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Vexing Vauxhall

By Darren Kerr
6th September, 2009

The Car: Vauxhall Vectra 2.0CD V Reg Eco Petrol Manual (although this same method could apply to many Vauxhall cars, plus maybe others using the same throotle body type or technology.

The Task: Remove, clean and replace the throttle body and idle control valve assembly

The problem: engine cutting out and idling inconsistently, especially when the weather is warmer and/or starting up after a short while when the engine is warm, i.e. park up, pop into a shop and start off again.

Rationale: the throttle body (TB) governs the flow of air that is to be mixed with the fuel, along with reduced air-flow for when the engine is not up to running temperature. Any issues with idle control are likely to stem from the TB.

Tools required: as well as trusty socket set, alan key set, assortment of screwdrivers, pliers, some old rags, lead light and ratchet hand clamps, I also bought the following…

-Gaskets for TB (2) £2 (from the Vauxhall dealer)
-Breather hose from cam/rocker cover to right side of TB £4 (from the Vauxhall dealer)
-XTend Carb. Cleaner £5 (from Kevin Coopers)

Special tool for this job (because every job needs a special tool): flexible clasp. This is a tool I have had for ages and is a flexi cable with a clasp that opens and shuts by depressing a plunger. Really useful for fetching nuts and bolts that drop into inaccessible places. For this job, I used it to undo and remove the 4 nuts that hold the TB on the manifold after they were loosened with a 10mm socket. Also, to put them back again before tightening.

All navigation is taken from looking at the engine compartment from the front of the car.

Rig up a lead light at the rear of the engine compartment for extra visibility. Not the brightest of areas to work!

So, to get going, remove the large air pipe (A) by unscrewing the 2 large jubilee clips on either end, and the smaller diameter pipe that connects to the cam/rocker cover (pliers for this hose clip). Also, unplug the 2 electrical plug connections along this pipe.

In my case, the mucky, manky TB (B) is exposed before me. Yours may look cleaner, but mine had done about 130,000 miles!

With pliers pull towards you the ball-joint of the throttle cable off of its holder (C). This should be effortless. In my case I had cruise control. There is a surclip or horseshoe clip holding the plastic terminator in place. Be very careful not to loose the clip. It isn't springy but is a bit fiddly getting the pinkies in that area.

There are 2 alan bolts holding the bracket (D) for the throttle cable(s) that need to be removed. The lower of these is hard to get at because the usual alan key is not quite long enough and the fuel pipe is in the wrong place. Perseverance is required here, or some better tools.

I have some wood-working ratchet hand clamps, like quick action G clamps, that I only needed on the top coolant pipe (E) that attaches to the right of the TB. I clamped this pipe on the left side of the TB, just out of the way from where I was working. The lower pip does not need clamping. Take both pipes off by using pliers on the hose clips. A little coolant will be lost and it may smell a bit when the engine is started later if it cannot be mopped up.

Remove the 2 breather hoses (F) from the right (half inch) and the rear (tiny) of the TB. Both will pull off and have no clips. The half inch pip to the cam/rocker cover should be removed completely and replaced if you are in any doubt of its condition. The reason will be revealed later.

There are 2 electrical plug connections to be removed. One is located on the front-left of the TB, which is the Idle Control Valve (ICV) (G). The other is at the back of the TB and I never found out what that was - doesn't matter though for this job ;-)

Now to the 4 stud nuts. Loosen the nuts with a 10mm socket. Then with the nifty clasp, grab each nut and use the clasp to undo and extract the nuts from their fairly inaccessible homes. Long nosed pliers could be used for this, taking care not to let go of the nuts as they are turned and removed.

The TB should now be free to remove by gently easing it up and back to clear the 4 studs and the other bits that are in the way. Discard the gasket on the manifold, as the replacement cost for both gaskets used in this job amount to a mere £2.

Now for the deep cleaning. On a workbench or similar, undo the 2 alan bolts that hold the ICV assembly (G) on the left of the TB. I used a mallet on the alan key to shock the initial release of the bolts. Discard the gasket, but first note its position. There is a little tag to help locate it.

There are 2 screws holding the ICV onto the chamber on which it sits. Note the position it takes in relation to the chamber. The screws initially look like posi-drive or Philips screws, but are also cross-heads. Use a cross-head driver. If you have a vice or similar, or an extra pair of hands, hold the ICV upright to get at the screws. If the slots look bad, use a small screwdriver to first clear the slots to ensure a good grip with the cross-head. Undo each screw and pull apart the ICV from its chamber. There is an o'ring that should be set to one side (can be re-used).

Set up somewhere outside with lots of rags. My big mistake was not realising the pressure behind the carb. cleaner spray. I sprayed the cleaner into the ICV chamber and so strong was the pressure, I ended up with mucky carb. dirt platted back all over me! It would also be wise to get some goggles because I couldn't help but get splashes over me, even after the first incident.

Liberally spray the cleaner all over and, with a rag, start to clean all over the carb. I sprayed a little on the ICV plunger end, but didn't want to go to town on this part because of the electrical bits. I was also mindful of whatever that electrical thing is on the back of the TB. The rest got blitzed and came up really clean.

Now the important bit. The reason why my car had the problem in the first place. Remember that breather hose that goes from the cam/rocker cover to the right of the TB? Have a look at the hose connection on the TB and then inside the TB to see how the big hole on the outside reduces to a tiny hole on the inside (under the butterfly valve). You may even miss it while cleaning as it is tiny. With a paper clip or similar, and from the inside of the TB, gently push the out-folded paper clip wire into the hole. If what you are using does not fit, do not force it. This is precision engineering. This action does not remove the dirt. It simply makes a path for the carb. cleaner to do its job. The Xtend cleaner has a directional nozzle that can be pushed up against that tiny hole from the inside of the TB. Spray outwards and notice spray coming through the hole. When the way is clear, work from the outside and push the nozzle right up to the brass connection and spray. You should get a fine and satisfying spray inside the TB.

So now you know why we should replace that half inch breather hose. Any loose bits inside it will simply bung that tiny hole back up again. For £4 replacement cost, it aint worth the argument.

Carry on cleaning all around the butterfly valve, especially at the hinge end and around its rim. Use toothpick sticks with small bits of rag. In the ICV chamber, make sure that the plunger can be depressed and its return is free. There isn't much you can do aside from that because the ICV and its chamber are fairly sealed units aside from the cleaning.

I cleaned all the outside of the TB as well, plus around the manifold. When you are happy with the cleaning, join back together the ICV and its chamber, not forgetting the o'ring. The ICV assembly can now be put back onto the side of the TB, referring to your notes on the gasket position with the new gasket. Tighten as tight as you can without sheering the alan slot.

Back into the engine compartment, ensure the manifold surface is clean and dry and place on the new gasket. Gently place the TB back onto the manifold studs. With the nifty clasp on each stud nut, start the nuts turning on the thread. Tighten the nuts lightly, then working in diagonals, tighten each nut. There are torch settings somewhere, but as a general guideline the TB doesn't need to be murder tight. Over-tighten and you risk sheering the stud bolts, which is bad news. Comfortably tight is good.

Re-connect the electrical plugs, then the 2 water pipes and remove the clamp. Bolt on the throttle bracket with the really awkward lower bolt and then replace the throttle cables. Be careful with the surclip as it is too easy to slip while pushing these clips on and loose it in the depths of the engine compartment. The main throttle cable should easily push back into position on the ball joint.

The thinnest breather hose can be taken off and cleaned through with the carb. cleaner and then repositioned. The new half inch breather hose can be fitted.

I lubricated the throttle arms and spring assembly because I had blasted off any trace of oil with the carb. clearner. Clean engine oil is good enough.

Re-fit the large air pipe and its electrical connections and side pipe that connects to the cam/rocker cover.. Wipe down any spilt fluids and ensure that everything that shouldn't be in the engine compartment is removed.

Start up the engine. Mine started first time, but it may be a little sluggish at first. Let it run without revving it. There may be a burning smell of spilt coolant and you may need to top up the coolant if too much was spilt. Take the car for a spin and let it warm up to give it a good test. All should be working well and, in my case, no more trying to juggle the brake and throttle pedals at the same time to keep the car going when slowing up to the traffic lights!

The whole job took me about 2.5 hours and cost £11. There are plenty of references on the web of garages wanting to charge clients in excess of £400 to replace the ICV or even the complete TB, plus labour and VAT. This fairly simple job will determine if the ICV needs replacing. If it does, consider a second hand one, as there isn't a great deal that can go wrong.

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