h4vok

This one has puzzled me for awhile, but when the car is warm and im crusing along then take my foot off the gas and let the car deaccel the rpm's drop to 1000 then *something* kicks in and pushes it back up to 1500 causing a little jerk, then it goes back down to 1000 then back up to 1500, then back down then back up for the *third time* then holds it at 1500 until i press the brake to stop.

Like I said this only happens when taking the foot off and coasting either downhill or on a straight it doesn't matter, but some sensor or the ecu is pushing the rpm back up when it hits 1000.

Has anyone heard about this, or know what to adjust so that it can deaccel properly?

rlx101

so the car actually jerks? how is your transmission doing?

h4vok

it is a small jerk when it pushes from 1000->1500, the thing is it does it 3 times so you notice it, after the 3rd time it holds the revs at 1500

its not a transmission thing coz i had this before i put in a new one

mibearings

I'm getting a similar problem. My car sometimes will Jerk when I suddenly let off the gas.
I haven't paid much attention to the speed or rpm when this happens.
I do know that one of my O2 sensors is bad, so I will fix this and see if that fixed the problem.
-Is your check engine light on?, Mine is (o2 sensor). Have your system tested if your check engine light is on.-

ES3_Ray

its gotta be downshifting, but if it jerks, maybe your engine/trans mounts are shot or, maybe someone messed with your trans shifter cable maybe if someone did anything to your throttle body...

check this out.

http://www.toyotanation.com/forum/sh...045#post485045

rlx101

if its down shifting then why is going 1000-->1500--->1000-->1500rpm hunting for a correct gear? sounds not right.. may be something going on with fuel or air supply (or both)

ES3_Ray

see what happens when you have cruise control on, idk what it will prove, but try setting it to a low speed and go down hill. the cruise control should let off the gas simulating what you've done. maybe this will show you if its a trans problem or a throttle control issue.

llcoolpass

the little jerk is the fuel cut to fuel supply change

on a stick shift its far more noticeable.
are you holding gears on your automatic or something? othewise, it's in ''drive'' / 'd' right?

the effect might also be exaggerated as others noticed by the motor mounts. also have a knowledgeable tech look at the trans fluid level [its not checked using the same procedure as motor oil]

swifty562

jerking can be cause by mounts, tranny, or engine stalling out, etc

any engine light?
hows the battery?
transmission fluid?
how fast are you cruising? (are you using cruise control?)
hows the RPM on idle?
when was the last time ur clean your throttle body?

h4vok

well i know the rear engine mount needs replacing (its not completely wrecked just has a whole in the bottom of it)

even if the engine mount was good, this might supress the jerk i feel, but it doesnt explain why the the car is *searching* for a rev to cruise on, you know what i mean?

to answer some of the questions:
- tranny was changed about 1 month ago and has new fluid (and i like i said before i did notice this behavior before i changed the tranny)

- the speed i am going does not matter (mostly 60->80km/h) because when you cut the fuel the revs just drop in 4th gear (i really cant feel it down shifting) and as soon as it hits 1000rpm it jumps up to 1500, and does this 3 times before just sitting there at 1500 (it is weird)

- it could be a air/fuel ratio thing like someone said, as i have been running rich for awhile and still trying to get it smelling fresh again (changing o2 sensors tomorrow)

- i have no CEL coming up

- battery is new

- rpm on idle is 950 (adjusted on purpose to stop rough idle i get at 750)

- cleaned throttle body with Subaru upper throttle body cleaner 1 month ago

- yes my gear stick is in 'D' always

- ES3_Ray i have already adjusted my throttle cable

thanks for your input so far everyone

h4vok

hey dudes

thought i would post what has happened just in case someone else comes along with this same issue one day

but last night i changed my front o2 sensor and adjusted the AFM 5 ticks leaner with the battery off the hook and this (resetting the ecu) has solved the problem.

well not during the first drive, it was doing the same thing except it was alot more jerky, and when i went downhill it did it like 5 times, so yeah after a night's rest i was driving to work and i noticed when i took the gas off, the revs would drop to 1000, then push back up to 1500 and stay there! no more back and forth

so some resetting and re-learning was on the cards in my case

ES3_Ray

Im curious, what is this "adjusted the AFM 5 ticks leaner"? you can tweak the air fuel meter?? im lost.

swifty562

before this... did u adjust the AFM? by opening the black portion that sits on top with glue all around?

h4vok

swifty - yes i did, initially i tried 3 ticks leaner, didnt do much

so yesterday i set my timing back to 13*btdc (it was slightly retarded to smoothen my idle)
and then when changing o2 sensor i decided to lean it out even more because i was still running rich

ray - here
there is a better link out there somewhere, but i could only find this one in time for you

ivory98es3

iTrader: (1)

Have you thought about the possibility it's your EGR valve or position sensor?