Car lunging at highway speeds

[RiceyRS]

When I'm driving at say 55-65 mph and press down on the accelerator just a little the car starts lunging the rpms start jumping up and down from say from 1800-2200. Any thoughts on what's going on?

[Guardsman]

Possibly Torque Converter locking up and unlocking repeatedly? That's my shot in the dark.

[Jeff Pristelski]

I was gonna say you need to shift... then I noticed you're only at ~2000 ;)

[sped214]

I've been having the same problem for months now. I've scanned it, autotapped it till I'm blue in the face. The tranny and the engine both come up clean (no errors or codes). It's driving me crazy. My off the line speed sucks too. I think it's the same problem. If you find out what's causing it, let me know what it is. What a PITA.

[camaro_zach]

this is the same prob i had, only mine worked it self out. this is EXACTLY what i had. i reset the comp and let it work itself out. i messed up my IAT but i dont konw what you could of done to cause this.

[TheV6Bird]

Have you checked ignition? I remember when I first got my car, on 45-60, the whole damn car would start to shake, rattle, and roll! Then whe I stepped on the gas and the trans downshifted from 4th to 3rd and the RPMs went to 3000, the shaking went away.

Took it to the shop, and the #3 plug was fried. All plugs and wires replaced, problem solved :cool:

[EyeOutThere]

Could be a bunch if things.

If you haven’t changed the plugs/wires in a while I would do that.

My friend was having the same problum and it turned out to be a loose plug.

[whtefbrd96]

This comes up alot and happens to me also i replaced my plugs and wires it wasnt that. Somebody replaced their egr valve and it fixed the problem. i havent gotten around to doing it yet doesnt bother me enough for that.

[Brian Dieckman]

The Haynes manual says "speed surging at high speeds" is a result of the fuel system. I'm guessing they're talking about poor pressure.

Might check that while you're under the hood.

[knowledgefreak]

first thing i would check is a problem with your plugs or wires, either loose or bad or a burn spot on a wire somewhere.

That will cause the lunging on the highway. Check for a loose boot/bad crimp job if you replaced the wires or burn on a wire.

[RiceyRS]

Thanks for the replys, I'm gonna change the plugs and wires this week, and probably bypass the egr and hopefully that will work.

[sped214]

Good luck. I've changed the wires/plugs and tried the EGR bypass by placing a metal plate between the egr valve and the pipes that connect to it, but still have the problem. Let me know if that works for you...

[sped214]

Hey, RiceyRS... Did you ever find anything out on this?

[RiceyRS]

Well I don't know exactly which thing I did that actually fixed the problem but it seems to be gone now. Basically what I heard from the dealership when they replaced the rear end and the fuel pressure regulator, they reprogrammed the computer but forgot to calibrate the torque converter, so I had them do that. And I've also replaced the plugs (2 weren't in the best shape) the wires, change the pcv valve (the old one was stuck, which is what caused the "tar" inside my throttle body, so I cleaned the throttle body, and I also changed the trans fluid and filter, and ran some injector cleaner through the car, and I know a few other thing. So it seems to be working now but I don't know which one fixed it.