More than likely this is either a vacuum leak or the purge valve is sticking open and causing the engine to run rich. Basically, what happens is when the engine is cold the PCM ignores the o2 sensor data until it gets hot. So that means when the PCM does not see if it is rich or lean until it gets hot. Once the engine is hot, it sees that the exhaust is not correct and it starts making adjustments to make it run smooth.
Here are some guides that will get us started but let's check for a vacuum leak.
https://www.2carpros.com/articles/vibration-noise
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
If you do not find a vacuum leak, then we need to use a scan tool to not only check for codes but also monitor the o2 sensor data when it is running poorly.
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing
Even though the PCM ignores the o2 data, you are still able to see what it is. If it is rich, then we need to remove and inspect the purge valve.
Please see the chart below on the fuel trim data that will tell you if it is rich or lean.
Let us know what questions you have, and we can go from there.
Thanks
Jan 2, 2022 at 9:48 AM
