Shuddering under acceleration

[FordF-SuperDuty]

I was driving to work today and about 5 or so minutes into the drive under acceleration the Bronco would shudder horribly and not want to accelerate. This both happened going up a hill and coming off a stoplight, but it will cruise fine. Idle was good, no CEL, and all gauges good.

Edit: Forgot to add in park it doesn't want to idle but in drive it's fine.

 

[LEB Ben]

IAC issues or maybe a clogged cat would be my guess.

 

[FordF-SuperDuty]

IAC issues or maybe a clogged cat would be my guess.

How would I check for a clogged cat? And where is the IAC again, it's under the black plastic thing by the throttle body?

 

[LEB Ben]

Outside of physically removing the cat, you might smell more exhaust, black soot being expelled, rougher idle, loss of power, loss of mpg's, might even hear a rattling sound from your exhaust. Outside of that, I remember reading that you could remove an O2 sensor upstream and if performance changed, you knew a cat was bad...but I dunno if that's true or applicable.

 

[Skandocious]

You can check for a clogged cat by measuring the temp of the exhaust both before and after the cat. A clear cat should show temperatures that are roughly the same.

 

[5.0Flareside]

laser thermometer... read the temp before and after the cat...

 

[73F100Shortbed]

If you remove the 02 sensor upstream it gives the exhaust a place to exit. If it gets better then cat could be clogged. Or you can unbolt the y-pipe. Less work would be to measure temp like suggested.

 

[FordF-SuperDuty]

It was that dang MSD Blaster coil!!! Good thing I saved my old coil, it also feels like it has a bit more power now.

 

[73F100Shortbed]

Glad you that fixed up quick. Sure beats replacing the cat.

 

[FordF-SuperDuty]

Glad you that fixed up quick. Sure beats replacing the cat.

If it was the cat I can sure as heck guarantee you that a cat would not go in its place.

 

[Truckin4life]

Glad you got it figured out, had i known you had a MSD coil, that would have been my first guess!!!!!!!!!!!!

 

[LEB Ben]

If it was the cat I can sure as heck guarantee you that a cat would not go in its place.

No emissions testing on that rig????????

Glad you got it figured out, had i known you had a MSD coil, that would have been my first guess!!!!!!!!!!!!

Maybe not my first guess, but I know the guys over on FSB are having all sorts of problems with MSD coils for a while now, after they perform their 6L tune up.

 

[FordF-SuperDuty]

No emissions testing on that rig????????

Nope!!! The truck seems to run smoother now to even before the problem started, I used to get a bump sort of when laying off the throttle and it seems to idle better too.