4runner Idle Problems

My 2000 4x4 4runner just after it starts up tends to have a funky idle. It rarely goes above 2000 rpm but it ranges from 300-1500 when idling after start. Also when I drive home from work it tries to idle as low as it can then if I don’t rev the engine it usually dies in the middle of traffic. Once it’s going it’s fine though. I’ve already cleaned the IAC and the Mass airflow sensor. Maybe one needs to be replaced or just a tune up? Anything will be appreciated. Thanks.

Hey there Tex, I dont see which engine you have in your 4 runner but I am guessing it is one of the V6’s that Toyota makes. When you say “funky idle” do you mean that the idle is “hunting”? Hunting means that the idle is basically surging from low to high rpms and when you arent on the gas may dip low or high in rpms… I am thinking this is the condition you have… If you already cleaned the Mass air sensor thats a good start, however the condition you have is most likely caused by the Air Idle Control Valve…Was that what you mean when you said IAC? Because there is an Intake Air Temp Senor as well Just curious…Anywho…FIND your Air Idle Control valve… Start your truck and UNPLUG the valve…What happens? No change? Big change? Let us know.

Once you have found the valve…OR WAIT rather before you remove the valve I want you to make absolutely CERTAIN that your cooling system is fully topped off with coolant…WITH NO AIR BUBBLES IN THE SYSTEM…This is enormously important to the functionality of the AIC valve operation…if you have an air bubble the AIC has no chance to do its job properly. ONce you have made sure there are no air bubbles in the system you can go further diagnosing if you need to. There should be a bleed nipple on your cooling system to “burp” any possible air out of the system. The reason you need to burp the system is to make certain that the AIC valve is always immersed in Coolant…It uses the coolant temp to determine how much of a “controlled Air leak” the valve will permit…More air leaking= higher idle and less = lower idle… the AIC is a controlled air leak device if you will…it is how 99% of vehicles on the road today regulate their idle.

ONce the system is bled and topped off properly…what do you get? Is it fixed? If not you can then remove the AIC and try to clean her out…usually gummed up w carbon… Clean it as best you can and reinstall…re-burp your system etc…what do you get? In my first test I aksed you to unplug the AIC…after you have they system burped…do the same test and unplug the sensor…What do you get?

You may find that your AIC has simply worn out or is no longer functioning… Do the above tests and let us know what you get. I am fairly certain that either burping the system…and or cleaning the valve may solve your issue…IF the AIC is any good to begin with.

I would start with sea form see if it helps and if not move on to injector problem.

@Waterboy I’ve already used a full bottle of seafoam spray for the air intake and a can in the gas tank. It’s all already been ran through the system. I also added a video of what the RPM gauge is doing in the mornings.

@Honda Blackbird I will definitely try what you suggested. And yes I meant the Air Idle Control valve. When you say unplug the AIC do you mean remove it from the system or unplug the power to the AIC? From what you said about the AIC I’m pretty sure it is the main problem. I ran a diag checker on the system and it continually comes up with an O2 sensor error and I remember it saying something about the mixture being too rich. I’ve ruled out the O2 sensors near the catalytic converter because the converter was recently ripped from the exhaust by a man who apparently needed the money more than he needed clean air… after that the entire exhaust line with catalytic converter was replaced by my local Toyota house.
Would it be worth flushing my coolant and starting new?

I could swear I responded to this & now it disappeared. I think you just have a basic vacuum leak, although a funky idle air control valve can behave similarly. Knowing exactly what diagnostic code you have stored would be helpful. (E.g. “P1234”).

OK the Seafoam… is what?.. injector cleaner? I think from your post that it is…Seafoam makes other products so I needed to ask. Thats a good thing to do periodically but your symptoms are too severe and pronounced to be an injector issue…YET. Cigroller is, as always…correct, a vacuum leak WILL certainly mess with your idle. Remember what I said about how the AIC valve works? More air = higher idle…so a vacuum leak will make the AIC valves attempts at controlling your idle Null and void…Cant have Vacuum leaks ANYWHERE…so you need to look for those…Always. So get these items sorted and let us know what you get.

YES when I said unplug the AIC I meant electrically. Try to follow these guidelines…check your coolant level…no air bubbles… Listen for Vacuum leaks…fix any… and then proceed with my tests. Methinks you will find the solution using all of our advice. Also YES to flushing the cooling system and re-filling with new after you do all this fiddling with the coolant…If its been in there a while, its the right thing to do…No?

SOMEONE STOLE YOUR CAT?!! We have had a rash of that going on over my way. The purps would go to the train station and attack the vehicles on the lot…so when you commute to work with the train and leave your car behind the A-holes are under your car with a batt operated Sawzall cutting your exhaust to pieces in order to trade in your cat at a SHADY recycler who is offering money to these CRACKHEADS… Its the recyclers that I put the most blame on…they should NEVER offer such high dollars to ANYONE who waltzes in with a freshly cut cat. Its a bad situation… There was a guy in Bridgeport, PA just in the news for this type of behavior… Scumbags. Just think…they trashed your exhaust system…to get between 50-100 bucks…leaving you to spend 500-800-1200? on an entirely new factory exhaust system. INSURANCE cover that sort of thing?