Lexucan

Hey guys,

I need help.
My ES has been acting funny the last couple of days. Out of the blue it intermittently started hesitating when I press on the gas pedal from a stop. And now sometimes when I start the car, it also intermittently revs up to about 2,500 rpm for maybe 8-10 seconds and then slowly drops to 750 rpm (this after the engine has already been warmed up). Other times when I start it, it revs to 2,500 rpms then drops quickly to 1,500 rpms then shoots back up quickly to 2,500 rpms and back down to 1,500 rpm, etc. It will do this up down up down thing 3-4 times and then finally stablizes at about 1,200 rpms and will not drop down to normal idle level (750 rpm).
Edit: Forgot to mention - sometimes the rpms drop so low when I come to a stop that it nearly stalls if I don't keep my foot on the gas to keep the revs high enough.

Any ideas (Phoenix???) what might be causing this or what to check?
I had it at the Toyota dealership yesterday and they couldn't pinpoint the cause as the symptoms seem to come and go and there is no check engine light coming on either so it is something that isn't monitored by OBD1.

Any help would be appreciated!

92ES5sp

Lexucan, I had a similar problem, and couldnt pinpoint it, but when I did my valve cover gaskets, I cleaned the upper intake plenum and the IAC valve and re checked for vacuum leaks, and the problem disappeared. Only from a warm start up did it do this weird idle behavior, and it would take 3 or 4 red lights for the IAC to kick in and keep the RPMs at 700. From a cold start up, it was fine. Hope this helps.

Lexucan

Yeah, thanks 92ES5sp. This gives me some place to start looking. Couple questions for you:
Did this weirdness start as suddenly for you as it did with mine? Like, I drove mine to work last Wednesday morning and it was fine. At noon I drove it again to get lunch and it was fine. Then after work, after five minutes on the road, it started acting up with the low idle and acceleration hesitation and then the crazy up and down high idle behavior after turning off the car and starting it again.
Also, did yours exhibit both of these symptoms intermittently? It seems mine starts and runs ok sometimes (usually from a cold start) but then does the weirded out thing later on.

92ES5sp

Sorry for being unclear. Ive havent had a hesitation problem, just a low idle all the time except after sitting overnight. I knew when it was going to act this way because it went hand in hand with the 2500 rpm initail idle, then it would creep down pretty quick, and before it was even up to temp, the idle speed was very low, like 400 or 500 rpm. Then like i said, after a couple red lights it would go away. Its kinda hard to explain in text.

FWIW after i put my upper plenum back on it ran fine, only the rpms were jumping up and down pretty rapidly. The engine would not idle at all, just raaar raaar raaar..... I cant tell if this is similar to your idle behavior but I found 2 small vacuum lines I left off and its ran fine since putting them back on. And for future reference, when you unplug the IAC motor, it does the same thing (the surging) I unplugged it to verify it was working. To answer your question about the engine acting up suddenly; no it didnt, it progressively became worse, and happened more and more frequently, but never from a cold start. It was very predictable.

So I would start by checking/cleaning thr IAC valve (it was very very dirty) and all of your vacuum lines as there is quite a few of them. Or pull the upper plenum off, clean everything, and change the plugs while youre in there. Good luck

Lexucan

Well it sounds like mine is doing something fairly similar to what you experienced. high surging RPMs after a warm start, followed by very low idle. And then going back to running normally. And always ok from a cold start.
I'll definitely be checking out the IAC valve as a first step. I cleaned the throttle body about six months ago. How often on average would you say that needs to be done? The plugs were replaced at the same time.

Thanks AGAIN for your input, 92ES5sp !

I'd also sure like to get Phoenix's take on this issue.....where is the almighty ES guru when we *I* need him?

esucaris1

Lucky for me I have a extra parts from my jdm... hopfully I will never need them but ya all know the history of my car...

BadViper22

looks like 92ES5spd took care of ya Lexucan, but i'll throw in my 2 cents just for kicks. One method i used to eradicate my idle problem was removed the intake from the throttle body and started the car, i kept it at and idle with my finger on the throttle, then i took some very lovely CRC carb cleaner and shot it right down the throttle. While i had that going down my intake i pushed the throttle down all the way so my engine sounded like it was in the 5500+ rpm range. After that, never had another idle problem again.

huerdo623

a few months back I remember somone else having this problem and they fixed it by removing the fuse to the ecu for about 15 to 20 secs to reset something

Pheonix

vacuum leaks & clean the intake, including the IAC.

Lexucan

Thanks for the input, guys.

Well, the IAC valve was cleaned on Thursday (at my request) at the local Toyota dealership. I didn't have an appointment but they said they'd try to fit it in to their schedule.
Afterwards they took it for a very short test drive and reported that it seemed to be running okay.
So, I get in the car to leave the dealership and the car won't even start! It was exhibiting the same symptom as before - starts up fine when cold and runs okay for a little while but once warmed up it is very hard to restart (takes 5-10 minutes usually to get it going again) and once restarted, the idle is all over the map, like up to 2,500 RPMs or down as low as 150 RPMs.
One thing I don't know is whether or not they tested the IAC to see if it was actually working. Since I took it there to specifically have them clean the valve, they may have done so without even testing it as they did the job kind of in between their other service jobs.
So, I guess the next logical step (since the car is still at the dealership) is to find out if the IAC was actually tested, and if not, get them to do so. I may have a nice clean but defective valve...
And checking for vacuum leaks sounds like a good plan too!

BadViper22

How much was it for toyota to clean your iac?

Lexucan

It was about $70
I was planning on doing it myself after work on Wednesday with the help of someone who has some tools and the space to do it, but at the last minute he bailed on me. So, I had to drive the car to work the next day in the same condition and it was driving REALLY bad (nearly died at least twice). I had no choice but to take it to the dealership which is not far from work.

esucaris1

any news yet what did toyota come up with???

Lexucan

Actually, yeah. I got the car back yesterday afternoon and it is running fine again.
It wasn't the IAC valve after all. Turned out to be the ECT (engine coolant temperature) sensor. It was giving false voltage readings to the ECU and fooling it into thinking that the engine was still cold, even though it had already reached normal operating temperature. So the ECU was retarding the timing and injecting lots of fuel into the cylinders. That is the reason it ran ok only while it was cold, but once it warmed up after five minutes or so, it started to act up and wanted to stall all the time. The Toyota service advisor got a hint last week which eventually led to the ECT. After the IAC valve was cleaned but the car would not restart, he could smell gasoline both at the engine and the tailpipe which indicated it was really running rich. So he guessed that maybe something like the ECT sensor could be the culprit, and sure enough it was.

esucaris1

Excelent information... you never know when info like that might come in handy...