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10.5 - Cleaning the throttle body and setting the idle sp ( Martin Briscoe,  )

Fig. 1

Fig. 2

Fig. 3

Why do this?

Main reason is a sticking throttle but owners also report that the body can get very gunged up and giving it a good clean aids smoothness and performance.
How to do it

A partial job is possible by removing the intake hose, opening the throttle and wiping it out that way. However, it's pretty easy to remove the whole body and you can then do a proper job and hold it the right way (which is upside down) up to stop nasty solvents getting to the Throttle Position Sensor which it wont like at all.
Tools and materials

* At least a 75mm extension and universal for your socket drive.
* Some people add gasket material such as high temp Locktite behind the body.
* 7/32 allen wrench to adjust idle speed

Model : Pictures relate to a UK '92 3.2


Taking off the throttle is a fairly simple job. You don't NEED to take off the coolant hoses to do the job. It may make it a little easier, but not much.

see Fig. 1 :

To gain clearance undo clip (1) & (2) and pull off connector (3).

Move this pipe to the side see (6) fig. 2. to gain more access.

Loosen the clip (4) and remove this pipe from the elbow.

Slip the two electrical connectors and the relay (e) from their clips.

Then undo the 2 bolts (5) which hold the elbow to the car.

see Fig. 2 :

Undo the clip (7) securing the bellows to the throttle housing.

Do the same for the other clip (8) securing the elbow to the air intake.

The elbow and bellows can now be removed from the car. This enables visual inspection of the throttle plate. Mine was very clean so I didn't take the throttle body from the manifold.

The throttle body can be removed by unclipping all the cables and electrical connectors and undoing the 4 bolts attaching it to the air intake (Some of these are not easy to get at, a universal joint extension helps).

The plastic elbow & the bellows can get quite messy and need a good cleaning. Carb cleaner is recommended but WARNING keep it away from the MAF on the air intake and the TPS at the base of the throttle body as you could damage these sensitive components.

Check the gap between the butterfly and the Throttle body wall to make sure its .002"

While it's out, make sure you de-coke the EGR return line where it enters the throttle body, and check to see if the EGR hoses need cleaning.

Some people use a gasket material between the throttle body and the manifold.

Torque the bolts (14lb ft) after replacing. If you're using a "gauge" type torque wrench, best look at a longer extension..... one of the bottom is a real challenge to try to meet a torque spec with a large wrench.

Also be careful not to overtighten the clip sealing the bellows to the elbow. When I took mine off the plastic elbow here was squashed allowing lots of air in (see Fig 3). A new elbow is 30 UKP so I heated the kink with a hot air gun and used a curved wood former to push it back into place.

Calibration : As long as you don't move the TPS beneath the Throttle body, You shouldnt see any changes in base idle speed. If you're having any rough or irratic idle problems, then go through the motions of setting the TPS voltage, which is described in Haynes then do the Idle adjustment (see below)


sepbar.jpg (3094 bytes)

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