[PacalFox]

I have a 1997 RAV4 that lately has been having difficulty keeping the idle rpm high enough (at least 800 rpm I would say) when starting. I have looked in this forum and other places and I see that the most recommended solution is to clean the idle air controller valve and the throttle body. But given the way my RAV4 symptoms show, I suspect it may be something else. So I'll explain how it happens.
When I start the engine, sometimes (not always) the rpm go all the way down to a very low level where it struggles to keep running or it just dies unless I put my foot on the accelerator. Often it just stays between 300-500 rpm. When I turn the air conditioner on it does not increase the rpm.
After a few minutes, when the engine gets warmer, if I push on the accelerator and release it, then it stays at a higher minimum of around 1000-1200 rpm, which looks to me as the normal rpm for a motor that is still warming up. If at this point (when the right minimum rpm are being kept) I turn on the air conditioner, then it does respond and the rpm go up 100 or 200 rpm. I don't think that the rpm would go up to the correct level by just letting it sit there and idle. It happens after I press on the accelerator. But I have to let a few minutes pass, otherwise when I release the accelerator, it goes all the way down and almost stalls.
Now, if the idle air control valve had difficulty turning due to being dirty, I wonder if the malfunction wouldn't happen all the time. This problem seems to be temperature related. Even if it normalizes when the engine warms up, the other day the weather was a little colder in the morning and when I went to start it, it worked fine from the start. Maybe it was just a coincidence, I haven't tried again because now the days got warmer. If you have any ideas about this I'll appreciate your advice.

 

[OldRav4]

Have you checked your throttle cables to see if they're stuck?

 

[PacalFox]

Have you checked your throttle cables to see if they're stuck?

The cables are OK, I checked them. I guess if I had the opposite problem, with the RPM "sticking" too high, then the cables could be the problem. But in this case the idle RPM goes too low. I did notice that there is a little vacuum diaphragm that puts a "stop" to the throttle lever. I did try to watch if the position of the lever changed when the RPM have a tendency to go lower but it was hard to tell. I didn't look further because I thought it was somewhat related to the idle air control valve and not the position of the throttle lever, but maybe I should look into it further. Something that I can do is to see what happens if I disconnect the vacuum hose from that little diaphragm (if that's what it is called) and see if the throttle lever moves to a lower RPM position. If that is the case, it could be that the diaphragm is not getting enough vacuum. Well, thanks a lot for your suggestion. Even if it is not that, it made me think about it a little more. I'll do the test I mentioned above and post the result. Thanks again.

 

[OldRav4]

Yeah man, no problem. Happy to help.

Also, you should check if there are any loose vacuum lines in general.

I know you mentioned that many have suggested the IAC and throttle body. Maybe give those a good cleaning? It's a relative quick, easy, and cheap job.

Other than these, I can't think of other possibilities right now.

Good luck dude!

 

[96 Rav4]

My '96 was doing exactly the same thing about 3 months ago. I know you've checked this already but...
My throttle cable had slop in it so I tightened it. It didn't make any difference at all for about 2 days then the startup idle went back to how it should be. CPU took time to recognize the change?
This could be coincidental but I also ran some Marvel Mystery Oil through a tank of gas. I don't know which made the difference but it's been ok ever since.

 

[FixIt]

Have you cleaned the throttle body and idle air valve as recommended by others here? I would do that first, then ask detailed questions if that doesn't solve the problem. I suspect it will. I have corrected many idle issues by cleaning.


When the engine is started, the PCM commands the idle air control valve to a programmed position that the engineers know will keep the engine running with a new, clean throttle valve. Once it is warmed up, another program is used to keep the engine from stalling hot.


The engineers did not account for real world accumulation of gum and varnish from crankcase blowby, so that is why this is a common thing that happens as a vehicle ages.