I have a 1961 ford Galaxie with a big block 390.. it starts up fine. After driving for awhile she will backfire every so often, but at low speed/rpm’s she loses power at acceleration, backfires loudly and stalls. Have to shift back into park to keep car idling..At normal driving or freeway speeds car seems to run fine.
Noticed the other night we went on cruise with bunch of other cars looking at Christmas lights through neighborhoods.. cars started to run rough at the slow pace we were driving... but once I was able to get some speed she ran normal
My car has an automatic transmission.
Backfiring is often caused by a too lean or too rich air-to-fuel ratio although a few other causes are discussed below. A backfire in the intake manifold is caused by a ratio that is too lean (not enough fuel). A backfire out the exhaust system is caused by a ratio that is too rich (too much fuel). If backfiring is occurring, it is recommended that you request a diagnostic to identify and resolve the root of the problem. Some other possible causes of backfiring are moisture or resistance in the car’s ignition system that allows a crossover generation of current to the wrong cylinder; a lean mixture caused by either an engine vacuum leak or low fuel-pump pressure; faulty ignition components or spark plugs may also cause backfires if the ignition timing drifts off or the plugs fire intermittently; and an exhaust leak such as broken welds or other small holes can take in cool air during deceleration and cause a popping or backfiring in the exhaust system. If you request a backfiring diagnostic the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
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