Pop Under Load

[BiminiBlueLX]

My car sometimes will make a ''pop'' noise under load, usually accelerating in either 2nd or 3rd gear. After heated up to operating temp it goes away completely. So if anyone knows what it could be (bad injectors, or dirty plugs, broken plug wires, etc.) I'd appreciate any help! I was lucky enough to catch this happen on camera one day I was making an exhaust sound clip.

Here's the video where the "pop" occurs:
YouTube - Mustang Backfire

 

[BK_CAULEY]

http://www.stangnet.com/mustang-forums/825033-pop-through-intake-miss-cruising-speed.html

 

[50sleeper]

Same deal

Same deal here,
No OBD codes at the moment.

 

[BiminiBlueLX]

Same deal here, been fighting it for years.

Mine is the worst when the engine is cold and it only happens under load. The first 5 minutes after I start my car and leave my driveway it will studder and pop anytime I give it over about 50% throttle at under 2500 rpms or so. After the car is up to temp its just barely noticeable and won't happen all the time.

Over the years I've put in a 190lb Walbro, new fuel filter, new plugs, new wires, reman dizzy, new timing chain (old one was very loose), reman injectors, cleaned EGR and tested solenoid, replaced vacuum hoses, checked fuel pressure, new FPR, new ECT sensor and new ACT sensors, replaced gaskets on upper intake, new balancer (verified TDC), checked timing again and again, checked rockers, pushrods.

Got a killer deal on a A9L and MAF and didnt change anything from when I was speed density. No change in symptom.

My car is doing that same thing. It only happens on cold starts and under 2500rpm with anything around 40-50% throttle. Once the car is warm it never does it, so I don't know what it really could be except maybe just extra gas from the initial start up being burnt (since the cars run rich from start up to heat up quicker). Some days I can start it right up and pull hard down my street with no popping at all.

Seeing that you've done everything mentioned above, I will start with the plugs, wires, and make sure the MAF sensor wiring is plugged in tightly. Then if that doesn't work, I'll move to the fuel system and see what can be done there. Thanks for your input.

 

[50sleeper]

Tests

Yeah I'd pull codes too if you haven't already (I current have no codes).

I've also done a cylinder balance test and a compression test both came back looking good, you may want to do one or both of those also.

 

[302mustanglx]

try swaping the sparkplugs 4 new motocraft i had the same isue and it was foulsparkplugs. also look at night for wires arching. check ur wires 4 burn or rip ones this all can make a affect on this noise