What is a throttle plate? This is the mechanism of the intake system, which is responsible for supplying air to form a fuel-air mixture. Most budget cars are equipped with a rudimentary mechanically operated choke. We will not talk about electronic flaps, to understand the intricacies of which is quite difficult, and with your own hands they can only be broken finally. We are talking about an elementary device, which can be seen more often by removing the air filter housing.
However, sometimes the filter is on the side, then the throttle will have to look somewhere between it and the intake manifold. But if you do not find it there, then either your car is carbureted, or you should not read further, and it is better to get together and go to the car service. Especially if the symptoms indicating the need for cleaning are present.
The most characteristic of them – it is unstable work at idle speeds and periodic “hanging” of revolutions after releasing the gas pedal. Do not forget that not always the cause of “rampant” idle speeds lies in the throttle, the matter may be in other elements of the fuel system or ignition. Still, the cleanliness of the throttle plays a very significant role in the operation of the power unit.
How does the condition of the throttle plate affect the idle speed? The fact is that there are usually two devices on the choke – the throttle position sensor (DPDZ) and the idle speed regulator (RCH), which is often also called a sensor. These mechanisms not only allow you to “give gas” when you press the appropriate pedal, but also help to maintain optimal shaft speed depending, for example, on the load on the on-board network. I say exactly “help”, because if you unscrew, say, the GUR sensor, then when you turn the steering wheel, the idle speed will still jump, even if the throttle and idle regulator work perfectly. Electronics, you can’t get away from it.
Why does the choke have to be cleaned periodically?
The matter is that the air entering it is far from laboratory sterility. There are solid suspended particles and dust in it – everything that is not kept by the air filter (which we always change in time, don’t we?) All this dust is pulled inside the engine by the rarefaction in the intake manifold, but not everything gets there, a part of this stuff settles on the throttle body and directly on its flap. This is helped by oil suspension, which remains on the walls of the mechanism.
Where does it come from? The thing is that the throttle goes to the pipe coming out of the valve box cover. And just there a small concentration of oil mist is always there. If the motor is already “tired”, and in addition – well (for example, piston rings are worn out), then the oil particles will always be more, and therefore, and contamination of the throttle plate will be more active. In neglected cases, the flap will so form a dust deposit, settled on the oil film, that the mechanism may periodically “stick”. And more often the cause of the malfunction will be just in the idle speed regulator, which is installed on the throttle body. And here the cleaning of the device will be almost inevitable.
We all understand that in some services there are not very decent people (not in all, of course), who do not really want to work. And then they manage to clean the choke without removing it at all. Or – which happens more often – they do not touch the idle speed regulator, so the work is actually done, but the problem remains. Therefore, we will show you how to do it correctly, and let it be a little longer, a little more complicated, but it will provide a good result.
To work, we need a minimum set of tools and materials (a screwdriver, a pair of wrenches, a brush and an ordinary cleaner, which can be bought in any store), as well as star heads. The latter is needed only because for the example we took the engine K7M, known to admirers of wonderful cars Renault Logan. This motor is simple, its design does not contain any original solutions, so looking at how we clean the flap of this unit, you can learn to do it on any other budget motor. So, let’s start disassembly.
The main thing is accuracy!
First of all, the air pipe is removed. Everyone can cope with it. Then unscrew the air filter housing. We remove it as a whole, the element itself does not need to be taken out (unless you decide to change it at the same time). At the same time check the condition of rubber seals, through which the housing is attached to the motor. The backlash itself is not so terrible, but good tightening guarantees the exclusion of air sucking into the throttle flap besides the air filter, and the rattle of the filter housing is also not the most pleasant thing in the world. After unscrewing the bolts, we lift the case a little and disconnect the pipe from the bottom, then remove the filter case to the side. The throttle plate appears right in front of us.
On the choke we see a mechanical rod that connects the choke itself with the throttle cable through the rocker sector. It must be removed. There is no force and fanaticism: we slightly pick it up and pull it aside, after which it comes off the lug by itself. Now we disconnect the choke position sensor and idle speed regulator. Everything is simple: we unclip the connectors and remove them from the sensors. If you do not get it right away, look for the direction in which you need to push and pull, excessive force is also unnecessary.
In general, all today’s work requires more accuracy than physical preparation. Now we bow our heads and look at the base of the throttle plate. And we see there a fixing bracket, which we immediately remove. Now you can pull out the choke itself.
Before washing the assembly, do not forget to close the hole in the intake manifold, you can ordinary clean cloth or napkin: the dust that gets there will not be good for the motor.
Now it’s time to dig the throttle a little bit. It is necessary to remove the idle speed regulator. To do this, unscrew two screws and pull it out of the throttle body. The regulator is usually covered in deposits.
You can clean it with anything you want, even with a brush and carburetor cleaner. Just do not forget that there is also a rubber ring under the idle speed regulator, which should not be lost or soaked in gasoline or solvent, so as not to destroy it.
Perfectionists clean the choke to a mirror shine. Please, no one will not prohibit this. But there is no point in acting fanatically: from the outside it will still be in dust. Our first priority is to clean it from the inside. We achieve that there was no trace in the place of contact between the flap and its body, as soon as this edge leaves, the work is considered finished.
After cleaning, the entire slide should be dried. It is possible to just leave it lying there, but we use compressed air: it is faster that way. But if you don’t hurry, while the choke is drying, you can deal with the idle speed regulator. Here we are primarily concerned with the rod: it must be absolutely clean.
By the way, when washing the damper, do not forget to clean the well under the regulator well, if there will be a deposit there, the efficiency of work will be very low.
After all the operations done, the work is considered finished. More precisely, its dirty part. It’s time to take on a more pleasant, cleaner part of it – the assembly.
Oiling and take your time
If we managed to disassemble the assembly, it will be easy to assemble it. We put the idle speed regulator in place and return the flap to the place from where we took it out (it should get into the groove, screw the bracket fixing it. Before installing the rod it is desirable to lubricate the lugs with any grease, at least lithol. Put the rod and check its movement by hand: nothing should interfere with it, there should be no “snagging” or jerks. Put on the ventilation pipe (from the bottom of the air filter housing, the one we removed at the beginning of the work), tighten the bolts of the housing. Last put on the air pipe.
It is time to start the engine. In rare cases, after the first start the rpm may slightly rise. If this happens, turn off the engine and start it again. After a few attempts, everything should return to normal.
But if you have not just cleaned the choke, but changed the idle speed regulator, such a circus with revolutions is almost inevitable: the regulator does not immediately enter the working position. In its essence, it is a stepper electric motor with a valve, and at each start it adapts. This is quite a normal situation and there is no need to be afraid of it.
But it is necessary to remember that in some services this work is done differently: they remove the air filter housing, wipe the upper part of the flap with a rag and put the filter back. it looks clean, but in fact – not.
Do not look for those who undertake this work too cheaply – most likely, they will do badly, although it is quite realistic to manage in 30-40 minutes on your own. However, this applies to many other procedures, which we will tell you about.
Finally, the last question: how often should I clean the flap? Here everything is individual: if instead of blood flows gasoline, and there is a desire to “roll” even in spite of 1,5-liter motor with 80 “horses”, you will have to clean it more often (for 40-50 thousand you can dirty it completely: more revolutions – more oil dust). If not to rage on the road, then it is worth to look at the flap to a thousand to a hundred mileage. But if the engine is not in the best technical condition, the choke will be dirty until you repair the cylinder.