Low idle / sometimes bouncy - hunting - surging idle / clicking with bounce

[Jhelms]

Titled the post this way so it can be searched for WHEN I find the resolution - others can find it too.

My latest gunner purchase, when in drive has a low idle. Usually drops to 450-500. On occasion, the idle will bounce from 450ish to 800ish and back down over and over. During this bounce, I hear a clicking like a relay inside the cab (could be coming from engine bay). Engine will do this until I blip the throttle in which most cases it goes back to a low idle and the clicking stops. Power delivery and MPG are great, only idle is funky on occasion. No codes thrown to note.

I honestly have not had time to troubleshoot this in any way as I just bought this particular gunner but will get started this weekend. To note, this is an 01 with the integrated idle air.

Current suspects or ruled out:
- TB needs thorough cleaning as does whatever parts control the idle air?
- Possible defective relay?
- MAF was cleaned, functioning normally
- Car was dealer maintained but oddly, I cannot find any reference to O2 sensors being replaced. Will install new this weekend just because it has 225ish K miles
- Will be doing plugs and wires just because they are about due
- Checked for vac leaks - no issues there
- No cracks in the intake hoses, but they are stiff and old. Replacing both
- Air filter is pretty bad off. Replacing this weekend
- Fuel filter is new
- Coolant is bled properly, no bubbles or suspected issues


Edit:
Found this post with almost the identicle issue / clicking under passenger side dash area. Looks like his fix was a good cleaning of the IAC just as I was hoping. Will keep you updated. Clicking has me baffled though. Wonder if the IAC is controlled by a servo, and it detects the valve is not opened properly and it keeps clicking a relay trying to make it work.... Just a theory.
http://www.toyota-4runner.org/3rd-gen-t4rs/148229-ever-heard.html

 

[Jhelms]

Resolution has been found :bravo:

Wish I could have taken photos, but was in a big hurry.

- Pulled the TB and of course the intake hose fell apart. It was not cracked previously, but pulled on it a tiny bit and it was done!

- There was just enough buildup all the way around the butterfly that it was sort of sticking. Used carb cleaner and a very small wire pipe cleaner to get it all back to good as new.

- What I cannot find pictures of on the net - and not sure if it is the IAC for this TB, is that there are 6-8 small holes that I almost missed seeing. They are at the top of the TB and they reside just above the butterfly. In fact, the butterfly is made to swing to either side of these holes. So when fully closed, air passes through them and when the butterfly is at rest, they are on the intake side.

These had a lot of carbon buildup and not much could pass through them. There is an access panel to get to these small holes on the very top of the throttle body held down by 4 screws. Take off the cover, clean up the holes and make sure they are clear, and re-install the cover. Holes ended up about 100% larger than they were when I found them as they had so much buildup.

- Side note, I took a carbide bur and made the throttle body D gasket and O gasket




Pics are worth a thousand words, so I apologize for not getting them. But good news is, idle is 100% fixed! Runs like a champ now at idle

 

[cashman]

Thanks for the follow up post [MENTION=123173]Jhelms[/MENTION]. I've had similar, though less dramatic symptoms, which were not cured by cleaning the TB. I did not, however, notice or clean the 6-8 holes you mentioned. I'll take another look this weekend and see if those might be clogged.

 

[Jhelms]

I need to research more on exactly what those holes do and if in fact they are a part of the IAC. It is interesting that they are positioned so the butterfly can move so they are on the intake side or the manifold side. It is also interesting that they built the TB with a top access panel so you can easily get to those holes for cleaning.

 

[ajonesnv]

Im in the middle of a similar hunt. I have pulled the TB and taken the IAC off to clean it out really well, but as my luck would have it, it seems to be a vacuum issue cause by the vapor canister.

So far I have:
Cleaned the MAF
Replaced the whole TB with another...cleaned of course. Replaced IAC gasket
Checked for any vacuum leaks
Resealed the canister and replaced the main VSV
Tested the alternator (someone form another thread thought this could be the problem)

It only, only, only happens after the truck has been in the heat long enough to have pressure build up in the tank, I also have a pending P0446, which also points to the canister. And the other day I had enough build up in my tank that when I pulled the cap it vented for about 30-45 seconds.

My take from his problem, most times it the IAC, based on many searches. But there are few of us with peripheral issues. Here is a Let me google that for you search link I used for the problem...(I mean nothing by the LMGTFY, its just the only site I know of that provides a search link.)

The weather is about to cool down, so Im sure I will see less and less symptoms. I might even wait till spring to bit the bullet on the canister.

Good luck to other searchers...it can be a troublesome issue.

 

[ajonesnv]

- Side note, I took a carbide bur and made the throttle body D gasket and O gasket

This is something I did too, and most likely its unrelated, but thats about when all this started happening. So I bought a new TB gasket to get it back to stock, just in case. It shouldn't be a contributor to the issue, but going backwards helps me isolate the problem

 

[Jhelms]

Just to note, the 01-02 TB and IAC is vastly different than the 96-00