IAC Question - Toyota Nation Forum : Toyota Car and Truck Forums

mspringer · 11-27-2010, 12:27 AM

Hi,
I recently (spent the big bucks &) replaced the IAC, and the new one only worked for a day or so. (Not an OEM part, but I'm not knocking aftermarket.)
Using a Scangauge, the idle has always been 750 or so, in gear. Recently its been at 650 or so.
After replacing the IAC, the idle was perfect (back at 750) for the evening. By the next day, same problem...
I ordered another IAC, thinking this one may be defective. The local parts store is cool, they will refund the 1st.
Anyway, my question is with the lines that attach. I thought both were coolant, so I stupidly didn't bother labeling them, and after removing them, I think one is a vacuum line, and I just want to make sure that I put them back correctly. (I think I did, I just want to double check.)

From the fender, looking at the throttle body, the coolant line is on the left (towards the front of the car) and the vacuum line is on the right (closest to the firewall). Is this correct?

Thanks for the help.

***LynchburgCSI*** · 11-27-2010, 01:22 AM

100rpms? Honestly, I think that's within spec.

mspringer · 11-27-2010, 01:36 AM

Well, there is a noticeable increase in vibration at the lower rpm, which disappears if you raise the rpm with the throttle a little (its an automatic), or shift to neutral.

Also, I replaced the torque mount, motor mounts, and transmission mount last month. Only the torque mount appeared to be bad.

I cleaned the throttle body before replacing the IAC.

I have a set of plugs (NGK G-Force - or something like that, the mid priced plugs) to put in it, incase that might be a contributing factor. The old plugs are only a couple of years old (same swith the wires). Car has about 150k miles, and it is the mighty 4cyl...

***LynchburgCSI*** · 11-27-2010, 01:45 AM

Let me guess... 3rd generation camry, right? Did you upgrade the dog bone to the 4th gen one? Does it only vibrate in drive?

mspringer · 11-27-2010, 02:11 AM

Sorry, I should have mentioned. Its a 98 (4th gen).

Pvt-Public · 11-27-2010, 06:20 AM

Quote:

From the fender, looking at the throttle body, the coolant line is on the left (towards the front of the car) and the vacuum line is on the right (closest to the firewall). Is this correct?

I believe they both should be coolant. On my 1999 I see no vacuum to the IAC it is electrically controlled.

***Mister_Perkins*** · 11-27-2010, 06:32 AM

yeah those are coolant lines

ajkalian · 11-27-2010, 08:06 AM

If your IACV looks like this, then the coolant lines are the ones on the outside, and the vacuum is the center one. This is a Calif IACV so if you have a Federal one, it might be different. This is from a 2001 Camry LE 6cyl.

.

Pvt-Public · 11-27-2010, 08:20 AM

Quote:

This is from a 2001 Camry LE.

As far as I know 97-2001 4cyl. (Fed. Emis)did not have a vacuum connection on the IAC. The Cali 4 cyl and all the 6cyl. did. If this is wrong please let me know.

carsrus · 11-27-2010, 08:26 AM

The gen 4 shakes a bit during idle. Its normal.

650 idle rpm is pretty typical. Remember that when it gets colder out side no A/C running will drop the idle down a bit.

peshwa · 11-27-2010, 12:08 PM

Ideal 'Idle' is 750 rpms when in Park/Gear
Around 1000 rpms when in Neutral
There should be a slight jump in rpms while changing between gears.
The IAC themselves will not go bad. There is the electronic connector on the IAC that could go out of spec. Replacing that part from car salvage yard should be very cheap and an easy first step.
Throwing money at replacing parts wouldnt help you much IMHO unless you hunt down the root cause.

Pvt-Public · 11-27-2010, 03:33 PM

Quote:

Ideal 'Idle' is 750 rpms when in Park/Gear
Around 1000 rpms when in Neutral

And I always thought the IAC's job was to keep the RPM at 750 +/- 50 regardless of whether it was in gear or in park/neutral or even if the AC was on. Mine idle stays the same in drive, neutral with or with out the AC on.

mspringer · 11-27-2010, 10:43 PM

Quote:

Originally Posted by Pvt-Public

I believe they both should be coolant. On my 1999 I see no vacuum to the IAC it is electrically controlled.

Thanks for the replies, all.
I was not sure if they were both coolant, or not. One was full of coolant, and the other did not seem to be, or at least it wasn't spilling out...

Also, I have an IAC with two hose connections (Fed) not the California model.

I have not had a chance to look at it, but something minor seems to be wrong. I have put 90k on the car, over the past 5 years or so (I bought it in 2005 with 58k ... for $2500-don't hate!) and it is usually much smoother.

I am still thinking its the IAC, as it does idle up when the compressor kicks on. I'll check more carefully for a vacuum line that I might have inadvertantly knocked off, or something, and I will put a set of plugs in it.

I was also thinking I would go back and check the bolts on the new motor mounts, and make sure nothing loosened up there, as well.

***fenixus*** · 11-28-2010, 04:36 PM

Quote:

Originally Posted by Pvt-Public

As far as I know 97-2001 4cyl. (Fed. Emis)did not have a vacuum connection on the IAC. The Cali 4 cyl and all the 6cyl. did. If this is wrong please let me know.

calif emission specced camry/solara had Air Assist (3rd tube for vacuum) only until 1999. since 2000 even calif specs models do NOT have the 3rd IAC port (no more air assist).

***fenixus*** · 11-28-2010, 04:40 PM

also 4th gen camry (4cylinder) engine idle speed (in Neutral gear with all accessories OFF) are within specs as 700+/-50 rpm.
engine speed in driving gears is more or less controlled by computer, but things like Throttle plate adjustment screw and vacuum leaks will obviously affect it to some point (ECU will try compensating).