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2000 Plymouth Neon Question: Backfire in Intake, what causes this? I need my car :(

 

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MechanicDIYintraining, Edgewood, MD, December 01, 2013, 18:03
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Heard a pop/thump once every week or 2. When the pop/thump happens, it is during acceleration. A few days ago the check engine light popped on after the car started to sputter along when accelerating and it started to do the poo/thump sound on and off, no specific pattern while in drive and with gas pedal down. This evening, I had my husband put e brake on to be safe, put car in drive while also pressing down the brake pedal, at the same time I had him accelerate while I watched and listened for the location of the pop/thump. It did it and it actually caused the intake hose, (the black rubbery accordion like hose) to move during the loud backfiring pop. What can cause backfire in the intake along with sputtering during acceleration? Fine when it is in park. Please help. Only during acceleration.

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    G. T. Service Center (4056 Answers) , Stephenville, TX - (254) 638-3236
    ProfessorG December 01, 2013, 18:42
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    Decarb upper end

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    MechanicDIYintraining, December 01, 2013, 18:44
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    Im a rookie, so can u explain!!! And I 4got to mention, there is gasoline lightly leaking from the fuel pulsation damper

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    ProfessorG, December 01, 2013, 19:04
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    I carry BG products and GM has a bulletin out for upper intake decab for misfires and backfires. There is a tool I use 'S' nozzle with chemicals.there is a different way with chemtool liquid w/toluene (not spelled right). An experienced mechanic can help you with this.

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    MechanicDIYintraining, December 01, 2013, 19:07
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    Ok. I appreciate your answer. Going to look into that

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    ProfessorG, December 01, 2013, 19:12
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    If you have questions just ask. I will not tell you how to do this yourself with no experience.

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    MechanicDIYintraining, December 01, 2013, 19:15
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    Im just asking the questions for my husband. He is the hands on guy with experience. He has done quite a bit. From timing belt replacement, head gasket, valve replacement, ect. Im not attempting to do anything. Just trying to figure out where to begin with this intake backfire. Can the backfire be caused by anything else that comes to mind? Fuel injectors, fuel filter, the pulsation damper, cam sensor, crank sensor? If he doesnt know how, or isnt comfortable, he will not attempt anything ! Safety 1st

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    ProfessorG, December 01, 2013, 19:19
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    An intake valve is not seated or carbon build up or both. Pulsation damper ? Or pressure regulator.

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    MechanicDIYintraining, December 01, 2013, 19:24
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    There is gasoline making the outside of the damper wet. The regulator is attached to the gastank, the one thats leaking, is up against the fire wall and connects to the fuel rail.

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    ProfessorG, December 01, 2013, 19:29
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    I know the regulator is part of the pump is why I asked, haven't paid any attention to the damper, have had no problems with them and forgot thy were there.

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    MechanicDIYintraining, December 01, 2013, 19:34
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    Hmmmm, I wonder if the regulator got messed up when a tractor trailer tire tread chunk on the highway , 2 days before the popping got really bad, went under my front end and banged up under fhe car before coming back out near the gas tank. Matter fact, I believe I remember hearing my husband say he saw, felt and smelled gasoline there too. I just asked and he said he did touch n smelled gasoline there and it looked like it may have been cracked. Wondering now if thats not the culprit.( Refering to the regulator) its a shame I cant post video and pics on here. I have some that would probably be useful

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    bmdouble December 04, 2013, 14:39
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    sounds like a lean misfire situation,what codes did you get? make sure you have good fuel pressure and that it's not dropping too much on accel.

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    MechanicDIYintraining, December 04, 2013, 15:18
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    Well, ive had the car sitting all this time. 2.5 weeks now. Ive only drove it to check it out around my neighborhood. Since I was leaking oil and was given codes indicating misfire in cylinders #2 and #3 we replaced the head gasket. Since 2 of the plug tubes were cracked bcuz of being brittle and working on car in very cold weather, I attempted a ride to junk yard this morning. Got a coil and better wires and tubes for spark plugs, and my pcv valve was rigged from my step father breaking it, so I got 1 of them with the line that is attached. Hooked it all up at the junk yard and it was idling much smoother. No backfiring. Just a 1/4 mile away from junk yard with all of those parts swapped, the check engine light came on, so I made a uturn and went to auto zone and went to get the CEL checked. Instead of #2 and #3 misfire, it gave me a P1390, timing belt skipped a toothor more. Aaahhhhhhhhh. Wondering if its because of the tensioner being rigged , which I didnt know my father and husband decided to do when it broke during a fix when the timing belt broke on me almost 2 years ago. Uugghh. So, it is saying timing is slightly off. But, its driving so nice. Im guessing it could come back if not fixed. Im working on getting it done. Just hard to believe because its riding better than ever for some reason. What are the dangers of it being off a tiny bit and driving it like that? Even though it feels great now with no more intake backfire

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