Stxalldway

Hello everyone, I was wondering if you could help me. When I'm driving and suddenly need to hit my brakes and then go to go again, there is a hard jerk. Keep in mind, when applying brakes I never fully stop. The hard jerking only happens when I go from a hard slowing motion to proceeding again. A friend says its a safety feature so the transmission isn't in a bind a breaks. If I allow the truck to roll for a second then it won't do it either. Anyone have any idea?

Summers22

iTrader: (2)

You need a tune up of new plugs, either new COP's or rebuild the current ones with new boots and springs, fuel filter and clean your MAF and throttle body (remove throttle body for best results). My truck did the same exact thing. After a tune up, it all went away.

Stxalldway

Thanks but the jerk I get is one hard thud like its caught between neutral and gear. I had the issue you're talking about and did all those things and it cleared up but this is a transmission issue. Again, when I feel the thud or hard jerk it's almost as if it's caught between gears. Does not happen any other time

bwFX42006

Summers did you find it was easier to rebuild the coil packs or just replace them? They're like $70-$80 a piece arn't they? My friend just had his plugs replaced in his 2006 FX4 SCAB, but he's only replacing coil packs as he goes...it seems to be working for him replacing one at a time because of the cost, but I prefer to do things all in one shot...if I can afford it at the time

screamineagle

I wouldn't say that replacing the boots and springs was "rebuilding" the COP. The "coil" part is not serviceable. However, replacing just boots/springs is an option, more times than not, I have found the coil itself to be the fault of a misfire.

bwFX42006

So with 85,000 miles...do you think it would be better to find the source of the misfire instead of changing all the plugs? If it's just a COP that's gone bad, I would rather replace that than all the plugs until it warms up outside. The average temperature for this month at home here has only been 6 DEGREES!

GooseAbuse

Might sound kind of stupid fellas, but could this be a U-Joint issue? have you checked your U-Joint?

Summers22

iTrader: (2)

I would take it to a reputable transmission shop and have them check it out.

Summers22

iTrader: (2)

I rebuilt mine with new springs and boots, then when the issue was still there, replaced the plugs and COP's with Motorcraft. It was the plugs causing the issue. I bought a set of 8 COP's from a 2012 Mustang that had 7k miles on it for $120 for all 8.....

BUCKSHOT

X2, that would be my guess from the OP's description