Stuck High Idle

Well it’s not the plugs or wires.

I’m going to proceed to changing the IAC gasket I definitely have a leak in that area. See video below.

https://youtu.be/F7c3Bc3OclQ

what I don’t get is I had a lean condition before the IAC; maybe I made it worse when I changed the IAC but not the gasket.

 

Hey sorry for the late response, I just saw this one. It must have snuck by.

Its definitely something difficult to do, especially if you have big hands. You just have to get around in there from the exhaust side and get the sensor connector off. I just did it while installing the new throttle body to test the IAC.

After that I just use a small 1/4 socket that you can adjust the angle on, so it fits in really small area. You pretty much just have to do it by feel. Its a pain in the ass especially if you have to get an old gasket off...

Ive only ever done it with the valve cover off though, most ive done is replacing the connector wit the valve cover on, not actually replacing the ECT sensor.

Good luck

 

Just put on the new TB from Maxbore. Initially started it up and it went up to 2,000 RPM. Gonna let her computer figure it out over the next couple days and see what happens.

The TB's that I got back from him look really nice, essentially like new. Id say work defintely well done and worth the $150 bones.

Fingers crossed! I dont drive a ton, so ill update in a few days and hopefully the idle will start to settle out.

 

new iac gasket making on top of that didn’t fix my issue; the test in the video still has the same results. Think I’m going to pull the throttle body assembly and iac and seal every potential for a leak with gasket maker. I’m tempted to put my old iac on too...

 

Have you ruled out your intake gaskets or possibly a cracked intake manifold? I wonder if there might be something on your intake?

I guess its good to start with the throttle body because thats easy to seal up, but next that might be a possibility

 

I’m thinking that when I tried to shove that throttle body spacer in there that something came loose or cracked. It ran absolutely terrible with that spacer in there so I took it out but kept the cold air intake. Then the lean error codes started followed by misfires.

back to what you said about the intake it sure is hard to see on the underside of the intake. I shot all the intake gaskets with the carb cleaner and got nothing. That iac/throttle body area keeps showing an rpm increase. I was certain it was the iac gasket but apparently not. This corona business has me working 7 days a week now so who knows when I’ll be able to get back to it..

 

I forgot to mention that I have sprayed high and low and that is the only spot that creates a rev of the engine.

 

i was just gona say to check this, iam starting to have wierd idle now and this ni came across on my truck too, i too have a pretty big ga, ALSO cheal the tube that goes to the pvc valve, and MORE IMPORTANTLY clean the part of the intake manifold, i had 2 use a lil flexible brush 2 get ALL the gunk out, it was tottaly cloged. il see if i can find a pic...but also m check that my truck has 239k 2rz.

 

Holy crap your video of the weird noise after you turn it off is the weird loud ass noise I get just like that but only in warmer weather and freeway speeds. And it's loud when it 'pops' or 'clicks' I don't know which word describes it best.... I could never figure out what it was until just now. And it's done the noise since I've owned it, like 3-4 years. Makes me happy man. Thank you so much for posting the video

 

Well it’s embarrassing to say but I think it was that I had the throttle body gasket turned the wrong way and it was leaking like a sieve along the bottom. Here is a before and after video.

https://youtu.be/uQE_uxbSdw4

https://youtu.be/VHTVY_-breo

After that it was starting really rough; I think I got that mostly ironed out. The set screw on the throttle That sets the minimum position of the throttle when the truck is off had been adjusted all the way in by me assuming I was leaking too much by the throttle plate. As soon as vacuum is pulled the diaphragm pulls the plunger away from the set screw allowing the idle air set screw to come into play. I actually had that one adjusted too far open causing idle around 1,000 rpm.

I had replaced the idle wire control valve hose with generic hose and it is kinked which is requiring me to set the starting set screw further open than stock. Does anybody know where you can buy one? The yota shop was checking for me as they only had 1999 and up hoses.

 

i love repairs like these!!!

we get sooooo into it, and dont even pay attention to the basix, iam in the hvac trade and i DO THIS ALOT lol, glad u got it all figured out.

 

Awesome, glad to hear its running good!

 

Ok time to report back!

I got the throttle body on there and initially the idle was around 2,000 RPM. At first I figured the ECU would figure it out, so I didnt reset it, but then after a week of driving and no change I decided to unhook the battery and let it sit overnight. I had a trip to do the next day and success! After about 250 miles of driving the idle is for the most part back to normal. And the start issue is fixed as well. Ag this point ive put just under 600 miles on it with no check engine light!!! Prior to this and resetting the ECU I had the following intermittent codes:

P0115 (Saw this after testing the IAC and I think it was just a temporary poor connection, but this one had me worried for a minute)
P0420 (Pretty consistent)
P0300 (only occasional and would come and go on its own)
P0505 (On occasion)

The idle is not 100% back to normal and I think the issue is still the idle controller. I had several idle controllers in my garage and two sources for test information on them:

1. The FSM has you test it by plugging the IAC in and unhooking the ECT sensor plug.

Using this test, I was not able to get any of the idle controllers to test correctly. One of them was brand new and two of them have less than 500 miles of them. So the chances of them all being bad are low. Not sure why they would not test correctly, as now the idle seems to be fixed and the IAC is working.​

2. The Haynes manual has to test resistance between two of the terminals.

Using this test I got wildly variable results. This calls for an Ohm reading of 18-25 if I recall (dont quote me on that). The brand new one I got tested around 8-10 ohms. And the only one that fell within the range is the one that I used.
​

So I ended up putting a used IAC on the refurbed throttle body and the idle sometimes still hangs out around 1,000 RPM. This is sometimes fixed by revving the engine, but sometimes it will not get the idle to go lower. The only way the idle will go lower is when you rev the engine up above about 2200 RPM, then it SOMETIMES settles back down.

Sometimes I dont even have to do anything and it idles correctly down at 600-750 RPM

So my thought is that, even though I cleaned the IAC it might still be a little sticky. Those things are difficult to clean, and I didnt lubricate it, which id imagine is something it needs. I have a bunch of these little IAC's in my garage at this point and was going to take them apart, but they have a weird screw on them. it looks like a Torx bit, but instead of a 6 point star, it is a 5 point star. And I cant find the bit for it anywhere in town. Anybody know anything about taking these things apart and cleaning / lubricating them that way? Even using carb cleaner and a q-tip there are still a lot of nook and crannys in there that dont get 100% clean.

Another idea I had was to just take the intake partially off and put a couple drop of marvel mystery oil in there and see if it helps with getting some lubrication so that I dont have to tale it off. Thats going to be my first step and then go from there so I dont have to take the TB off again.

For the record im really happy to have a normal running truck with no check engine light!! Wahoo, its been a long road...

 

I read you report. Remind me what all you have checked. I’m having rough starts that I think are due to a flimsy iac hose replacement . I’m going to put a factory one on in the morning and see if that was it. Truck has always started strong so I’m perplexed. It even started strong with the major vacuum leak.

 

My idle is about 1,000 rpm in park and about 750 in drive. See attached video does anybody else’s vapor canister making this whooshing noise.

https://youtu.be/48BqIWLuYjc

 

Sorry for the slow replys, im really busy and ways forget to check this...

Replacing the head gasket was the first major job I did on this truck. While I was doing the head I some how severed a wire to the Engine Coolant Temp Sensor, which is on the back of the block. The result made for difficult starting when cold. I just had to replace the connector there, which was really the only time I had a starting issue. (very difficult to start when temp below freezing)

Then I had a sticky IAC and cleaned the throttle body which led to this thread. So after having the initial issue I replaced the IAC, replaced the throttle body with a used TB I got on ebay. This one had slightly less wear, but still resulted in an idle RPM of about 1,000. At this point i didnt replace anything, but did inspected and cleaned the EGR (There was nothing wrong with it) and took it into a mechanic shop where they found the following:

1. P0420 - This one has been there since the throttle body issue started
2. P0300, P0301 and P0304 - These have been intermittent and all indicate a misfire of some sort
   • They checked compressions, which were all between 165-170 PSI
3. They found a vacuum leak, which turned out to be the PCV. So the PCV was replaced to correct the leak, but this resulted in no change to the idle. Not sure if it was a faulty valve or what, but it wasn't drawing a code (dont think there is one).
4. They also said disconnecting the IAC resulted in a slow steady idle and thought the IAC was the problem

So I didn't really replace a whole lot for parts. I also did the normal checking of O2 sensors (which both tested the same as a new O2 sensor) and tested the MAF sensor which tested fine.

Essentially I kept coming back to the throttle body, which turned out to the solution. Right now the truck idles good, its still learning how to idle and is slow to go down to 750 RPM after warming up, but does it just fine.

Did you get your TB done by maxbore? I think you should start there if you have an old TB. The one that was on my truck that was causing the 1,000 RPM idle really wasn't very worn, but it was worn just enough to cause the issue. I just looked at the pic of your TB again and the one I had on my truck prior to the fix was less worn than that....

 

I did not send mine off; my biggest issue was the throttle body gasket being upside down. Now I am trying to figure out why my charcoal canister evap silenoid valve is opening and closing and looks to only be getting 6 volts... started another thread but no advice.

 

That going to be a difficult problem to chase. The TB would be a cheap fix (less than $200) and would likely fix your idle if thats what you're going for.

If I could have done it all over I would have replaced that TB first rather than buying a used one. It makes sense that its what causes the high idle. More air getting past the throttle plate means more vacuum, more fuel, etc...

I think its probably easy to over think and chase problems that you think are causing it. But the reason im saying this is because i was way over thinking mine, thinking it was related to the ECT and the ECM may be causing issues, when it was just the TB. And my TB had less of a gap then yours does in the pic you submitted