High idle is really pissing me off!!!

[Dinabox]

So I recently cleaned out my TB and IAC, changed oil and plugs and also new fuel filter. After all this my car idles 1400+ all the time. I know it's supposed to run high on a cold start but after the engine warms up it doesn't drop. There is a spring type thing with a rubber boot on it that if I manually press it down it will idle perfectly, but upon giving it gas it's back to 1400 ish. Also if I rev it to 5k it will drop to normal idle but just regular driving and it never goes to it's regular idle. I've been troubleshooting this damn thing for days know and it's really pissing me off!! I've adjusted the screw and nut on the front of the throttle body with no avail. I purchased a coolant temperature sensor but didn't have time to do that today. I'm hoping it's that or maybe a TPS?? It ran just fine before all of this maintenance. I've pulled the EFI fuse every time I work on it too btw. Any thoughts? I'm really hating my 4R right now and I need to get back to loving her!!

 

[PitbullRescuer]

What year and which engine?

 

[Dinabox]

Crap, forgot to mention that. 96 SR5, 3.4 V6, manual tranny, 4WD

 

[BrianSD_42]

My first thought would be that you have a high mileage V6 and when you cleaned the throttle body it no longer shuts to factory specs. This results in more air getting through and seems like a common problem when people clean the TB.

I have 213k miles on my TB, never cleaned but* I did just order one from a scrapyard. The part came from a 4Runner with 90k. I plan to clean and install it next week.

 

[PitbullRescuer]

Sounds like you messed with a few things so going to be tough to diagnose.
1.) Make sure the UAC is clean and not gummed up from trying to clean it.
2.) Did you mess with the throttle cable at all? If so, make sure it's nit too tight causing it to idle high.
3.) Double check all your vacuum lines.

 

[Dinabox]

Well, I do have a high mileage 4Runner, 217k but I've cleaned the throttle body before and this didn't happen. I never cleaned the IAC before but when I did this time it wasn't that dirty and now it's spotless and all moving parts work, magnet is good, gasket is good and I resealed using some gasket maker. Didn't touch throttle cable so that can't be it, it's always been tight but not too tight. Checked for vacuum leaks as well and nothing. Like I said, if I rev the motor to 5k+ it goes back to normal idle, but just driving around it doesn't.

 

[BrianSD_42]

Well, I do have a high mileage 4Runner, 217k but I've cleaned the throttle body before and this didn't happen.

How many miles ago was that? I only mention that it may be mechanical (just too worn out) because they are a few other threads that imply as much. Pehaps it is the IAC? I just ordered a used one (as mentioned before) because I felt it would work with no problems.

 

[Dinabox]

Had to have been at least 3 years ago. I'm wondering if it's even worth replacing the IAC or TPS or just buy a used TB from a junkyard. I'm at a loss...

 

[BrianSD_42]

Well I will let you know how it goes when I install it next weekend.

My problem is low idle ~ 600rpm with a rumble.

 

[aqspham]

Weird.. I just cleaned out my TB as well. At start up it doesn't rev high like it used to (around 2k + rpm then after a few seconds it would drop back down to normal, around 1k). The weird thing is that after driving, and putting the truck into park or neutral, it revs at 2k+ and doesn't drop. I haven't tried letting it sit for more than 1 minute to see if it would drop but it didn't seem like it was going to either. I did tighten the throttle and transmission cable, I'm going to try to loosen it a little to see if it changes. I know you mentioned you didn't tighten yours, so if it doesn't work for me, then we'll both be in the same boat! :sobbing:

 

[mmml4]

Sounds like the dashpot is sticking, the spring like thing with the rubber boot.

 

[Drcoffee]

I had this happen to me last month. I got my truck to idle again. I ended up pulling off the plastic intake tubing and gave a couple of squirts of MAF cleaner down the hole in front of the throttle plate. I left off the plastic intake tube and started the engine and it fired up and then died. I did that 3 times. What I was hoping is that the cleaner would dissolve the carbon and then suck it past the IAC valve letting it function again and close. I was right. After reconnecting the plastic intake tube it fired up and the idle dropped to 750. I didn't have to remove the IAC either. Don't flood the hole, just two quick shots of MAF cleaner should dissolve any crud.

The reason I used MAF cleaner is it doesn't leave a residue and is less aggressive than carb cleaner.

I hope this proves to be an easier fix for this problem than removing the throttle body.

 

[PitbullRescuer]

Well I will let you know how it goes when I install it next weekend.

My problem is low idle ~ 600rpm with a rumble.

Mine idles right at 600 when it's warmed up. Never thought anything of it. It's smooth and the throttle response is fine. Should it idle higher?

 

[BrianSD_42]

I did tighten the throttle and transmission cable, I'm going to try to loosen it a little to see if it changes. I know you mentioned you didn't tighten yours.

I know a lot of guys tighten their cables and perhaps some do need it but when I did mine 6 mo ago it caused a high idle. A few weeks later when i was at the shop for something else I had them look at the high idle. The shop head (who specializes in Toyota trucks) told me that the cables dont strech and in most cases the pedal is bent. That the computer controls will get screwed up if you tighten the cables too much.

 

[JohnsD90]

mine idles at around 700 or so, 600 can't really be that bad, useless its noticeably starving the motor, but on an auto the idle is generally a little bit higher when in drive to compensate the want to move forward.

 

[Dinabox]

Ok so I went to our local stealership and had them run a diagnostic to check for any codes it was throwing. None at all. Had 3 guys look at it there and they couldn't figure it out either. Did everything I've done, lubed the linkage and springs on the throttle body, they even messed with the little 8mm allen screws with the 8 mm nuts on them. I've done that too seeing if it did anything and I'm still in the same boat, high freaking idle!!! I found a thread on yotatech where a guy replaced his TB gasket and it solved it for him, my gasket looked fine but after I go snowboarding today I'm going to replace that and see what happens. So my question is this: even though I didn't throw any codes, could it still be the TPS or IAC? In that same yotatech thread they said if you thoroughly clean the TB without taking the TPS off you could damage it, which I didn't disconnect while cleaning. It's either that or buy a used TB from a junkyard at this point, so frustrating!!

 

[Dinabox]

Ok so today I installed a new TPS and a new ECT hoping to get rid of this high idle problem. I also cleaned my MAF sensor while I had it apart. Still have a high idle problem and now my check engine light is on. Got it checked at autozone and there are 2 codes, forget them but they are MAF and ECT. Awesome!!! It's so freaking lame, if the engine is warm and I cold start it, perfect idle. The second I give it any gas or start driving, 1200-1500 idle. I rev it to 4-5k, drops down to perfect idle again. Pulled negative battery terminal and efi fuse and efi relay while I was working on her. I don't know where to go next. Used throttle body from a junkyard?

 

[EmptyZ]

You have a small propane bottle? If you do try spraying the propane around the gaskets on the intake. If you hear a bump in the rpm then you found a leak in the gasket, replace it. I do know you can damage an IAC pretty easily, I doubt you damaged the tb. You could pull an IAC off a scraped car and try it.

The only other thing I can think of is resetting the pcm, maybe the comp needs to relearn for the higher air flow. It takes more than a few seconds with out power for the pcm to wipe out. They have lots of caps to keep em going.

Below is what the FSM states for Idle inspection:

IDLE SPEED
INSPECTION
1. INITIAL CONDITIONS
(a) Engine at normal operation temperature
(b) Air cleaner installed
(c) All pipes and hoses of air induction system connected
(d) All accessories switched OFF
(e) All vacuum lines properly connected
(f) SFI system wiring connectors fully plugged
(g) Ignition timing checked correctly
(h) Transmission in neutral position
(i) A/C switch is OFF
2. CONNECT TOYOTA HAND-HELD TESTER OR OBDII SCAN TOOL (See page EM-9 )
3. INSPECT IDLE SPEED
(a) Race the engine speed at 1,000 rpm for approx. 5 seconds.
(b) Check the idle speed.
Idle speed: 700 ± 50 rpm
If the idle speed is not as specified, check the IAC valve and air intake system.
4. DISCONNECT TOYOTA HAND-HELD TESTER OR OBDII SCAN TOOL

Also I know you aren't throwing any codes but under p0505 which is for idle speed malfunctions it states that the trouble areas are the air induction system, the electronic throttle controls, and your pcv valve and hose. The problem has to be in those areas.

 

[BrianSD_42]

You have a small propane bottle? If you do try spraying the propane around the gaskets on the intake. If you hear a bump in the rpm then you found a leak in the gasket, replace it.

Sounds like a good way to blow yourself up.

 

[TheDurk]

Sounds like a good way to blow yourself up.

A lot of people do it...but I agree with you.

I've always used a fine mist of H2O. Instead of speeding up, engine will slow down and run rough. Works just as well and whole lot safer.