SPi Throttle Bodies (TB)

Ah yes the lowest of the low form of fuel injection - single-point injection, or 'SPi'. Still there's plenty of SPi engines about - 1.4 Clios, 19s and Meganes all have them.

The TB in this guide is a Bosch 3 bolt air filter job from a Clio 1.4, in case anyone is really interested. As usual this is really a thing you should do every 6/12 months depending on the cars usage.

As usual it's oil contamination from the engine's breathers that clog it all up aside from the Idle Stepper Motor as we shall see later.

You need:

Carb/Brake Cleaner
Toothbrush
T30, T20 and T25 Bits
Somewhere to work where bits won't get lost!

First things first, you need to remove the TB from the engine. Four T30 long bolts hold the throttle body to the manifold. Open the throttle by hand and remove the throttle cable.

This is what you should have:



Here with the Throttle open:



Now's the time to seperate the two halves of the TB. Squeeze the black plastic lugs using needle nose pliers or your fingers, and pull the top including injector off.

This is what you get:



This picture shows the underside of the injector and the black loop, while the pokey thing on the side of the injector nearest my hand is the inlet air temp sender. Also the gasket is on the top half to to right.

What you want to do is get the carb/brake cleaner and a toothbrush and get that all gleaming.

Here's the actual TB itself:



Again get busy with the carb cleaner and the toothbrush. The black plastic box thing with the red achtung sticker on it is the Idle Stepper Motor. This is what controls the idle speed.

Hold the throttle open like this and spray and clean with the toothbrush. It's fiddly but it needs doing.



That's all you need to do for a quick clean, but for those wanting to go a little further this is what you do now.....



This picture shows the top of the TB stripped right down.

On the right you have the inlet and outlet barbs for the fuel line, note that internal filters are fitted.

The lead supplies the power to the injector and also the supply signals from the air temp sender.

Up the top you have the fuel pressure regulator which consists of four screws, cover, cap, spring and diagphram. If you stick a washer under the spring you will increase fuel pressure.

The red and yellow object is the actual injector.



This picture shows the idle stepper motor removed, it's screws and the plastic tags that secure the top of the TB to the base.



This picture shows the base minus the tags and the idle stepper motor, make sure this is spotless, even using cotton buds to remove the carbon ring. The black bit on the right hand side with the plug connector is the Throttle Position Sensor (TPS).



There's a better pic of the TPS. The hose and that black round thing is a breather for the TPS chamber.

Righty, from here on is all about the idle stepper motor. This can be taken apart but the lugs can break off if your not careful. So at your own risk.



This is the two halves of the motor seperated, there is a rubber seal which is basically a black rubber band as well, and yes it's a pain to hold when putting the two halves back together.



This is the motor removed along with the worm drive, it's not broken it comes in two parts like this. Clean the manky old sticky grease from the worm using carb cleaner.



This is the gear the worm spins, this moves the plunger in and out. Again clean the old grease off and apply sparingly some new stuff.



This picture shows the top half of the stepper motor's casing. The two silver prongs supply the motors power feed (top two connectors in the plug). The spike to the left of the picture is what the gear goes over, there's metal prongs on the inside of the gear and on this spike there are two metal tracks, these go to the bottom connectors at the plug.

These vary in resistance depending on where the plunger is, this is what enables the ECU to actually control the idle speed.

Clipping the two halves backtogether is a bit of a fiddle because of the rubber seal but don't leave it off!

Stick it all back together. Ideally disconnect the battery so the ECU resets. Connect everything up and that's it. Hopefully it should now run better.