Ava Romero
The Idle Stabilizing Valve (ISV) is an important component of Volkswagen Golf Mk2 engines. A correctly functioning ISV should drop to between 1000 and 1100 rpm when you take your foot off the gas pedal, with the needle slowly returning to a normal idle speed of about 800 rpm. If your ISV is clogged, you can clean it with an electronic parts cleaner, carb cleaner, or brake cleaner. However, it's important to note that VW used three types of ISV for the Mk2, each with different removal and installation processes. Before cleaning, it's recommended to test your ISV by turning on the ignition and listening for a humming sound, followed by feeling for a vibration.
Characteristics and Values Table for Cleaning the ISV MK2 Golf
| Characteristics | Values |
|---|---|
| What is an ISV? | Idle Stabilizing Valve |
| What does it do? | Stabilises the idle when the throttle is closed |
| How to identify a clogged ISV? | Wide rpm range oscillation (600-1400) |
| How to test if the ISV is working? | Turn ignition on, pop the hood, listen for a hum, and touch to feel vibration |
| How to clean? | Disconnect, spray with cleaner, soak, and let dry before re-installing |
| Recommended cleaners | Carb cleaner, petrol, WD40, electronic parts cleaner, starter fluid |
| Additional checks | Measure resistance (ohms) from the center pin to each side (should be ~12.5 ohms) |
| Troubleshooting | Check throttle switch contact in the off position; loosen cable if too tight |
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What You'll Learn
- Cleaning products: use carb cleaner, petrol, WD40, or electronic parts cleaner
- Soaking: leave the product to soak for a while
- Starter fluid: spray and let dry before re-installing
- Disconnecting: turn off the engine and disconnect the connector from the valve
- Testing: turn on ignition, pop the hood, and listen for a hum
Cleaning products: use carb cleaner, petrol, WD40, or electronic parts cleaner
When cleaning the ISV on a Mk2 Golf, there are a few different products you can use. One method is to use a carb cleaner. Start by spraying a generous amount of the cleaner into the valve and, if possible, let it soak for a while. You can also use petrol or WD-40 as a soak before applying the carb cleaner, as these products will disperse after use. After cleaning, operate the throttle from the manifold with your hand – open, close, open, close – and you should hear the switch clicking.
Another product that can be used is an electronic parts cleaner. This is a more specialised product that is designed to clean sensitive electronic components without causing any damage. It is important to use a cleaner that is safe for electronic use, as some cleaners can leave behind residue or cause corrosion.
Brake cleaner is also mentioned as an option, though it is not advised to use this on the electronic parts of the ISV as it may cause damage. So, if using brake cleaner, be careful to only apply it to the relevant areas.
It is worth noting that, while cleaning the ISV can help with ICV issues, there may be other underlying problems causing the engine to hunt (rev bounce). For example, a faulty throttle switch or a cable that is too tight, which leaves the throttle open. Therefore, it is important to also check these components if issues persist after cleaning.
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Soaking: leave the product to soak for a while
Soaking is an important step in cleaning the ISV of your Mk2 Golf. Before you begin, source a suitable cleaning solution. Carb cleaner is a good option, as is petrol or WD40. These liquids are effective at removing grime and will also disperse after use. Soak the ISV in your chosen cleaner. You can also use an electronic parts cleaner, which you should spray into the two holes in the valve while holding it upright so the liquid can run out.
Once you have applied the cleaning solution, it's time to let it soak. Leave the ISV to soak for a good amount of time. The exact duration may depend on the severity of the clog and the type of cleaner you are using. For example, if you are using a stronger cleaning agent, you may not need to soak it for as long. However, if you are dealing with a heavily clogged ISV, you may need to leave it to soak for a more extended period.
During the soaking process, the cleaning solution will penetrate and loosen the built-up grime and deposits inside the ISV. This process will help to soften and break down any stubborn debris, making it easier to remove. The soaking step is particularly important if you are cleaning an ISV that has not been maintained regularly or has been subjected to extended periods of use without proper cleaning.
While the ISV is soaking, you can also use this time to clean other parts of your Mk2 Golf. For example, you might want to clean the throttle switch and cable or inspect the wires connected to the ISV for any signs of damage or corrosion. By multitasking in this way, you can streamline the cleaning process and make the most of the time while the ISV soaks.
Remember, the soaking process is an essential step in ensuring a thorough clean of your Mk2 Golf's ISV. By allowing the cleaning solution to penetrate and break down built-up grime, you can help ensure that your ISV functions optimally. This step will also help extend the lifespan of the valve and maintain the overall performance of your vehicle.
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Starter fluid: spray and let dry before re-installing
Starter fluid, also known as starting fluid, is a liquid that helps internal combustion engines operate properly. It is often used to start engines that have been poorly maintained or to start older cars in cold weather. Starter fluid is highly flammable and typically comes in an aerosol spray can.
To use starter fluid to clean your ISV MK2 Golf, first check your vehicle's user guide to ensure that starter fluid is appropriate for your car. Starter fluid cannot be used with all vehicles, particularly those equipped with glow plugs or that use diesel fuel.
Once you have confirmed that starter fluid is safe to use on your car, locate your engine's air intake, which typically looks like a metal pipe and is usually found near the engine. Spray a short burst of starter fluid into the air intake, then let it dry before reinstalling the air intake.
If your engine fails to start after applying starter fluid, take your vehicle to a mechanic to examine the problem. It is important to exercise caution when using starter fluid, as it is highly flammable and can cause engine damage if not used properly. Do not place the can of starter fluid on or near a hot engine, and always store and handle it safely.
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Disconnecting: turn off the engine and disconnect the connector from the valve
To clean the ISV (Idle Stabilizing Valve) on a Mk2 Golf, you will need to disconnect the connector from the valve. Here is a step-by-step guide for this process:
Disconnecting:
- Begin by turning off the engine of your Mk2 Golf. It is important that the engine is not running during this process for safety reasons and to access the relevant components.
- Locate the ISV connector. It should be attached to the valve. The ISV is typically located near the engine and may be connected to a couple of hoses and a rubber ring.
- Once you have located the connector, carefully disconnect it from the valve. You may need to use a suitable tool to gently pry or loosen the connection if it is tight. Be careful not to damage any surrounding components or wires.
- With the connector successfully disconnected, you can now focus on cleaning the ISV. It is recommended to use an appropriate cleaning solution, such as an electronic parts cleaner or carb cleaner.
- After applying the cleaner and ensuring that the ISV is free of debris and buildup, you will need to allow it to dry completely before reassembling the connector.
It is important to note that working on automotive components can be complex and may require mechanical expertise. If you are unsure about any steps or procedures, it is always best to consult a professional or a trusted mechanic to ensure the safety and proper functioning of your vehicle.
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Testing: turn on ignition, pop the hood, and listen for a hum
To test the idle speed control valve of your Mk2 Golf, you must first turn on the ignition and let the engine run for a minute or two. This will allow the engine to reach its normal idle speed. Then, pop the hood and listen for a hum.
The idle speed control valve, or ISV, regulates the idle speed of your engine. This is controlled by the engine's computer. If the ISV is not functioning properly, it can cause the engine to idle strangely or stall.
To check if the ISV is working correctly, you should take note of the RPMs of your engine at idle speed. A common symptom of a faulty ISV is a high idle, usually above 1,000 RPMs. Low idle and sporadic stalling can also be indicators of a bad ISV.
If you suspect that your ISV is not functioning properly, you can try cleaning it. This can be done by spraying a generous amount of carb cleaner into the valve and allowing it to soak. You can also try soaking it in petrol or WD-40 and then using a carb or brake cleaner.
It is important to note that a faulty ISV may not be the only cause of high or low idle issues. Other potential causes include vacuum leaks, fuel injection assembly issues, and spark plug problems. Therefore, it is recommended to consult a mechanic or a professional if you are unsure about the source of the problem.
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Frequently asked questions
You can clean the ISV (Idle Stabilizing Valve) by spraying some electronic parts cleaner, carb cleaner, or brake cleaner into the two holes in the valve while holding it upright. You can also soak it in petrol or WD40 and then use a carb or brake cleaner. Once it is entirely clean, spray some starter fluid through it and let it dry before reinstalling.
A correctly functioning ISV should drop to between 1000 and 1100 rpm when you let your foot off the gas pedal, and the needle should slowly ease down to a normal idling speed of about 800. If your idle oscillates over a wide rpm range (600-1400), the ISV may be faulty. To test if the ISV is working, turn the ignition on without cranking the engine. Pop the hood and you should be able to hear the ISV humming slightly. Touch it and you should feel a vibration.
VW has used three types of ISV for the Mk2 Golf. The first version was a small valve that either opened or closed, added to the CIS basic engine management system. The second version was an adjustable valve controlled by the ECU. The third version uses a bigger valve and a more complex ECU that controls the idle completely and cannot be removed.
