'92 4.0 L. Many times when I let the gas pedal off for shifting, i hear a "pop" on the exhaust pipe. It happens even at normal engine working temperature (i.e. after warming up). I think it may be unburnt fuel that eventually burns in the hot exhaust. Is that popping normal in these cars or I am having an engine issue? (like injectors leaking or something?) Noticed OBD code 17 recently. Wondering if the ECU is making the mix too rich even after the engine is warm. I don't notice anything particularly wrong with performance, but I have no base line as to how a good engine should perform, for it was a well-used vehicle when purchased. Any ideas?
Exhaust pop noise
- Thread starter rct2000
- Start date
This sort of noise can often be attributed to unburnt fuel igniting in the exhaust system, which is a scenario that can occur if the air-fuel mixture is too rich.
A few things to consider:
1. OBD Code 17: This code indicates a problem with the speed sensor, which generally affects shift points and can affect engine performance. While it may not directly cause the popping, it could indirectly contribute to inconsistent fuel delivery.
2. Fuel Injectors: If they’re leaking or not functioning properly, this could lead to a richer mixture. Since you’re not experiencing obvious performance issues, it may be beneficial to have them cleaned or inspected.
3. Exhaust System: Check for any leaks or cracks in the exhaust system downstream of the engine. Exhaust leaks can sometimes cause popping sounds as well.
4. Ignition Timing: If the timing is off, it can lead to incomplete combustion, resulting in unburnt fuel entering the exhaust. If you haven't checked or adjusted the timing in a while, it's worth looking into.
5. Regular Maintenance: Ensure that you're maintaining regular oil and filter changes. A clogged air filter can also affect the air-fuel mixture.
Given that you don’t notice a drop in performance, it might be nothing serious, but addressing the OBD code and possibly having the fuel system and exhaust system checked would be good steps to take. If you’re comfortable doing so, a data logger or live data from the OBDII system during idle, acceleration, and cruising can help identify if the mixture is leaning or rich at different points.