Injectors or fuel pump or vacuum leak?

Hi,

By chance, have you scanned the computer to see if there are diagnostic trouble codes stored? I ask because this could be several things. It could be fuel-related (too much or too little), it could be a crankshaft position sensor failing, even a partially plugged catalytic converter can be the issue. I question if it's a vacuum leak, but anything is possible.

Take a look through this link first:

https://www.2carpros.com/articles/engine-backfires-while-running

Also, I will need to know the engine size. Let me know if that link helps in any way and if you have a scan tool to work with.

Let me know as much as you can so I can better help.

Take care,

Joe

Hi,

If there was a lean or rich fuel mixture, it should have set a code. The same if it was a plugged converter. Does your scan tool have live data? If it does, I need you to check two things.

First, with the engine cold, check the engine coolant temperature sensor reading. Start the engine, allow it to warm up in an open-loop condition, and see what the short-term fuel trims are.

If you don't have a scanner, inspect the wiring at the crankshaft position sensor. The Crankshaft Position (CKP) sensor is located near the outer edge of the flywheel (starter ring gear). See pic 1 for location. It's right near the exhaust manifold and the wiring takes a lot of heat.

Let me know what you find.

Joe

See pic below.