22-re cold idle low, warm idle high
 

Been fiddling with the engine a little here and there, and getting no where. I am going to pull the throttle body this weekend and adjust the TPS, and clean the IAC. The RPMs will go up and down around 100 rpms when the truck is idling, or I am just off the throttle. I know the main cause of this is likely to be the TPS, but I have not had the time after work to adjust it properly.

The thing that has me scratching my head, is the idle on start up is very low. It stumbles between 350-550 rpms right now. Once it warms up, the truck idles around 1100-1400 rpms. I checked the plug to the cold start injector, and its on the correct way. Could this be from a faulty cold start injector?

Come on guys. I want to follow this one for my truck too.

Reading up more in idle problems, it really sounds like the IAC needs to be cleaned, and possibly adjusted as well. Its raining outside though, and doesn't look like it is going to let up any time today. I'll post the results once I get a chance to work on it :)

Last night on the way home I had to fill the 4runner up with gas. I put mid-grade instead of regular to see if it would make a difference. Just took it to get some lunch, and the RPMs are much smoother now, throughout the RPM range.

Now I just need to clean the IAC, and get the idle in the proper range.

clean that and check your spark plugs.

New plugs and wires, as of last weekend. Also replaced the HG and intake gaskets last weekend.

The previous owner told me that the block was decked and bored, so it has a higher compression now. The pistons were stamped .050, I assume that means it was bored 0.50" over. So with the work done to the engine, I am starting to think I need to run a higher octane fuel in it, or maybe I just need to change the gap on the plugs?

I mean you read your plugs to see what is going on. I doubt the decking and over bore raised the comp ratio enough to need high octane gas. You would hear a pinging sound running 87 if it needed the 93 and up stuff.

Might not hurt to double check that the coolant line that goes out the side of the IAC isn't clogged. I had the same idle issues on my truck for a long time. While I had the IAC off i noticed that the coolant line leaving the side had some crap in it. So i cleaned it out and now it idles like normal. It makes the truck much more enjoyable to drive. Anyways just something to check out.

I still haven't had the time to remove the IAC and clean everything yet. But I am really suspecting that it is the IAC causing the problems. I'll make sure I clean the coolant lines for it as well :)

Cleaned out the IAC, throttle body, and adjusted the TPS. Idles better now, though the throttle still sticks around 1100 rpms at times due to a weak throttle return spring from the dash pot. The spring was missing completely when I got the truck, and I found a spring that worked in place of it. Over time it has stretched, and lost its strength so I had to clip a few coils. The dealership couldn't find the part, I need to find the part number so I can fix it with the proper spring.

Well it seems I am chasing the idle problems around in a circle. I have the throttle return spring working great now, and once its warmed up it drops down to 750-900 rpms.

But also once its warmed up, if I turn the engine off for 10 minutes, or even a hour the idle at start up is very low. It will idle around 200-400 rpms, once I drive it half a block or so it is back to the normal range.

For a week or so I tried running it with the timing retarded around 10 degrees with the jumper in place. It idled much better with the timing retarded, though I felt 10 degrees was a bit extreme. It runs great either way, and I felt maybe with the higher compression I would need to retard the timing slightly to get a later spark.

So should I retard the timing back again? Or is there a better solution to my issue? I've adjusted the TPS and cleaned the throttle body out. The plugs and wires are new, though I should pull a plug and see how it looks.