this is a culmanation of two years. two differnt toyotas. (4runner/pickup) both with the 3vze.. both would start fine.. they will idle up to 1400/1500rpm's. after the colld start cycle is over and it changes loops i get a random idle changes form 800 to 1600rpms. there is no method to this madness.. it will do it when ever if feels.. and will stop just as suddenly.. itll be fine for a week or a day and then boom its back.. this seems to be a commen problem.. both mine did it.. my pals t100 with the 3.4 did it.. alot of people on here seem to have it too.. any ideas?? you guys see alot of yotas so i figured youd be the guys to ask.. anything to do with the coolent line running through the TB?

 

TPS sensor out of adjustment.

 

TPS is fine..
its also not my HG.
or my temp sensor?
or my AC idle up..
or anything simple to check..
this is something mysterious..

 

i cleand the TB but didnt do the IAC.. anyone have a pic of it??

 

Three problems I know could cause it:
1) vacuum leaks. you need to actually check using some carb cleaner spraying around the intake and vacuum hoses.
2) If for some reason you've got an ECM for an automatic truck. if you have a manual tranny with an auto ECM the park/neutral signal is not input to the ecm and it thinks the vehicle in in drive/reverse. it tries to idle up and then goes to far. this happens in an endless cycle causing a surge.
3) I've seen a few O2 sensors cuase this. If you have a scantool take a look at the short term fuel trims and see if it is fluctuating rapidly from rich to lean.

Thanks all I got. Hope it helps.

 

Did you actually check the TPS adjustment per the FSM?

 

could still be your temp sensor.

i bought one (brand new, in the box) that was faulty.
got me to map out all my injection wires, and everyting else under the hood, only to check the water temp sensor last, and found it was failing. (2 days of that)

so, it may be a ground, or cracked wire, but the only way would be to check your sensors when its acting up.

also, just for fun, check every connection and make sure its secure, your grounds are good, wires are not to close to any plug wires etc.

also, your air flow meter may be dirty or fouled. or the potentiometer may just be worn out.
do you have any replacement afm's.

like the gremlin, you gotta be sneaky.

 

checked the TPS per FSM.. thickness gauges and a meter.. and just for kicks unplugging it didnt help.. my O2 is brand new and it didnt help.. all the vaccume lines are new.. changed those two months ago when i did my HG.. ( it was doing this before my HG too)
i havee to say it runs fine.. it is a dog but it has the same power as my old v6 and others ive driven.. but all have this random idle..

 

Just to make sure, did you apply vacuum to the port on the TB when you did the TPS adjustment?

 

low battery will also cause this symptom ... check it .

 

Hey,

I have a 90' pick up w/22re that does the same thing, during morning warm up, but only when the anti freeze is more then a quart or so low.

I always figured that the temp sensor was sensing in and out of submersion in antifreeze, top off antifreeze problem solved till low again.

I thought it was my low coolant reminder system, lol

Thanks Kiwi

 

like i said per FSM.. on my 4runner now and my old truck.. coolent level is fine.. air flow meter is good.. i have two of them and both give me the same result. timming was set to 10 when the belt was changed when i did my HG's and my light says its ok.. i work at a dealership and they have looked at it for me several times with a scan tool and double checked my inspections with no such luck. our head mech said since i never cleaned my IAC i should.. seafoam through the booster seems to clear it up for a while then it will creep back..
funny thing is i posted this thread friday after work cuz its been getting under my skin.. mostly cuz it seems to have an attitude.. prime example would be since i made this thread its been at the normal 800 +/- 50 rpms..

 

Does it just randomly go to 1600 or does this only happen after warm up and it just does not return to warm idle?

 

AC compressor kicking in to defrost? That will bump up the idle speed.
Corroded ground wire may cause intermittent problems. Check ground on battery and back of block ground wire.
Does thermostat have the jiggle valve to prevent air pockets?
Have you swapped engine control computers?

Just some ideas...

 

it will randomly got to 1600.. it wont stay there.. ill start it up.. fan kicks on. idles at 1500... warms up to temp.. and drops down to 900.. drive to work.. then sometimes it will be at 1500.. then i get to a stop sign and its at 850.. and then its beck too 1600.. and some days it will stay at 850 - 900 all day long. and then the next day it will do it for about half an hour. and then be fine again.. or not do it for a week or so and then come back.. totally random..

 

i dont have a belt on my AC so i think that take it out of the picture..
ill check my other grounds but the positive and negative on the battery are new.. as is the battery.. i even did the positive wire to the main fuse box upgrade.. brighter lights.. but thats it..
i do not have a jiggle valve.. but i havent heard and bubbles in my heater core.. and i also burped the coolent system with a coolent funnel.. (love those things) but that does not mean its air pocket free..
and i havent swapped engine control computers.. itd be nice if i had one..

 

thanks for all your suggestions and advice guys.. i hope something will come of this.

 

Is there any chance that your coolant temperature is too low.

A stuck open thermostat will allow the coolant to warm up when sitting still or going slow, but if you go down the highway the coolant temp will drop and the auxillary air valve will open back up and cause the idle to be high.

also, check the throttle and cable for binding. when it is idling too fast, try to manually close the throttle.

 

[QUOTE=jtlinna3vze;50747244]i dont have a belt on my AC so i think that take it out of the picture..[QUOTE]

Actually this could be your problem. When you turn the AC or defrost on there is a signal sent to the ECM to idle up the engine to compensate for the load. If there is no load then it could be idling the engine up, detacting RPM is too high and then trying to idle down. This would be a continuous cycle as there is no logic to tell the ECM the AC belt is not installed and teh compressor it not running. If your going to leave the AC belt off then you should disable that AC signal to the ECM. This could very well be your problem.

 

[QUOTE=bwhyit;50747353][QUOTE=jtlinna3vze;50747244]i dont have a belt on my AC so i think that take it out of the picture..well when its up too 1500 or 1600.. if i turn the heat on it will jump up the idle about 50 rpms? same as when the idle is at 850. itll go up to about 950/ 975 with the heat on.. but i never turn the AC on.. and u say it would be a continuous cycle.. the idle change is random.. hasent done it for two days now..
how whould i disable the AC signal to the ECM.. unplug the compresser???