Does your 3.4 auto do this? Weird cruising rpm's

[EricHartley]

Hey guys, So I posted a little while back about a tps issue and have now replaced my tps. But I'm still having this issue on my 99 4runner limited with the 3.4 v6 auto. I noticed it was doing something funny on the highway the other day.*

When cruising at a 80km/hr or over and I let go of the gas the rpms drop like the should, but then they drop further and then pop back up again. And I can feel it jerking the truck a bit when it does this.*

So I'm wanting to know if you guys have any thoughts as to what this could be? Is it normal? Does your 3.4 auto do this?

Here's a video of what it's doing*

4runner 1999 - YouTube

 

[Troybylt]

Check light on?

Does it hunt like that in park position?
What if you take the RPM to 5k in park and just let off immediately?
Does it die?

If your driving in second and take it up to 5k and drop out of gear (bump to neutral) Does it die?

I was having an issue with my 5speed similar to this if I revved too high and suddenly took off load it would die. I had Codes p441 p442 p446 if I recall correctly all of them read as charcoal canister vacuum leaks or fuel tank vacuum leaks. You know what it ended up being? Up in the engine bay there is a little 2inch rubber hose that goes to some EGR type sensor. Must have knocked it off when I pressure washed all the mud off my engine. Another symptom I had was I could OCCASIONALLY smell fuel near the left wheel well when I would exit the truck after a drive of 20mins or greater.

 

[EricHartley]

I did have the CEL come on when the tps decided to kick the bucket, but it has now gone away since I have replaced the tps.

no it doesn't shunt (hunt) in the park positions.

If I bring it up to 5k in park and let off immediately its fine.

i have yet to try bringing it up to 5k in 2nd and bumping it into neutral, but i can attempt.

i will also check the lines near the egr.
thanks for the suggestions.

if anyone has any more suggestions, lay em on me cause im stumped!

 

[Yukon'99]

Did you ever end up figuring this one out?

I'm having very similar symptoms, anytime I let off the gas fully (unless really slow) the RPMs will decrease as normal, then quickly drop about 500 and immediately back up 500.

I replaced the TPS and since then I haven't gotten another P0120, however the symptoms persist. I also lubed up the throttle cable springs and adjusted the throttle cable. I'm going to adjust the kickdown cable tonight, and maybe disconnect the cruise control cable to make sure it's not getting hung up or something.

Any other things to try would be much appreciated.

oh ya, I have same 99 3.4L AT

 

[gamefreakgc]

It sound more like a vacuum leak or an idle control valve issue in the throttle body. Search both of those on the forums. I don't think it's coincidental that your throttle body sensor went bad and you are still having idle issues (which essentially is what this is). I bet there's more going on than just the TPS.