Answers
Aug 20, 2024 - 10:37 PM
Hi there,
Based on the trouble codes you provided and the symptoms you've described, it seems the issues are related to the evaporative emissions control system (EVAP). Here are the issues explained and how they relate to the problem:
1. Trouble code P0449. This points to an issue EVAP vent valve (emission control system vent valve/solenoid circuit malfunction). The valve might not be opening and closing properly, which could prevent the system from purging vapors as it should.
2. Trouble code 0452. It points to an evaporative emission control system pressure sensor low input. The standard pressure is lower than expected. A possible faulty sensor, wiring issues, or a leak in the EVAP system.
3. Trouble code P0463. It shows a fuel level sensor circuit with high input. It indicates an issue with the fuel level sensor. A high voltage, (more than the started reading) shows a faulty fuel level sensor.
4. A 100% purge. The system is trying to purge vapors from the fuel tank into the engine to be burned. The possible causes are a blocked or restricted purge valve, a faulty purge valve solenoid, and leaky or pictured hoses. Check and clean the purge valve & hoses. Replace the purge valve if faulty.
5. Fuel tank pressure issue. The pressure is below standard. Possible leaky fuel cap, faulty vent valve, and blocked or restricted vent hose.
I hope all those details help and give you an idea of the causes and possible solutions. Please do not hesitate to consult your trusted auto repair shop or mechanic for extensive troubleshooting and repair.
Aug 21, 2024 - 01:35 PM
While driving - with scanner connected, what are typical purge values ? What should fuel VP range be ? I never can get those answers.
Thx
Thx
Aug 21, 2024 - 10:47 PM
Hi there,
When using a scanner to monitor the purge valve and vapor pressure while driving, the typical values might vary depending on the vehicle, driving conditions, and engine load. Here is a general guide to what you should expect:
1. Purge valve (Purge duty cycle or percentage).
- idle or low load. The purge valve is usually slightly open during idle or low engine load. the typical purge duty cycle at idle time might be between 5% to 20%.
- moderate load. As the engine load increases, the purge valve opens more to allow more fuel vapors into the intake manifold. You might see values ranging from 20% to 50%.
- high load (highway driving, acceleration). The purge valve can open even more up to 50% to 100%. Full throttle or heavy acceleration might result in a near 100% purge cycle if the EVAP system demands it.
- deceleration or engine off. The purge valve is typically closed which results in a 0% duty cycle.
2. VP range (fuel VP or Fuel tank pressure).
- normal operating range. the fuel vapor pressure sensor measures the pressure or vacuum in the fuel tank or EVAP system. The typical pressure range can vary, but you generally see values between -1.5 kPA to 1.5 kPA (approx values close to -2.0 kPA or more.)
- under load. When the purge valve opens, and the EVAP system is operating, you should see a slight vacuum increase in the fuel tank indicating negative pressure values closer to 2.0 kPA or more.
- positive pressure. After fueling or with a hot fuel tank, you might see a slight positive pressure in the system, up to 2.0 kPA.
- fuel tank venting. During venting operations, the pressure should stabilize and stay within the above ranges. If the pressure goes too high or low, it could indicate a malfunction, such as a blocked vent or faulty sensor.
Take note:
Vehicles may have different "normal" ranges, so it is essential to refer to a vehicle-specific repair service manual. Please check with your trusted auto repair shop or mechanic for further details about this issue. I hope the details help!
Aug 24, 2024 - 08:06 AM
Thanks ! Still working on. Installed a new tank pressure sensor. Drove it some. Not setting those codes now, but scanner still says an EVAP problem. Minus pressure in tank while driving is -0.3 ( inH20 ). Apparently that is low. Maybe I did smoke test wrong. Where should smoke be put into system to check for leaks ? I was using the vent hose at the purge valve. It expanded the tank a bunch before I stopped it. Didn't see a leak that way.
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