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I’ve had the problem for a long time now, lol. I think almost 2 years, but it seems to come around more during winter when it’s cold. The problem is when the truck starts, the idle goes to about 2k (which it did before the problem), but after a few seconds it slowly rises up to about 23-2400 it immediately drops to 2000, goes back up to 2400 and then the idle starts to slowly drop. So it isn’t truly a fluctuating idle as you would see with a vacuum leak or something. It only does it when the truck is cold. I tried to get a vid of it right now, but of course, it didn’t do it lol. I’ll try again tonight. This is racking my brain, so any help is appreciated.
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Try tapping on the IAC with the handle of a screw driver
to see if the idle changes.If it does replace the IAC. Does
the trucks coolant temp run normal?Heat in the cab?Yessir, it has heat and the ECT works as it should. I hooked a scantool to it earlier and made sure it was around ambient temp. My truck unfortunately doesn’t have an IAC :(. I was looking for it earlier too lol.
I’m not sure about that engine, but Toyota had a problem with the 1.8L intake gaskets when the weather gets cold…might be a similar design where all they are is an o-ring. Maybe look for a gasket leak and see if that comes up with anything.
You must have a drive by wire.Have you tried cleaning out the TB?
have you check the throttle plate is not obstructed open?
I would also check for vacuum leaks.Have you disconnected the
battery for any reason?I’ve checked for vacuum leaks before, but I keep meaning to get underneath the truck so I can spray around the bottom of the IM cuz it curves kinda weird haha, so I’ll be sure to do that john.
And come to think of it college man, this problem started after I did the TB cleaning. Thanks for reminding me! Like I said, this was a while back haha and you refreshed my memory! I’ll check the throttle plate asap. I have not recently disconnected the battery. And yes, it’s drive by wire.
Does the truck ever come down to a normal idle or
does it stay high all the time. If it stays high then
there is a problem.the computer should recognize the
idle being out of range.But if the idle is only high
on cold start and does return to normal when at operating
temp.sounds normal.From what I have read these toyotas all
seem to have the same cold idle.Yeah, it comes back down to normal idle. Here’s a vid! It FINALLY did it lol.
http://www.youtube.com/watch?v=_Hou63I5R2M&feature=youtu.beSo I decided to do the TB cleaning again today and the acceleration feels smoother, but the idle problem is still the same. I looked for vacuum leaks again and sprayed carb cleaner virtually everywhere, but couldn’t find anything.
The only other thing that controls the cold idle
is the coolant sensor.You could check the ohm vs.
temperature of the cts.you could also check the 5volt
signal.as the resistance comes down the voltage should
go up.Try resetting the ECU by unplugging the negative terminal of the battery for a while then plugging it back in. If that doesn’t work, check out the idle air control butterfly underneath the throttle body and see if it is seized up or something.
I will check resistance and voltage. Thanks college man!
I’ve powered the truck down a few times, but didn’t make a difference unfortunately and it’s throttle by wire so it doesn’t have an IAC :(. Thanks for the suggestions though, Pengy!This is an interesting problem and it seems you’ve covered most of the basics. The one thing I would try just for the heck of it is to bleed the cooling system. The idle is controlled by the computer and uses the IAC valve to control the air flow. It gets it’s info form the coolant temp sensor but if there is air in the system then the coolant temp sensor will give false readings that might cause the computer to implement a bad idle.
Keep us posted on what you find.
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