Changan Throttle Relearn Procedure: A Comprehensive Guide
If you’ve recently replaced the electronic throttle body on your Changan vehicle, you may notice poor or erratic idle afterwards. This is because the powertrain control module (PCM) needs to relearn the throttle blade angle settings after installation of a new throttle body. Performing a throttle relearn procedure will allow the PCM to properly adjust to the new throttle body so your engine idles smoothly. This guide provides a detailed walkthrough of the Changan throttle relearn process, including the specific Changan models it applies to.
What is a Throttle Relearn and Why is it Needed?
The electronic throttle body controls airflow into the engine using a throttle blade that opens and closes. Over time, the PCM makes incremental adjustments to the throttle blade angle to compensate for factors like carbon buildup.
When you install a new, clean throttle body, the learned settings no longer match. The PCM is still operating as if the original throttle body is installed, leading to incorrect air-fuel mixture and poor idle quality. A throttle relearn procedure allows the PCM to recalibrate itself to the new throttle body.
Changan Models Requiring a Throttle Relearn
The throttle relearn procedure outlined in this guide applies to the following Changan models equipped with an electronic throttle body:
- Changan CS35
- Changan CS55
- Changan CS75
- Changan CS85
- Changan CS95
- Changan Eado
- Changan Raeton
If you have a different Changan model not listed here, consult your owner’s manual or a Changan dealer to confirm the proper relearn steps for your specific vehicle.
Tools and Materials Needed
To perform the Changan throttle relearn, you will need:
- A safe, level surface to park your vehicle
- Your vehicle key
No special tools or a scan tool are required. The relearn can be done with just the ignition key.
Step-by-Step Changan Throttle Relearn Tutorial
Follow these steps to complete the throttle relearn on your Changan vehicle:
- Park your vehicle on a level surface and set the parking brake. The engine should be cold.
- Start the engine and let it idle in park for 3 minutes. During this time, you may notice the idle is high or erratic. This is normal. The RPMs should start to decrease as the PCM begins learning the new settings.
- After 3 minutes, turn the ignition off and wait 60 seconds.
- Restart the engine and let it idle for another 3 minutes in park. After this second 3-minute period, the idle should be noticeably improved and more stable.
- Turn off the ignition. The initial throttle relearn is complete.
In some cases, a check engine light may come on during the relearn process indicating there are idle speed-related diagnostic trouble codes stored. If this happens, clear the codes using a scan tool so the PCM can continue the learning process.
Completing the Relearn with a Drive Cycle
If the engine idle still seems incorrect after the initial relearn, an additional drive cycle may be needed for the PCM to fully learn the new throttle settings. To do this:
- Drive the vehicle at speeds over 44 mph (70 km/h).
- Include several periods of deceleration and extended idling.
- After completing the drive cycle, the idle quality should be back to normal.
- If the idle still seems off, turn the ignition off for 60 seconds and repeat the initial 3-minute idle relearn again.
Importance of the Throttle Relearn
Skipping the throttle relearn procedure after a throttle body replacement can lead to ongoing drivability issues like:
- Rough or unstable idle
- Stalling
- Hesitation or stumbling on acceleration
- Poor fuel economy
Taking the time to do the relearn ensures your Changan will have optimal performance and efficiency with the new throttle body installed. It’s a critical step in completing the repair.
Troubleshooting Throttle Relearn Issues
If you’ve completed the relearn procedure as outlined above but your Changan still has idle or drivability problems, there are a few things to double-check:
- Make sure the throttle body is installed correctly with no air leaks. A vacuum leak can cause idle issues.
- Check that all electrical connections to the throttle body are secure and corrosion-free. Poor electrical connections can prevent proper relearn.
- Confirm the throttle body itself is not defective. While rare, a faulty replacement part may be the culprit.
- Inspect the idle air control valve for carbon buildup or sticking. The IACV works in conjunction with the throttle body to control idle.
If you’ve ruled out these potential issues and the problem persists, there may be a deeper problem with the PCM or wiring harness. At this point, it’s best to have your vehicle diagnosed by a professional Changan technician who can use a scan tool to check for trouble codes and test system components.
Conclusion
The throttle relearn is a necessary procedure when replacing the electronic throttle body on Changan CS35, CS55, CS75, CS85, CS95, Eado, and Raeton models. Performing the relearn allows the PCM to adapt to the new throttle body, restoring optimal idle quality and engine performance.
By following the straightforward steps outlined in this guide, Changan owners can complete the throttle relearn at home without any special tools in under 30 minutes. Drive cycle adaptation may also be required for full relearn on some vehicles.
If idle problems persist after the relearn, ruling out installation issues and part defects is recommended. Stubborn relearn problems are best diagnosed by a qualified Changan repair shop.
Taking the time to properly complete the throttle relearn after a throttle body replacement will ensure your Changan runs right and delivers the drivability and efficiency you expect. It’s a critical step in finishing the job right.
Key Takeaways
- The throttle relearn procedure is necessary when replacing the electronic throttle body on many Changan models to restore proper idle quality.
- The relearn process allows the PCM to adapt to the new throttle body and relearn the correct throttle blade angle settings.
- Changan models like the CS35, CS55, CS75, CS85, CS95, Eado, and Raeton require a throttle relearn after throttle body replacement.
- The relearn is performed by idling the engine in park for two 3-minute cycles, separated by a 60-second ignition off period. No scan tool is needed.
- An additional drive cycle at highway speeds with extended idling may be needed to complete the relearn on some vehicles.
- If idle problems persist after the relearn, the throttle body installation and components should be inspected for issues before diagnosing further.
FAQ
What happens if I don’t perform the throttle relearn on my Changan?
If you skip the throttle relearn after replacing the throttle body, your Changan may experience ongoing idle quality and drivability issues like rough idle, stalling, stumbling on acceleration, and poor fuel economy. The relearn is necessary for the PCM to correctly adapt to the new throttle body.
Can I perform the Changan throttle relearn at home?
Yes, the throttle relearn procedure on Changan models like the CS35, CS55, CS75, CS85, CS95, Eado, and Raeton can be performed at home with no special tools. All that is needed is a safe place to park and the vehicle’s ignition key. The full relearn takes less than 30 minutes.
Why is my Changan idling rough after a throttle body replacement?
A rough or erratic idle after throttle body replacement on your Changan is normal if the throttle relearn procedure has not been performed yet. The rough idle is caused by the PCM still operating with the learned settings from the old throttle body. Completing the relearn will allow the PCM to adapt to the new part, restoring normal idle quality.
What Changan models need a throttle relearn after throttle body replacement?
According to the Changan service manual, the following models require a throttle relearn procedure after installing a new electronic throttle body:
Changan CS35
- Changan CS55
- Changan CS75
- Changan CS85
- Changan CS95
- Changan Eado
- Changan Raeton
Other Changan models may also require a throttle relearn. Consult your owner’s manual or Changan dealer to confirm the procedure for your specific vehicle.
How long does the Changan throttle relearn take?
The basic Changan throttle relearn procedure takes less than 30 minutes and can be performed at home. It involves idling the engine for two 3-minute periods in park, separated by a 60-second ignition off interval.
In some cases, an additional drive cycle at speeds above 44 mph (70 km/h) with periods of deceleration and extended idling may be needed to complete the relearn. After the drive cycle, if the idle quality still seems off, the initial 3-minute idle relearn can be repeated again.
Do I need a scan tool to perform the Changan throttle relearn?
No, a scan tool is not required to perform the throttle relearn on Changan models like the CS35, CS55, CS75, CS85, CS95, Eado, and Raeton equipped with an electronic throttle body. The relearn can be completed with just the vehicle’s ignition key by idling the engine in park for specific intervals.
However, if the check engine light illuminates during the relearn indicating stored idle speed-related trouble codes, a scan tool can be used to clear those codes so the PCM can continue the learning process. If idle problems persist after the relearn, a scan tool may be helpful for further diagnosis.
What causes a Changan to need a throttle body replacement?
A Changan may require a throttle body replacement for several reasons, including:
- Carbon buildup on the throttle blade and bore causing a sticky throttle
- Worn or damaged throttle position sensor providing incorrect readings
- Broken throttle return spring preventing smooth operation
- Stripped gears in the throttle body motor
- Cracked throttle body housing causing vacuum leaks
In some cases, cleaning the existing throttle body may resolve idle and drivability issues. However, if the throttle body is physically damaged or the sensors and motors have failed, replacement is necessary. A throttle relearn is then required to complete the repair.
The Importance of Proper Throttle Body Function
The electronic throttle body is a critical component in your Changan’s air intake system. It controls the amount of air flowing into the engine, which in turn affects engine speed, power output, and fuel efficiency.
When you press the accelerator pedal, the throttle position sensor on the throttle body sends a signal to the PCM indicating how much to open the throttle blade. The PCM then adjusts fuel delivery and other engine parameters accordingly to provide the requested power.
Over time, carbon deposits can accumulate on the throttle blade and bore, causing the throttle to stick or respond sluggishly. The throttle position sensor can also wear out, providing inaccurate readings to the PCM. A faulty throttle body can cause symptoms like:
- Poor idle quality
- Rough running
- Hesitation on acceleration
- Stalling
- Reduced fuel economy
- Illuminated check engine light
In some cases, cleaning the throttle body may resolve these issues. However, if the throttle is sticking, damaged, or has failed sensors, replacement is necessary to restore proper operation.
When a new throttle body is installed, the PCM needs to relearn the throttle blade angle settings. The relearn procedure allows the PCM to establish a new baseline for the throttle position sensor and adjust idle speed and fuel trims accordingly.
Skipping the throttle relearn can result in ongoing drivability issues, as the PCM will still be operating with the learned settings from the old throttle body. Taking the time to properly complete the relearn ensures your Changan will have optimal throttle response, idle quality, and efficiency.
Changan Throttle Body Preventive Maintenance
To help extend the life of your Changan’s electronic throttle body and prevent the need for premature replacement, some preventive maintenance is recommended:
Throttle Body Cleaning
Over time, carbon deposits can build up on the throttle blade and bore, causing the throttle to stick or respond poorly. Periodic cleaning of the throttle body can help remove these deposits and restore smooth operation.
Changan recommends inspecting and cleaning the throttle body every 60,000 miles or as needed if throttle response issues are noted. A throttle body cleaning involves:
- Removing the air intake duct to access the throttle body.
- Spraying throttle body cleaner on the throttle blade and into the bore.
- Working the throttle open and closed to help dissolve and remove carbon buildup.
- Wiping away any loosened deposits with a clean rag.
- Reinstalling the air intake duct.
On Changan models, a throttle relearn procedure should be performed after cleaning the throttle body to restore proper idle quality.
Changing the Air Filter
A dirty or clogged engine air filter can restrict airflow into the throttle body, leading to poor throttle response, reduced power, and decreased fuel economy. Changan recommends replacing the engine air filter every 30,000 miles or more frequently if driving in dusty conditions.
When changing the air filter, it’s a good opportunity to inspect the condition of the throttle body. If heavy carbon buildup is noted, cleaning the throttle body at the same time is advised.
Using High-Quality Fuel
Using low-quality or contaminated fuel can cause increased carbon buildup on the throttle body and other fuel system components. Changan recommends using high-quality gasoline from a reputable supplier to help minimize deposits and keep the throttle body and fuel injectors clean.
If you suspect you’ve received bad fuel, having the throttle body and fuel injectors cleaned as soon as possible can help prevent further buildup and potential damage.
By following these preventive maintenance recommendations, you can help extend the life of your Changan’s throttle body and avoid the need for premature replacement. However, if you do notice symptoms of a sticking or faulty throttle body, have it inspected and replaced as needed to restore proper operation.
Changan Throttle Body Replacement and Relearn Tips
If you need to replace the throttle body on your Changan CS35, CS55, CS75, CS85, CS95, Eado, or Raeton, following some key tips can help ensure a successful repair and relearn:
Use OEM or High-Quality Aftermarket Parts
When replacing the throttle body, it’s important to use either a genuine Changan OEM part or a high-quality aftermarket replacement. Using a cheap, low-quality throttle body can lead to fitment and performance issues, as well as a shorter service life.
Genuine Changan throttle bodies are designed specifically for your vehicle and are built to the same quality standards as the original. They may cost more upfront but can save money in the long run by lasting longer and providing better performance.
If using an aftermarket throttle body, choose a reputable brand with good reviews. Look for a part that is built to OEM specifications and comes with a warranty.
Clean the Throttle Body Mounting Surface
Before installing the new throttle body, take the time to clean the mounting surface on the intake manifold. Over time, the old gasket can leave behind residue and debris that prevents the new throttle body from sealing properly.
Use a plastic scraper or gasket removal tool to remove any old gasket material. Then, clean the surface with brake cleaner and a lint-free rag until it is completely clean and dry. This will help ensure the new throttle body seals correctly and prevents vacuum leaks that can cause idle issues.
Replace the Throttle Body Gasket
Always install a new throttle body gasket when replacing the throttle body. The gasket helps seal the connection between the throttle body and intake manifold and prevents air leaks.
Most new throttle bodies will come with a new gasket. If yours does not, make sure to purchase the correct gasket for your Changan model. Using the old gasket or the wrong gasket can lead to sealing issues and idle problems.
Perform the Throttle Relearn Correctly
After installing the new throttle body, the throttle relearn procedure must be performed to allow the PCM to adapt to the new part. On Changan models, the relearn involves idling the engine in park for two 3-minute periods, separated by a 60-second ignition off interval. It’s important to follow the relearn steps exactly as outlined to ensure the PCM learns the new settings correctly.