle with a big flathead screwdriver
- remove IACV actuator from IACV by undoing 2 5-point t20 security bolts. These are very specific. You'll have to order a set. Most torx bits are 6-point.

Clean and prep
- with lots of carb cleaner and scrubbing, clean the throttle body and the IACV until it turns freely. It can be pretty stuck.
- use spray silicon grease to grease up the bearing of the IACV
- use a new gasket between IACV and TB,from Toyota. They're cheap.

Reassemble. Enjoy.
...neutiquam erro.

Tags: