My truck (details in signature) has been having a problem lately.

When the truck drops into overdrive, it starts to buck, almost like it is misfiring. It happens between 50-70 mph. Makes passing on the highway almost impossible.

I have a receipt for the plenum fix when I bought the truck. I looked into the throttle body, and it is clean and shiny. The truck got new plugs, wires, cap, rotor, pcv valve, and air filter about a year ago.

I made sure to route the plug wires according to the TSB on here.

Doing a search leads mostly to the plenum, but it has been fixed on this truck.

It only happens in overdrive. I keep o/d off unless on a stretch of highway.

Any suggestions are greatly appreciated!

 

Do the rpms change when it's doing it?

 

RPMs stay consistent, no noticeable change on the tach.

 

Did you also do something about the cat and o2's after the plenum fix? And was it fixed with an aluminum plate or stock?

 

Feels like a miss, because it IS a miss..... Pull your plugs, and have a look at 'em.

 

had the same problem with my V10, plugs and wires will do the trick, if it seems like a slight pulsing, then it could be the throttle position sensor, they are common to go and I have had to change mine as well, the TPS is feels more like the TC locking up and disengaging often, if it is rough "bucking" then definitely the plugs/wires need to be changed

 

Not sure on the cats and O2 sensors. They appear to be stock. The new plenum plate is aluminum.

These plugs and wires have less than 10,000 miles on them. I will pull the plugs this weekend and see what they look like. They are copper Champions.

Wouldn't bad plugs/wires make the truck run poorly all the time, not just in o/d? Also, I did the plugs and wires in October 2011, and it's only been doing this for a few months.

 

Pull the upstream O2 sensor out and tie it up out of the way. Take it for a drive and seee if it is any better. It will sound as though you have an exhaust leak (becasue the O2 port is open).

If it runs better, this is indicative of clogged cat - the result of the plenum having been bad.

Check it out and let us know what you find.

 

@ Bob5151. You should know better after being a member since 08 about the cat and o2's. Do like GD stated and see if it runs any better.

 

I should know better. Hey, in my defense, I did use the search function, and even posted in the correct section

I am going to pull the O2 sensor before leaving work tonight and see how it runs on the way home.