backfires in engine when cold, don't run long when warm
 

Hello everybody, I new here I have a taco and now i'm the toy mechanic (good luck for them) My buddie's 16yr Daughter first car is a 4 cylinder toyota Camry for the first month it ran great but now it started back fireing when it is cold and loss of power and it will only stay running for a short time, changed the spark plugs and fuel filter seemed better for a couple of hours still backfireing in engine when cold, and continued to die when running for a min or so. I'm no mechanic so I came where the expert go. thanks

Year of car?

1989 sorry

backfiring is backfiring. timing is not right. for the year, either timing belt slipped, or one of the sensors is bad, or engine computer. read codes off computer.

would the engine light come on , the bulbs been checked and good.

try to check the ignition timing and also the error code.

ok thanks

Does the engine back fire through the air intake or the exhaust pipe?

If the engine can run long enough to warm up, does it run better?

intake and yes runs better when warm

Could be running too lean.

What is the fuel pressure?

No clogged fuel injectors?

When starting an engine, timing that is too advanced will fire the spark plug before the intake valve is closed. The flame front will travel back in to the intake manifold, igniting all of that air and fuel as well. The resulting explosion then travels out of the carburetor and air cleaner. A common air filter will allow the gases to escape, but will block the flame front. On many small marine engines, no air filter is used, but a screen is placed over the intake of the carburetor as a flame arrestor to prevent these flames from escaping the intake, and potentially igniting fuel, or fuel vapors in the enclosed sump or bilge of the boat and causing a fire or explosion. Improperly adjusted carburetors that create a lean condition during acceleration can cause the air fuel mixture to burn so slowly, that combustion is still taking place during the exhaust stroke, and even when the intake valve opens. The flame front can then travel up the intake and cause a backfire. In this situation it is conceivable that there is a backfire occurring in the intake manifold and exhaust manifold simultaneously.
[edit] Causes

Exhaust system backfires occur in engines that have an emission system malfunction, like an air injection system diverter valve problem, an exhaust leak, or when the catalytic converter has been removed. In some high-performance vehicles, when a driver shifts up and lets off the accelerator, the engine has a moment of running rich. This causes an incomplete burn which causes the fumes to explode in the exhaust system along with an audible pop or bang sound. This is a result of working equipment, and is unlikely to cause damage.
A fuel-injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air-flow sensor is defective.
Common causes of backfires are:

• Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires
• Improper wiring in the ignition can also lead to timing issues and backfires
• Low fuel pressure, clogged fuel filters, and weak fuel pumps could cause a severe lean air-to-fuel ratio during fuel injection
• Missing or damaged catalytic converter can result in backfires out the tailpipe

alterator output was 14.15V

Alt output is OK.

One other place to check is the coil, the body can crack and result in poor spark. Check the body for cracks.

Run the engine in the dark, check for signs of arcing or a blue glow at the ign wires and coil.