High idle? Stumped.

[Ask10]

Hi all,

So, high idle, 3.4 Limited 4x4. In neutral it idles at 1700 rpms regardless of engine temp.

I just changed the timing belt and a whole lot of other things, but the only thing I can see relevant to the idle itself is that I cleaned the throttle body out. The moment after I started the truck it idled fine, 800 rpms ish. Then the moment I tapped the throttle it "rocketed" up to 1700 and has not come down since. I have tried to....

Adjust the throttle cable
Tried shimming the throttle linkage via the "High idle CURED" thread
Adjusted the vacuum switch on the side of the throttle body
Tried cleaning the IACV, but didn't take it off the TB. I just sprayed cleaner on it with the TB off the manifold.
and checked all the connections, leaks etc.

Found nothing. If I physically try and turn the throttle "down" by hand, the idle remains the same, 1700 rpm, meaning it's not a physical hang up, something else is causing the truck to idle up.

Anyway, wondering where I should turn next and if anyone has had a similar issue.

Thanks!

 

[IBallEngineer]

Hi all,

So, high idle, 3.4 Limited 4x4. In neutral it idles at 1700 rpms regardless of engine temp.

I just changed the timing belt and a whole lot of other things, but the only thing I can see relevant to the idle itself is that I cleaned the throttle body out. The moment after I started the truck it idled fine, 800 rpms ish. Then the moment I tapped the throttle it "rocketed" up to 1700 and has not come down since. I have tried to....

Adjust the throttle cable
Tried shimming the throttle linkage via the "High idle CURED" thread
Adjusted the vacuum switch on the side of the throttle body
Tried cleaning the IACV, but didn't take it off the TB. I just sprayed cleaner on it with the TB off the manifold.
and checked all the connections, leaks etc.

Found nothing. If I physically try and turn the throttle "down" by hand, the idle remains the same, 1700 rpm, meaning it's not a physical hang up, something else is causing the truck to idle up.

Anyway, wondering where I should turn next and if anyone has had a similar issue.

Thanks!

First thing I'd be looking at is the throttle body AGAIN. If you can see the butterfly, make sure it is closing correctly.

Next thing I'd be looking for is a vacuum leak. Anywhere! The IACV is nothing but a computer controlled vacuum leak. Add air, computer adds fuel, hence the higher engine speed. And don't rule out the IACV itself, so maybe remove it and make sure it isn't hanging up on something that broke free when you sprayed it.

Never had this happen on a Toyota, but I've seen similar issues on Fords and GM products.

 

[Izlu]

Computer adjusts idle so it needs some time to readjust it after throttle body is cleaned. Drive for few hours and see what happens, idle should go back to normal gradually.

 

[sggaz]

Computer adjusts idle so it needs some time to readjust it after throttle body is cleaned. Drive for few hours and see what happens, idle should go back to normal gradually.

I believe that disconnect/reconnect of the battery will cause the computer to reset/recalibrate based on current readings rather than adjusting down over time. I'm not sure if the battery needs to be disconnected for a certain time period for this to happen.

 

[jonnieguns]

I believe that disconnect/reconnect of the battery will cause the computer to reset/recalibrate based on current readings rather than adjusting down over time. I'm not sure if the battery needs to be disconnected for a certain time period for this to happen.

Reset the EFI relay by removing the fuse in the driver's side fuse block in the engine bay (keep the battery connected). Let it sit for about half an hour, reinstall, and then try it out.

 

[Ask10]

Thanks for the replies so far.

I opened up the intake to see the TB and made sure it was closing. It was just fine and there was no more room left to close, not even a tiny amount.

I've since put 60 miles on the truck and it's consistently 1700 rpm idling still. Blipping the throttle does nothing, but I did find out that when it's cold, it's somewhat hard to start now. Also when cold I get a slight misfire, not sure if that has anything to do with it.

I'll dig into the IACV and go from there I think.

 

[kingin]

Reset the ecu? I just did valve cover gasket cleaned intake etc had high idle after unplugged positive from battery terminal for 10mins. Idles perfect now

 

[kingin]

I take back the reset ecu lol my idle is stuck at 1100 still.

 

[0xfded]

FWIW, my '98 had this exact issue (~1700 idle at any temp, throttle looked fine, no vacuum leaks), and it ended up being a bum IAC.

$70 replacement, 30 mins to swap, and it completely settled things.

 

[Ask10]

I tried to clean out the IACV on the first post of the second page of this thread to no avail.

http://www.toyota-4runner.org/3rd-gen-t4rs/109418-high-idle-when-warmed-up-2.html

1700 rpm idle... I removed the TB again and cleaned it out the best I could with a whole can of carb cleaner, some q-tips, etc but nothing.

I guess I'll just have to order a new one and go from there.

Thanks again all

EDIT: Sorry for asking, but where were these "magic" $70 IACs? Rockauto said they had none and were $133? I don't mind paying that much as it's been a good truck, but if it's cheaper of course you know...

 

[TXRick]

I had constant 1700 idle for a while. Cleaning the IACV isn't enough to tell if it's busted. Remove it and check it. You have to supply power to the pins and see if the valve opens and closes. I think the middle is ground.
I also inspected the butterfly blade to make sure there were no gaps. Mine was a little gappy so I adjusted the two stops on either side. You might want to try that. My idle is pretty much fixed but I think I still need to replace my IAC because when I tested it, it moved more when I charged the right pin than the left. I'm at 700 most of the time but it might get to 900-1000 rarely. I'll look for my post with pictures.

Here it is...

http://www.toyota-4runner.org/3rd-gen-t4rs/166432-high-idle-throttle-body-question.html

 

[knightrider]

I had the same issue recently, I took my iacv off and actually took the motor off the valve and cleaned the he'll out of it w tb cleaner and moved the valve stem back and forth while soaking, the valve should move freely once properly cleaned. I then made sure the passage way for the iacv was thoroughly cleaned too while the tb and iacv body was off. Got back together and once the motor was at running temp it settled back to 550-600 rpm. Hadn't had an issue yet.

 

[0xfded]

EDIT: Sorry for asking, but where were these "magic" $70 IACs? Rockauto said they had none and were $133? I don't mind paying that much as it's been a good truck, but if it's cheaper of course you know...

I nabbed mine on ebay around a year ago. Here's a listing for $75.

It is ebay, though, so caveat emptor. Worked out fine for me though.

 

[Ask10]

I had constant 1700 idle for a while. Cleaning the IACV isn't enough to tell if it's busted. Remove it and check it. You have to supply power to the pins and see if the valve opens and closes. I think the middle is ground.
I also inspected the butterfly blade to make sure there were no gaps. Mine was a little gappy so I adjusted the two stops on either side. You might want to try that. My idle is pretty much fixed but I think I still need to replace my IAC because when I tested it, it moved more when I charged the right pin than the left. I'm at 700 most of the time but it might get to 900-1000 rarely. I'll look for my post with pictures.

Here it is...

http://www.toyota-4runner.org/3rd-gen-t4rs/166432-high-idle-throttle-body-question.html

I had actually read your thread and checked the butterfly, but it was perfectly centered and there was no slop on either side. Odd, this truck has 277k on it.

Either or, thanks again all for the info and thanks for the links too. Everything seems to point to the IACV, so I'll just assume it managed to go bad in the time it was sitting off to the side while I replaced the timing belt. Almost a relief, I thought I did something wrong. lol

 

[SilverRidgeRunner1]

I can't recall the procedure, but if I'm not mistaken isn't there a idle relearn procedure that could be preformed to correct the issue. I recall Toyota having a procedure on certain models Camry, Rav4, tacoma, and I believe Land Cruiser and 4-Runner. Also could the timing have gotten advanced/retarded by a little causing the computer to compensate when doing the timing belt.

 

[Ask10]

Well, I replaced the IACV and....it's worse. It idles at 2000 rpms now. So much for that, I even spent "big money" on a genuine Denso one from Toyota.

I rechecked all the vacuum connections and they were good and tight, I made sure the butterfly was closing, I checked that the new valve would rotate freely etc (the old one did too), but now...I'm out of ideas.

 

[JRZEE2000TR4LTD]

What is your manifold vacuum at idle?

 

[Ask10]

^^Not sure, don't have a vacuum gauge BUT, solved!!!

I was looking at the old valve and saw that while the "butterfly" valve was moving freely for the most part, it seemed to be hanging up right before it closed. So I disassembled the whole thing and cleaned it up and got it to the point where it moved from open to close with no hang ups at all. Didn't think it would make a big difference.

I was right, it didn't, but then I forgot that maybe the ECU needed to learn something new so I undid the battery cable and waited. After a while I put it back on, took it for a short drive around and it's now hovering around 700 rpm in DRIVE with the A/C on! Hopefully it stays that way because I'm returning the new one I just got, lol.

So, solved maybe, but for now I'm calling it good.

So keep that in mind anyone in the future, the ECU might need to relearn how to idle since the old valve wasn't working beforehand.

 

[Ask10]

:frusty:

Idle is now erratic between 400 rpm and 1300 rpm, absolutely no bearing on the temp of the motor. 400 rpm was stone cold and then blipping the throttle took it to 1000. Then the A/C kicked on and 600. Then after it warmed up, 1300. As of now just coming home, sitting in the garage it's hovering at 1100 in Park. :shrug:

I think the old valve was bad, I somewhat "saved" it, and now it's acting up again. Maybe I wont return the new one.

 

[jgue467]

:frusty:

Idle is now erratic between 400 rpm and 1300 rpm, absolutely no bearing on the temp of the motor. 400 rpm was stone cold and then blipping the throttle took it to 1000. Then the A/C kicked on and 600. Then after it warmed up, 1300. As of now just coming home, sitting in the garage it's hovering at 1100 in Park. :shrug:

I think the old valve was bad, I somewhat "saved" it, and now it's acting up again. Maybe I wont return the new one.

FSM says for high idle to check: 1) A/C signal circuit (Compressor circuit) and 2. ECM power source circuit.

For hunting (erratic idle) check: 1) ECM power source circuit and 2. Fuel pump control circuit.

Use the FSM's diagnostic procedures and you'll find the cause of this peskly problem. Luck! :banana:

http://www.toyota-4runner.org/3rd-g...faq-tutorials-documentation-reference-v2.html