EGR solenoid
EGR solenoid refers to the electrically controlled vacuum solenoid used by the Pontiac Fiero EGR system.
The EGR solenoid controls vacuum to the EGR valve. The ECM controls the solenoid to determine when EGR operation is allowed.
Overview
The EGR solenoid is part of the exhaust gas recirculation system.
The ECM does not open the EGR valve directly. Instead, it controls the EGR solenoid, which controls vacuum to the EGR valve. When the correct operating conditions are present, vacuum is allowed to reach the EGR valve so that exhaust gas can be recirculated into the intake.
A faulty EGR solenoid, wiring problem, vacuum-line problem, connector problem, or internal solenoid failure can cause EGR problems and may set Code 32.
Location
Image wanted: Photo or diagram showing the EGR solenoid location on the Fiero. Ideally include the 2.8L V6 solenoid, vacuum-line routing, and connector location.
The EGR solenoid location depends on engine and year.
On the 2.8L V6, the EGR solenoid is mounted in the engine compartment near the intake area and is connected to the EGR valve by vacuum lines.
On the 2.5L four-cylinder, the EGR vacuum-control layout may vary by year and engine configuration.
The EGR solenoid should not be confused with the EGR valve. The solenoid controls vacuum; the valve controls exhaust-gas flow.
Function
The EGR solenoid controls whether vacuum is applied to the EGR valve.
The ECM uses operating conditions such as engine temperature, load, rpm, and throttle position to determine when EGR should operate.
When EGR operation is desired, the ECM commands the solenoid so that vacuum can reach the EGR valve.
Related trouble codes
EGR-solenoid-related diagnostic trouble codes include:
- Code 32 - EGR system
Code 32
Code 32 indicates that the ECM has detected a problem with EGR vacuum control or EGR system operation.
Possible EGR-solenoid-related causes include:
- Defective EGR solenoid
- EGR solenoid wiring problem
- Poor connector contact
- Vacuum leak at the solenoid
- Broken or disconnected vacuum lines
- Internal solenoid vacuum failure
- ECM control problem
Symptoms
Possible symptoms of an EGR solenoid or EGR vacuum-control problem include:
- Check engine light
- Code 32
- Failed emissions test
- Spark knock or pinging
- Poor drivability under some conditions
- Rough running under some conditions
- Little or no obvious drivability problem
Vacuum lines
The EGR solenoid depends on correct vacuum-line routing and good hose condition.
Possible vacuum-line problems include:
- Cracked hoses
- Disconnected hoses
- Brittle plastic vacuum lines
- Incorrect routing
- Leaking fittings
- Collapsed hoses
Vacuum-line problems should be checked before replacing the solenoid.
Electrical connection
The EGR solenoid is controlled electrically by the ECM.
Possible electrical problems include:
- Poor connector contact
- Corroded terminals
- Broken wiring
- Shorted wiring
- Open circuit
- ECM control problem
Diagnosis
Basic diagnostic checks include:
- Check for stored diagnostic trouble codes.
- Inspect the EGR solenoid connector.
- Inspect the EGR solenoid wiring.
- Inspect all EGR vacuum lines.
- Check for cracked, disconnected, brittle, or incorrectly routed vacuum hoses.
- Check whether vacuum reaches the solenoid.
- Check whether vacuum is passed to the EGR valve when commanded.
- Check the EGR valve operation.
- Check the EGR tube for leaks if idle or vacuum-leak symptoms are present.
- Check ECM control and wiring if the solenoid and vacuum system appear correct.
Relationship to the EGR valve
The EGR solenoid and EGR valve work together, but they are separate parts.
The solenoid controls vacuum.
The valve controls exhaust-gas flow.
A Code 32 can be caused by either part, but vacuum lines, wiring, connectors, and the EGR tube should also be checked.
Notes
Code 32 should not automatically be treated as a failed EGR solenoid.
Vacuum-line leaks, wiring faults, poor connectors, EGR valve problems, EGR tube leaks, and ECM control problems can all affect EGR operation.
Because the EGR solenoid uses both electrical control and vacuum control, both sides of the system should be diagnosed.