well i have asked this question before and really didnt get a straight answer from anyone so here i go again.my car(auto) does this wierd thing when im coming to a stop. when im coming to a stop i can see my idle go up and down a couple of times and settle at the normal idling speed on drive.also it idles high(aroung 1200-1500) if i let the car sit for a while eaither at a stop light on drive or on park for a while. few months ago i had a MAF Sensor replaced too. did any of you guys had this problam before and if so what is the problam i am asking from you guys is bcus my mechanic really dont know whats wrong and you guys seem to have more knowledge.

p.s. before i had the MAF replaced it did 50mph at 1500rpm and now it does 50mph at around 1800rpm.

all my modding will be stopped till she is back to normal too. :-(

 

Have you pulled codes? It sounds like it could be a VSS (vehicle speed sensor) not functioning properly.

 

do the idle relearn precedure.
it's normal for AT car reving up and down when slowing down because the gearbox is down shifting.

 

my CEL light is burnt out or something but, I did pull codes and didnt get any. I actually didnt get any codes even when my MAF was bad but, I will pull out codes again.also its normal for AT cars to revs to move up and down when slowing down? Ive never seen a car doing this before. Its like im slowing down it goes down to 450 then come back up then again to 450 then come back up and settle down at like 500 - 600rpm.

 

...450rpm..that's too low. I was talking about around 1000rpm

 

^^^^ thats what i mean. what the hell is going on?? im desperate. im bet there are members here that can tell me but recently they are too busy with stuff to help someone with out a lot knowledge.

 

Do the idle re-learn and report back.

 

how about idle air control valve

 

If your cruising speed rpms are higher than they used to be, you could have a problem with the lock-up torque converter.

 

^^^^i really hope its not the lock up torque convertor because, it sounds expensive to do repairs on that. i will mess with the idle,vacuum and other stuff before i go to a torque convertor. but thanx scott ur write ups on detailing forum really helps. ;-)

 

If the RPM's rev up and down WHILE idling and NOT moving, it's most likely 99% the IACV. IF your idling at a high speed or low speed (450 seems very low at idle, idle should be from 850-1000 RPM) check the butterfly valve near the MAF, there's two of them, one should rev the engine and other one is for cruise control. DO NOT ALTER THE ONE FOR CRUISE CONTROL. When you pull one it should rev the engine. You'll need a small screwdriver or whatever tool to adjust it. Tweak it until your RPM's are at a reasonable level. As far as shifting down, then up then down on an auto transmission, it's normal. The gearbox is controlled by the computer so whatever your driving habits and such, it will replicate that. Remember it's a 4-spd auto so the shifting is more evident.

 

i really dont think you guys are understanding what i am saying. My idle dusnt move up and down when im not moving, its when im slowing down as a normal car would it stays at like 900rpm. Then when im almost at like 0-5mph it come down to like 500-650rpm( not 450 im sorry) then go right back up and come down one more time go up and comes right back up and settle at like 650rpms. This all happen when im slowing down to a stop not when im stopped. Hope thats more clear.

 

That is normal, the tranny is simply downshifting, although mine only goes back down to 700rpm aka idle speed.

 

HELP!!! I am having a somewhat similiar problem but not exactly. I have a 2000 auto. I was driving on the interstate about 2 hours away and about 30 minutes into it at about 75mph, the car jerks, the rpms shoot up from about 2200 to 4000 and stays there the whole time. It took 3/4 tank of gas for that one leg. At one point the needle would drop to about 0 and back up then down and up.

After the car was turned off once we arrived and then back on for the leg back. It was back to normal until about 1.5hrs into the ride it did the same exact thing, so I pulled over, turned the car off then right back on and it went back to normal again. However this time since it was normal for pretty much the whole trip it only took 1/4 tank of gas. Please someone tell me what the hell is going on and what to have done about it!

 

maf sensor

 

really dats normal? wow that is soo anoying. but wut ab8 me idling high after its been sitting at a long light?