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ignition pop???

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Old Nov 27, 2008 | 04:46 PM
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nintey4f150
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From: south jersey
ignition pop???

hey.. i have a 94 f150 302... driving around normally everything seems to be ok but when i get it on it a lil bit and the rpms get higher there is a popping noise and it does it more then once.. my buddy's first reaction was he said it has something to do with ignition mayb cap and rotor.. just wanna hear what you guys think
 
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Old Nov 27, 2008 | 06:16 PM
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Is it a back fire? Does it only under load or if you give it some gas siting still?

"pop" "pop" "pop" "pop" every time anything above a idle? always matches engine speed?

Where you "hot rodding" it just before it started?

If so it sounds like it might be a burnt valve, but may not be that serious so don't panic, at least not until we hear more.

Need more info, how many miles on motor? missfire perhaps? What is the age condition of the cap/rotor/wires/plugs? does it sound like its on the intake side? exhaust side? Motor have a lot of valve train noise, lifter "tick" or "clatter" sound when it runs?

Can you record the noise and post in on you tube?
 
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Old Nov 27, 2008 | 07:43 PM
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the motor has 230,000 miles on but runs good.. cap, rotor, and wires were replaced in the summer... its doesnt do it sitting at idle but it does do it under load at full throttle and in higher rpms and its pop pop pop pop
 
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Old Nov 27, 2008 | 07:57 PM
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When someone complains of a pop pop pop sound as you describe its usually a burnt valve causing it. The "popping" sound is the compression rapidly leaking through the fairly small opening burnt into the valve itself and or valve seat where the damage occurred. Pops every time the piston hits tdc on the compression stroke, at an idle or no load condition it is sometimes not heard but still leaks.

I'd probably start with a compression test, if nothing else to eliminate that as the problem.
 
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Old Nov 27, 2008 | 09:02 PM
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The pop, pop, pop at and above idle is a blown spark plug... Trust me this is a bitch i just had to ez out 2 of mine after they blew out. Orginal owner used autolite plugs and they rusted away to nothing
 
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Old Nov 28, 2008 | 09:52 AM
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i dont think its a spark plug.. the truck runs fine driving normal but under full throttle is when it pops
 
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Old Nov 28, 2008 | 10:08 AM
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Maybe the timing is off.
 
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Old Nov 28, 2008 | 12:55 PM
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I let my son put new plugs in his bronco, was standing next to it a few days later while he checked the tranny fluid.
I noticed the back plug on the drivers side moving around as it idled standing there. Didn't really make any noise but you may have one really loose, but only making noise under load or higher rpms.

Made him check them all, two more where loose!

Surly wouldn't hurt to take a minute to double check.
 
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Old Nov 28, 2008 | 04:09 PM
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only under load.. but its gettng worse now i can her at lower rpms
 
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