Iron Weasel
Well-Known Member
- Joined
- March 22, 2010
- Messages
- 608
- Reaction score
- 3
- City, State
- Belen, New Mexico
- Year, Model & Trim Level
- 1994 XLT 4x4
Coasting is low vacuum, so the voltage is low.
When you're wide open, that's high vacuum so the voltage is high.
When there's a low amount of vacuum on the EVR solenoid, it sends a low amount of voltage to the PCM, and the PCM in turns tells the EVR solenoid to close and restrict vacuum going to the EGR valve causing it to close. During high vacuum, like when you're at full throttle, the opposite is true. High vacuum at the EVR solenoid causes the voltage to raise and the PCM tells it to open and increases the vacuum on the EGR valve causing it to open.
I'm not sure what amount of vacuum there should be at idle, but the purpose of using a vacuum gauge is to make sure that the EGR valve operates smoothly on its own.
Your best bet is to start poking around with the vacuum gauge. Here's DL99, the only step I didn't post yesterday:
Vacuum gauge connected.
Key on, engine running.
Look for an increase in EGR vacuum while performing the following:
With the engine at idle, wiggle the EGR Vacuum Regulator (EVR) solenoid harness between the EVR solenoid and dash panel and between dash panel and Powertrain Control Module (PCM) .
Does the EGR vacuum increase?
Yes -- Isolate and service short in EVR circuit. Remove vacuum gauge. Reconnect all components. Clear continuous memory. See: Reading and Clearing Diagnostic Trouble Codes\Clearing Diagnostic Trouble Codes
Rerun quick test. See: Reading and Clearing Diagnostic Trouble Codes\Reading Diagnostic Trouble Codes\Quick Test Appendix (Detailed Testing Instructions)
No -- Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, refer to Normal Scan Data Values .
When you're wide open, that's high vacuum so the voltage is high.
When there's a low amount of vacuum on the EVR solenoid, it sends a low amount of voltage to the PCM, and the PCM in turns tells the EVR solenoid to close and restrict vacuum going to the EGR valve causing it to close. During high vacuum, like when you're at full throttle, the opposite is true. High vacuum at the EVR solenoid causes the voltage to raise and the PCM tells it to open and increases the vacuum on the EGR valve causing it to open.
I'm not sure what amount of vacuum there should be at idle, but the purpose of using a vacuum gauge is to make sure that the EGR valve operates smoothly on its own.
Your best bet is to start poking around with the vacuum gauge. Here's DL99, the only step I didn't post yesterday:
Vacuum gauge connected.
Key on, engine running.
Look for an increase in EGR vacuum while performing the following:
With the engine at idle, wiggle the EGR Vacuum Regulator (EVR) solenoid harness between the EVR solenoid and dash panel and between dash panel and Powertrain Control Module (PCM) .
Does the EGR vacuum increase?
Yes -- Isolate and service short in EVR circuit. Remove vacuum gauge. Reconnect all components. Clear continuous memory. See: Reading and Clearing Diagnostic Trouble Codes\Clearing Diagnostic Trouble Codes
Rerun quick test. See: Reading and Clearing Diagnostic Trouble Codes\Reading Diagnostic Trouble Codes\Quick Test Appendix (Detailed Testing Instructions)
No -- Unable to duplicate and/or identify fault at this time. For further diagnosis using the EEC-IV monitor box or Scan Tool, refer to Normal Scan Data Values .