DOT3

I've got the high idle virus now. It surges most of the time between 1200-1800 and when you push the clutch it will try to go to normal and bounce back up.

1999 v6 sr5 manual trans 170,000 miles

I replaced the IAC (it did not ohm to spec), cleaned the TB, and checked ECT, TPS and they are operating normally. The ECT reading indicates an operating temp of about 190F.

It fails the "Air Assist Hose Disconnect Test" that's in the FSM. To do this test you pull and plug the air assist hose and the rpms should less than 500. Mine stayed at about 800. When this test fails, the manual says to "check for a leak between the air assist hoses, pipe and injectors".

How do you "check for a leak between the air assist hoses, pipe and injectors"? I looked around and did not see anything. What pipe are they talking about?

Any help would be appreciated.

Matt93eg

You are not the only one plagued with high idling issues. My 3.4 has done my patience in with the high idling. I have a thread just down below this, read through it if you haven't already. Might see something there you could check also.

With the weather we have been having here in the southeast I was driving my Tacoma, I have parked the darn thing and resorted to driving my 93 Honda Civic. The Civic is older, has more miles and runs like a darn top. And best of all, it idles at 700 RPM just perfectly.

I love Toyota and my Tacoma but this continued problem has just done me in. I'll let it sit and rot in the driveway is the way I feel at this point. I know one thing, I will NEVER EVER clean a throttle body again. Good luck fixing your high idle, I have had no such luck in fixing mine.

If your IACV did not OHM to spec that could be your problem I would think. I had an IACV on a civic goof up one time and after the engine was warm the idle would bounce from around 900RPM to 1,500RPM. It would bounce back and forth like a surge. Turns out that IACV was stuck and after cleaning it, it fixed that problem.

DOT3

I did replace the IAC valve and nothing changed. I also inspected and cleaned the MAF sensor.

My 4runner has all original oxygen sensors. The only engine repairs have been spark plugs and wires, timing belt and associated parts (twice) and a drivers side injector.

Keith B.

Is the high idle due to a not-completely-closing throttle butterfly, like mine had? Can you push it 'more closed' when at idle and have the idle return to spec? Sometimes the throttle plate and/or pivot wear unevenly and/or won't close all the way. There are adjustment screws for the closing spring pressure and stops at the rear of the TB. I don't see how to adjust it w/o removing the TB. My TB got replaced at the dealer ($$$...it was in my budget at the time)and that fixed my high idle. Only after I had the old one in my hand could I see the adjustment screws.

wyoming9

iTrader: (1)

Either of you getting The P0505 Code??

Another ECM cured my issue.

Do you want to sell your Truck??

DOT3

I'm not getting any codes.

Hooked up to the scan tool.

TPS 9.4% at idle
ECT 201 F
IAT 66F
MAF 1.6 lb/min at idle
RPM 950 when stopped
RPM 1000-2000 surge before stop in neutral

RedRockWarrior

Could be your throttle body. I had the same problem. Its not as bad as you think. Well at least for a 22re it wasn't lol. But anyways if thats whats wrong just clean it with tooth brush. very easy cause it will make your rpm's go crazy and pretty much idle wherever it feels like

DOT3

Disassembled it again the weekend.

Carefully checked the throttle body and it's in very good shape. Very little wear and the butterfly is nicely centered with little light shining through. The linkage shaft is smooth with no play. My dash pot and throttle assist passed all inspections. Checked the AC amplifier connector per the FSM and no problems. ECT,TPS and MAF sensors all read fine on the live data scan.

The truck will idle perfectly when you restart it after it's fully warm. As soon as you hit the trottle, it wont't settle back below 900 rpm. It still surges when coasting down from highway speed.

I'm beginning to think the ECM might be bad.

DOT3

I did not perform the air assist test correctly.

To determine if you have air leaks, pull & plug the air assist hose that runs to the IAC valve. Short the pins on the diagnostic terminal and the truck should stall or idle below 500 rpm. Mine stalled meaning no air leaks.

The next step in the FSM is to test the ECM.

Matt93eg

DOT3,

I would like to try this as well on mine. So I need to pull the hose from the very bottom of the IACV and plug it? What pins exactly do I short? I do not have a scan tool of my own which sucks.

I unfortunately am still plagued by the high idle on my 3.4 as well.

DOT3

The fault procedure is in the "DI278" section of the FSM. The air assist steps are on pg SF36 and the pin numbers are TE1 & E1. It clearly states that if the engine idles over 500, to check for leaks between "the air assist hoses,pipe and injectors".

DOT3

Sent my ECM off for testing and it passed. They tested the idle control circuit and no problems.

DOT3

Still fighting the high idle.

Some interesting information from the scan tool:

I've noticed that the MAF sensor is metering all the air flow to the engine. All the surging and high idle conditions are reflected in the maf sensor output. When the engine surges, the maf sensor floats with the rpms and reads as high as 1.6 lb/min of air. Once the truck stops, the maf will drop to 0.7 lb/min which is about 900 rpm. Occasionally upon hot restart, the truck will idle correctly at 750 and .5 lb/min on the maf.

When driving around town, the truck idles almost normally. It does not surge and settles down to about 850-900 rpm when stopped. Coasting off the interstate, it will hang about 1200-1800 or surge in that same range and then 850-900 rpm when stopped.

Any thoughts?

wyoming9

iTrader: (1)

Have you looked at the throttle cable where it comes through the firewall.

Mine broke the bracket holding it to the firewall it caused all sorts of high idle issues without tripping the MIL

DOT3

Wyoming;

Thanks for the idea.

The cable is ok and the TPS always return to 9.4% when I let off the gas. So it's not hanging up on anything. I even unplugged the cruise control to see
if maybe it was going crazy. I got 21 mpg the last tank so the high idle is not hurting me too much.

donomite49

I took the IAC out and adjusted the idle until I have time to sort it out

DOT3

For the last year or so, I worked on and tweeked every part of the idle control system and nothing helped. The old throttle body looked to be in good shape with very little play on the shaft and only a small amount of wear around the butterfly valve. So I finally spent the money and ordered a new TB and it works fine now. The MAF sensor reading dropped for 0.7 to 0.5 # of air flow at idle with the new TB. The TPS reading was unchanged at 9%. The warm idle is around 700 rpm.

Seems like a waste of money since the old TB looks to be in good shape. I guess the shaft play causes the butterfly too wear and let in too much air.

djohn24

Would anyone know if the idle control valves are all the same for the 95 -04 3.4l engines? I bought one off ebay and My son has a 1997
T100. The valve I bought will replace his but on my 2003 4door tacoma, i see nothing under the throttle body matching his idle control valve. Totally different looking. Thanks in advance for any hepl provided!

TheDurk

On 4Runners with the 3.4L, everything changed in 2001 when Toyota made it throttle-by-wire. I don't know when or if they did the same with the Taco, but it's something to look out for. (I just do 4Runners.)

djohn24

Thanks Durk! That would be the case then on my 03 Tacoma. Two wires on the side of the throttle body. Thanks again!!