What causes the engine to lurch?

[Tim OLeary]

2002 ST Sometimes when I press the gas at about 2K it feels like I ran over something small. I feel these little bumps. Otherwise runs idles smoothly, accelerates smoothly, not throwing codes.
New plugs and coil.
Thanks

 

[DILLARD000]

Did this bump at 2000rpm start immediately after changing the Plugs+CoilPack or was it there before?
What Plugs+Gaps\Wires\CoilPack did you use?

 

[Phil Frady]

Mine will do that only when I’m in drive through or at a light so I know I need to clean my IAC, but at 2K rpm specifically it may be TPS.

 

[swshawaii]

Good point on servicing the idle air control valve. Should be considered routine maintenance as well as throttle body cleaning and spraying the MAF filaments with electrical contact cleaner or MAF cleaner spray.

Faulty TPS or connector will almost always throw a CEL and p0122/1122 trouble codes. At least that was my experience when I had TPS issues and installed mine wrong. I know there are only two possible ways to install the TPS, and I got it wrong. Also need to be very careful removing the overly Loctited Philips screws. If the heads strip it's a PITA to repair.

 

[DILLARD000]

Yep, replaced those phillips head screws with hex heads when my TPS went out several years ago.

 

[Len Jorgenson]

Are you in a parking lot with speed bumps?

 

[Tim OLeary]

I used the correct plugs plug wires and coil pack. I will need to look up the part#'s but it was a few months ago. I had changed the plugs, plug wires and coil pack cause it was way past due and also to alleviate the problem.

Are you in a parking lot with speed bumps?

speed bumps! That was how I was going to describe it to the forum. (It isn't those reflector lane markers either!)