I have seen this question asked and people are changing plugs, fuel filters, air filters but no one is changing their coil packs insulator boots. These things start going bad at around 50k miles. You may have one bad and the spark is jumping and it will cause a momentary miss and a jerking action which will puzzle people to spend unnecessary money. The boot insulators are $4.99 at AutoZone and the part# is CP003 and has a lifetime warranty so after 50-70k miles you feel the same symptom replace all of them and get new ones. If it’s the case where this is not your problem you can return them and get all your money back but I guarantee that if your Mustang has these symptoms and you have around 50k miles and never changed these boots this will fix it.

 

I had a coil pack go bad on my f150. man it ran really bad. Pretty easy to change unless its on of the rear 2 on the drivers side.

 

hey solgo, a coil will cause a dead miss, it's either good or bad but a boot will cause a random miss and is most common is while Accelerating. Glad you found your problem.

 

awesome thanks for the heads-up!! i'm nearin' that 50k mark, just waitin' for sumthin' to come up, lol.

 

Well the problem was only under acceleration, but it was the coil not firing properly.

 

Will a bad boot cause the car spark knock when u get on it?

 

spark knock??

have you checked your plugs and made sure they're tight, I had one knock and thankfully caught it before I got the dreaded "plug blowout" syndrome. A bad boot will cause it to buck and jerk especially upon acceleration.

 

03GT have you got a sound clip of your Cherry Bomb Extreme mufflers, would love to hear them!

 

I have had the same issue but it has only done it like once a month and only when the engine is still cold. Does engine temp affect whether the boots go from being good to bad?

 

You may have a boot going bad, I had the jerking constantly from lightly to hard acceleration but nice and smooth at idle, keep in mind that the boot took place of the wire set and when the wires were bad it was actually the boots deteriorating but to the naked eye it looked good. The boot needs replacing the same as if you were changing a wire set from the older cars and is a part of a tune up.
Your issue is not so bad but will get worse and will do it constantly so when this happens change the boots and remember with a lifetime warranty on the boots AZ will not hesitate to return your money.

 

BTW, thats how they all start off and then we just dismiss it as well maybe it was all in my head lol.

 

You can also test it by putting it under a load, manual transmission cars; while driving your car about 25mph put it in first 4th and gradually press your gas pedal and if you get the bucking/jerking action boots will be a suspect.

 

What about on an automatic??

 

what you want to do is put a load on the motor, cruise about seventy and on an incline slowly press your gas and if you don't get any bucking then your ok.

 

My 01 GT has been jerking a lot (automatic trans), usually when i accelerate, but i can usually accelerate out of it and it goes back to normal. Im guessing its what the first poster said? The coil pack insulator boots, which I assume are what attaches to the spark plug (yes im a newb).

Also when im at a low gear/rpms and i accelerate but let go of the gas (usually in traffic) I get a really hard jerk, almost like a really hard downshift. Not sure if thats normal.

 

Yes but make sure your plugs are gapped correctly because if they're not you will get the bucking/jerking as well, I set mine at 53 thousands, The coil paks are only good or bad. A coil pak is never "going bad". If you notice that if someone replaces a coil pak they always replace the insulator boot so of course they think the coil pak fixed it. I believe it's normal if you release the gas before it changes gear and when you let off it lunges foward.

 

yea when i had put in the plugs i checked there gap, but its time for them to be changed anyway

how much do the coil pak insulator boots usually run?

 

The boot insulators are $4.99 at AutoZone and the part# is CP003 and has a lifetime warranty

 

sweet dude thanks

 

your welcome sir

 

I bought an 8 pack for 34.99 at oreilly, put new copper core plugs in and the miss is gone. Too bad I spent 500 on a torque converter and shift kit for (probably) nothing. We just won't tell the wife. Thanks a million.

 

I'll try that. I will also spare my wife the details. I was going to replace the torque converter but this seems like a logical, less expensive way to go.