backfiring?

1994 CADILLAC DEVILLE

150,000 MILES • 4.9L • V8 • 2WD • AUTOMATIC

CADDYBOI SHAUN

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So far, I have replaced the MAP sensor, Oil pressure sensor and it's had a tune up consisting of spark plugs, spark plug wire, distributer cap and rotor yet it is still backfiring to the point where I'm not able to drive. I have been told it can be the crankshaft sensor or alternator since. Also, this problem started when my voltage started jumping all over the place. Hopefully somebody has an answer because I'm stumped.

Mar 1, 2024 at 6:26 AM

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JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

A backfire can be the result of several different things. For example, a rich or lean fuel mixture can cause it, a burnt valve, ignition or engine timing, and so on.

Take a look through this link first:

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

If that doesn't help, I need you to scan the computer to see if there are codes stored. This vehicle has an OBD1 system, so you don't need a scan tool. All you will need is a short jumper wire or even a paper clip. Follow the directions in this link and let me know the results:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Let me know.

joe

Mar 1, 2024 at 8:37 PM