Location: If your Bonneville has one, the EGR valve is typically located on the intake manifold. It's a relatively small valve, often with a vacuum line connected to it. You'll probably need to consult a repair manual specific to your Bonneville's engine (3.1L or 3.8L) for the exact location. A visual inspection, searching online for images of "1992 Pontiac Bonneville 3.8L EGR valve" (or 3.1L, as appropriate) might help.
Can a bad EGR valve prevent starting or proper running?
A faulty EGR valve can cause a variety of problems, but it's less likely to completely prevent your car from starting. It's more likely to cause issues *while* the car is running. Problems associated with a bad EGR valve include:
* Rough idling: The engine may idle roughly or stall.
* Poor performance: Loss of power, hesitation during acceleration.
* Check engine light: This will almost certainly illuminate, with a code related to the EGR system.
* Increased emissions: More pollutants are released into the atmosphere.
* Hard starting (less common): While not a primary cause of starting failure, a severely clogged EGR valve *could* contribute to starting difficulty in some situations by affecting the air/fuel mixture.
If your Bonneville won't start, there are far more likely culprits, such as a dead battery, faulty starter, fuel pump problems, or ignition issues. A bad EGR valve is more likely to manifest as running problems *after* the car starts.
Recommendation: If you're having starting or running problems, it's best to get a diagnostic check done. An OBD-II scanner can read the codes stored in your car's computer, which will point you towards the likely source of the problem. Don't jump to conclusions about the EGR valve until you've done some basic troubleshooting.
