1996 toyota camry backfiring

1996 TOYOTA CAMRY
150,000 MILES • 4 CYL • FWD • MANUAL
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JLLOYD
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I just recently put the engine back together in my camry. I had to fix the tranmission, and I am a mechanic so I know it was put back properly. the car started to backfire, so I went to the timing belt. the belt is on perfectly, so I dont know what else it can be. I am thinking it is a sensor, but I am unsure. Please help. I have already put $1000.00 in this car, and I dont want to trash it.. the engine shakes and acts like its going to die when it idles, and when i accelerate it pops (backfires) real loud. It is coming from the engine.
Apr 24, 2011 at 5:14 PM
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DOCFIXIT
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do a push test see if internal good
Apr 24, 2011 at 5:40 PM
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JLLOYD
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What is a push test?
Apr 25, 2011 at 2:16 AM
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DOCFIXIT
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Thought you are a mechanic compression test
Apr 25, 2011 at 5:40 PM
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JLLOYD
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Ok did a compression test today and all were within spec. The check eng light is flashing when missfireing but will not store a code. Data stream shows like a 60% load at idle. Im thinking its a faulty pick up coil in the distributer its a 2.2 4sfe motor. pick up coil ohms at spec but the car runs the same wether its unpluged or pluged in but does set a code when unpluged.
Apr 27, 2011 at 1:49 AM
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DOCFIXIT
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Is valve clearence correct? check crank sensor ohms cold 945-1600 was pick up 135-220 ohms cold? can you read missfire history?
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Apr 27, 2011 at 4:01 PM
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JLLOYD
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I did not mess with the valves when i had the motor out. The car ran fine whe i pulled the motor i did power wash when i had it out. the pickup coil ohms @164 at room temp. My scanner did pick up a code for random multiple missfire but will not show freeze frame data for that code
Apr 27, 2011 at 11:34 PM
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DOCFIXIT
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May have damaged crank sensor during power wash check it out. Code P0300 comes up that is by far MOST difficult to solve.Also is fuel pressure good?
Apr 28, 2011 at 6:18 PM
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JLLOYD
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Fuel pressure is ok i replaced the cps sensor because it didnt ohm out correct when at operating temp
Apr 28, 2011 at 11:18 PM
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FOXKW
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You probably solved this by now, but check the O2 Sensors and the Manifold Catalytic converter. I had a similar problem following an Automatic Transmission swap - the car would start, run, and drive but any sort of load would cause it to stumble badly. This cause the random undiagnoseable (really uncorrectable) misfire codes. Drove me nuts.

I got an inspection camera to check if the intake valves were loaded up with gunk for some reason ( it had 325000+ miles at the time) but they were clean. On a lark I pulled the upstream 02 sensor to look at the exhaust valves, and found nothing there either. So I looked in the other direction at the catalytic converter, and saw a lone white spot about 1.5 -2 inches (35-50mm) in diameter, and decided to pull it thinking it was "starting to go". Turns out the white spot was the ONLY part of the cat flowing. The ends looked all nice but the core of the thing was melted, and therefore clogged.

(I now have a Toyota specific "test pipe")

Replacing the catalytic converter after verifying it was clogged solved my problem. (Note that had I NOT previously replaced the O2 sensor, I would have done so with the new cat because a bad O2 sensor is the fastest way I know to kill a catalytic converter.)

BTW I still drive the Camry and it has 355,000 Miles on it.
Mar 30, 2014 at 9:14 AM