Engine backfire on decelleration Timing Checked

have you checked the timing chain for wear because if the chain gear has chipped it can cause that to happen, some of those chains are made of plastic Teflon and they can brake off so I would look to see if that might be the problem, or recheck the points and the timing.

Sounds like a fuel delivery problem. Have you checked fuel pressure with a gauge?

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This could be anything from bad ignition to timing to bad fuel supply (lean) to bad valves in engine. Run compression test to eliminate worst case, check both ignition and cam timing, vacuum leaks, ignition module.

Mrs Tercia,have you checked whether you might have either blocked exhaust system or Broken and blocked Catalytic converter? What I mentioned are the main cause of loosing power,backfiring and make the car not drive able and possible blow either the engine or catch fire.

check for leaking injectors and vacuum leaks as there is fuel getting into the exhaust system and igniting. check ignition timing as it may be retarded too far.

• Backfiring in internal combustion engines occur outside of the combustion chamber, and are typically the result of an improper air to fuel ratio. This can be caused by a vacuum leak, Idle air control valve, throttle position sensor, oxygen sensor, or just about any part of your emissions contorl system.



• Backfires may also occur before the combustion chamber. One possible cause of this is igniton timing. If the timing is too advanced, the spark plug fires before the intake valves close, causing the combustion to propagate into the intake manifold, further igniting the air-fuel mixture there; the resulting explosion then travels out of the carburetor or intake and air filter. Alternatively, the engine timing may be retarded, in which case the combustion is not completed by the time the exhaust valves open, allowing the combustion to propagate into the exhaust system.



• Improper wiring of the ignition can also lead to timing issues and backfires, or faulty coil or igniton modules.



• Low fuel pressure, clogged fuel filters, and weak fuel pumps could cause a severe lean air-to-fuel ratio with fuel injection systems.



• Missing or damaged catalytic converters can result in backfires out the tailpipe, but very uncommon, and usually only applies to engines set up for race applications.

Backfiring on throttle-closed decelleration is usually caused by cold air being sucked into a hot exhaust systen. Check for poor seal where the downpipe meets the cylinder head, and leakage at any joints beneath the engine if it has a balance pipe. Hope that helps.

Timing chain may have slipped a link.

egr system not functioning properly, vacuum leak, intake air vacuum leak.

put a vacuum guage on the intake I hope its an automatic one foot on the brake and one on the gas in drive slowly accelarate if the vacuum falls to or near O as you accelerate you have a restricted exhaust,
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