In this article, we will learn about solutions for a common issue faced by Honda Civic 6th & 7th generation owners: the Idle/Throttle Body Problem.
1. Honda Civic experiencing idle due to throttle body issues
Problem: Idle/Throttle Body Problem in a 2000 Honda Civic.
The car experiences a bouncing idle on start-up and after it warms up, the idle raises from 1000rpm then stays at about 2000rpm.
When the driver takes off, something goes wrong with the throttle body, making it difficult to drive. The check engine light is on for the idle air control valve, which the driver replaced, but the light came back on. The driver is unsure if the throttle body is making it hard to drive.
Solution: Based on the description, the problem could be a vacuum leak in the throttle body or a faulty throttle position sensor (TPS). Here are some potential solutions:
- Check the IACV Connection: Ensure that everything on the Idle Air Control Valve (IACV) is connected properly. A loose connection could cause a vacuum leak, which can cause the engine to idle erratically.
- Clean the Throttle Body: Use a throttle body cleaning spray to remove any dirt, carbon buildup or debris that could be affecting the throttle body’s performance.
- Replace the Throttle Position Sensor (TPS): The TPS, located on the side of the throttle body, can become faulty over time. It can cause the engine to sputter or jerk when the gas pedal is pressed. A new TPS can fix the issue, and it can be replaced without taking the throttle body off.
After testing the TPS on the computer and discovering that it was cracked, causing a vacuum leak, the driver replaced it, and the problem was solved.
The combination of the TPS vacuum leak and the IACV was causing the issue. The driver also cleaned the throttle body, which helped to improve the performance of the car. If you experience a similar issue, try these solutions to see if they help.
2. Problem: Idle Surge in 7th Generation Civic 2001-2005
Are you having trouble with your Honda Civic’s idle bouncing? If you are, you are not alone. This issue commonly occurs after replacing the head gasket and can cause the check engine light to turn on with the error code P0505 (idle system malfunction).
Replacing the Idle Air Control valve (IAC) or other sensors such as the MAP, EGR, oxygen or throttle position sensors may not solve the problem. This was the experience of one Civic owner who spent hundreds of dollars on sensors before discovering the root cause of the issue.
Solution: The problem could be caused by a ring of paint on the back side of the butterfly plate and sides of the throttle body that is often mistaken for dirt or carbon.
This paint should not be cleaned off, as it serves to prevent too much air from entering around the throttle plate, which can cause an idle surge. If the paint has been cleaned off, here are some solutions:
- Adjust the minimum air screw to stop the surging. However, this may not work if too much paint has been removed, or the screw is rusted.
- Remove the throttle body and reapply paint around the rim of the butterfly plate, then re-adjust the minimum air screw until the engine idles. This solution should only be attempted by those who are technically capable.
- The best solution is to replace the throttle body, which can be found at a reasonable price on websites such as eBay.
Note that excessive dirt buildup around the butterfly plate can also cause a very low idle. Use only a clean rag to gently wipe off any grime buildup.
It is important to ensure that your mechanic is aware of the paint ring issue and does not spray carb cleaner in the throttle body, which can also cause an idle surge. Before spending money on sensors, try these solutions to save time and money.
3. Problem: ECU/Throttle Body Problems in 7th Generation Civic 2001-2005
If you are experiencing issues with your 2004 Honda Civic’s throttle body, such as receiving error code PO507 even after changing the valve and unplugging the fuse, you may need to reset the ECU.
A friend of mine faced a similar issue with his Chevrolet and was seeking help in resetting the ECU.
Solution: To reset the ECU, you need an OBD2 engine scanner. You can purchase one from a parts store, an online retailer or visit a mechanic or dealer for assistance. Once you have the scanner, follow these steps:
- Ensure you used a new OEM Honda IACV.
- Disconnect the negative terminal from the battery.
- Turn on the headlights and depress the brake pedal a few times to discharge residual voltage.
- Turn off all electronics in the interior.
- Reattach the negative cable to the battery.
- Start the engine and let it idle for roughly 20 minutes until the radiator fan engages twice.
It’s important to note that while this solution may work for some, it’s not a guaranteed fix. If the problem persists, you may need to consult a professional mechanic or dealer to diagnose the issue.
Additionally, using a non-OEM IACV can lead to problems with the throttle body, so it’s essential to use only new OEM Honda IACVs.
4. Problem: High idle after cleaning throttle body on 7th Generation Civic 2001-2005
After cleaning the throttle body on their 2001 Civic, the engine idles high for a few seconds when starting the car and also when braking.
You also noticed slight acceleration when releasing the brakes. They reused the old gaskets and did not properly research the cleaning process before doing it.
Solution: Whenever the throttle body is removed, an idle learn procedure must be completed, otherwise, the car will not idle properly. To fix this problem, follow the steps below:
- Start the car and warm it up to operating temperature. You can drive around to do this, but you may experience an unsteady idle.
- Park the car and turn it off. Open the hood and locate the fuse box. Remove the FI ECU fuse.
- Put the fuse back in, close the hood, and start the car. Let it idle for 10 minutes in park or neutral without using any lights/accessories or pressing the gas.
- After 10 minutes, shut the car off. Start it again and drive like you normally would. It may take up to a full tank of gas for the ECU to relearn fuel maps and readiness codes.
- The idle will be set immediately, but it may take a while for the ECU to relearn everything, and for the car to get good mileage again.
Note that when cleaning the throttle body, it is important to replace the old gaskets and complete the idle learn procedure to avoid any issues.
5. Problem: Maintenance Light Flashing After Installing New Throttle Body in 7th Generation Civic 2001-2005
Let’s assume you have recently installed a new throttle body in their 7th Generation Civic 2001-2005 and noticed that the maintenance light flashes until the car is put into drive.
You are concerned that this might be a problem and have received conflicting information, including a claim from their brother that the new throttle body could damage the intake valves.
Solution: The flashing maintenance light is not a cause for concern and typically indicates that the car needs an oil change. It is important to note that there is no evidence that the new throttle body will damage the intake valves.
The car’s idle should not be affected if the installation was done correctly. However, if the idle is higher than usual, this could indicate a vacuum leak. In such cases, it is recommended to check for a vacuum leak and fix it before driving the car.
If the idle is high and there is no vacuum leak, the electronic control unit (ECU) may need to be reset. To do this, disconnect the negative terminal from the battery and depress the brake pedal a few times to discharge residual voltage.
After reattaching the negative cable to the battery, start the engine and let it idle for 10 minutes in park or neutral without using any lights/accessories or pressing the gas. This should allow the ECU to relearn the idle and fuel maps.
If the idle issue persists, another possibility is that the ECU needs to be reprogrammed. In such cases, it is recommended to take the car to a Honda dealer or a qualified mechanic who can diagnose the problem and recommend a solution.
This article provides solutions to common idle and throttle body issues faced by 6th and 7th generation Honda Civic owners, including checking connections, cleaning the throttle body, replacing faulty sensors, and resetting the ECU. Following these solutions can save you money on expensive repairs.