Need help! Plzzz

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John/castelli

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I have a 94 ram 1500 with the 360 an I need help soon!
The other day it started pooping under a load! Its losses power as soon as it starts popping!
I can't find a vacuum leak an there are no bad plugs or wires! It seems to b coming from my intake box! I don't have any idea what it is or y it's doing it!
 

dapepper9

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Backfire under load is probably fuel or spark related. Ohm check the coil for 12-15k ohms batten the tower and either pin and check fuel pressure
 

dudeman2009

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I had a similar issue, I had poor spark on all cylinders. That was the cause of the popping, the cause of the poor spark in my case was a distributor cap that had cracked and wasn't making good contact with the rotor. You could have a similar issue, or it could be the coil, or the primary wire going from the coil.

As Dapepper suggested, ohm check your coil.

Between the two pins on the bottom of the coil, you should get right around 1 ohm, between the tower and a pin, it should be right around 12-15K ohm.

I don't have as much experience as dapepper on whether or not low fuel pressure could cause popping, I mainly worked on Diesels, but even on them, poor ignition, for whatever reason, can cause similar problems in a diesel.
 
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John/castelli

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None of the above!
I talked to a guy an he said in plug my throttle position sensor I did and the problem stopped why would it stop if I unplug my throttle position sensor
 

dudeman2009

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None of the above!
I talked to a guy an he said in plug my throttle position sensor I did and the problem stopped why would it stop if I unplug my throttle position sensor

The throttle position sensor tells the PCM where the throttle plates are, it uses that value (plus a few others) to determine what the desired power from the engine is, it then makes adjustments to the ignition timing (by way of when the coil is energized) as well as fuel timing. Unplugging this sensor will cause the engine to go into a sort of limp mode, where fuel injection is reduced and ignition is ********. Unplugging this solves the symptom of the problem by changing the way the engine is operating. You will have very poor performance with the TPS unplugged as well as decreased fuel economy.

When you say none of the above, did you test any of it? Or because unplugging something fixed the symptom you decided that testing what was suggested is no longer needed because the 'problem' is gone.

I guarantee you that the TPS is just fine if there are no codes for it. The problem is with something else.

Backfiring occurs when large amounts of unburnt fuel suddenly ignite while both intake and exhaust valves are open. This causes a sudden explosion of fuel and air that travels both down the exhaust and back through the intake. This can be caused by a few things, poor or no spark, delayed spark, valve timing/cam issues, excessive fuel or lack of air. Cam/valve issues are rare in stock engines. Too much fuel has other noticeable symptoms. Lack of air is a possibility and can be tested by checking the air filter or just removing it. Poor spark is the most common, even ahead of poor airflow. Spark can be tested with an inline spark tester, the color of the spark in the tester indicates the 'health' of the spark. Another method to test is to measure the coil with a multimeter, and visually inspect the wires/ distributor cap and rotor. If there was a control system problem, it would throw a code 85% of the time, there are few control system problems that won't throw a code.
 
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dapepper9

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The throttle position sensor tells the PCM where the throttle plates are, it uses that value (plus a few others) to determine what the desired power from the engine is, it then makes adjustments to the ignition timing (by way of when the coil is energized) as well as fuel timing. Unplugging this sensor will cause the engine to go into a sort of limp mode, where fuel injection is reduced and ignition is ********. Unplugging this solves the symptom of the problem by changing the way the engine is operating. You will have very poor performance with the TPS unplugged as well as decreased fuel economy.

When you say none of the above, did you test any of it? Or because unplugging something fixed the symptom you decided that testing what was suggested is no longer needed because the 'problem' is gone.

I guarantee you that the TPS is just fine if there are no codes for it. The problem is with something else.

Backfiring occurs when large amounts of unburnt fuel suddenly ignite while both intake and exhaust valves are open. This causes a sudden explosion of fuel and air that travels both down the exhaust and back through the intake. This can be caused by a few things, poor or no spark, delayed spark, valve timing/cam issues, excessive fuel or lack of air. Cam/valve issues are rare in stock engines. Too much fuel has other noticeable symptoms. Lack of air is a possibility and can be tested by checking the air filter or just removing it. Poor spark is the most common, even ahead of poor airflow. Spark can be tested with an inline spark tester, the color of the spark in the tester indicates the 'health' of the spark. Another method to test is to measure the coil with a multimeter, and visually inspect the wires/ distributor cap and rotor. If there was a control system problem, it would throw a code 85% of the time, there are few control system problems that won't throw a code.

I'll have to disagree on the bolded. In my experience the TPS rarely throws a code while often being a problem. My own truck has evidenced this over the last month and a half. Swapped a larger throttle body on and afterwards the tps failed causing the truck to hold a high idle from 1500-2500rpm and consistently. However quick tap of the throttle in park or neutral as long as i got it past 3k would reset it to a normal idle.

But back to the problem. Plug the tps back in and find the real issue. Spark is the likely issue however low fuel pressure can cause this as well. Spark has been explained but low fuel pressure will cause the same issue if the injectors aren't firing properly. Liquid fuel doesn't ignite, the vapors ignite. If you're dripping fuel into the cylinders some will burn but not all and it will drip down the exhaust where it hits the cat and begins to ignite. However, I'd suspect spark.
 
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John/castelli

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I did check all the above an it all was fine! Do u think the throttle body is bad!?
 

dapepper9

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Throttle body itself no. It's a mechanical piece thats only movement is about 80 degrees of rotation in one direction. However it's possible that a throttle position sensor is bad. I might consider that. Any parts store will have one for $30. However if that fixes it, take the part back and return it for one with a lifetime warranty instead. It'll cost more but much more reliable
 
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