Maybe the IACV is no good?

That sounds like an IACV issue, but is there any pending CEL codes? How about the short term and long term fuel trim (you'll need a ODB scanner for that).

Cold start idle is fine I presume?

 

verify hot and cold resistances per the haynes or replace the coolant temp sensor.
then, put your dmm across the IAC and verify that those resistances are correct at each end of the scale, again per the haynes or fsm and also that there is a smooth increase and decrease of resistance as you push in the pedal and release it. if there are any dropouts, then replace the IAC. note that a cheap analog voltmeter is probably easier to see this but a dmm should work also, especially a graphing dmm.
tony

 

Cold start is always good.....I thought the IACV was involved, so I cleaned it, and the problem returned...........how can I test the IACV?.....or a better question is " How can a non-mechanic check to see if a IAVC is working properly?.....just recently the car had a P0446 code that showed up but the idle problem has been present for at least 3 monthes.........

 

Well, it's not recommended to adjust idle adjustment on the throttle body. Because idle problems on these cars are mostly IAC, which are known to be problematic. There's also the engine coolant temperature sensor, but mostly that affects cold starts. But you can double check the resistance of the ECT sensor (2-wire one).

Would stepping on the accelerator still help solve the problem? If so I'd still think IAC needs more cleaning. You might have to remove the thermostat plate so the rotor can spin 360 degrees, and you might want to use q-tips to help clean out the rotor vane and bore on the inside as well (requires removal). So I'm not sure how mechanically inclined you are. You do need a gasket from Autozone or your local dealer and some hose clamps for the coolant hoses so they don't leak coolant while you remove the IAC. Clearly do this when the engine is cold. You don't have to remove the throttle body, but it'll be much more difficult and easy to strip the screws if you don't.

Besides the resistance check of the magnetic motor, which I don't think goes bad often at all, you can cover the inlet after removing the air duct and see if the engine runs rough or stall. You can disconnect the connector to the motor and see if the idle speed fluctuates (not a reliable test). Or, remove the motor and turn it by hand, see if idle returns to normal as YOU open up the rotor. Be careful of hot and moving engine parts, plus other precautions when working around cars like applying parking brakes, chock the wheels, etc.

http://www.dummies.com/home-garden/car-repair/auto-repair-safety-rules/

 

yes, stepping on the accelerator helps the problem but I need to move foot from accelerator to brake pedal to shift it into drive......this can be difficult as the car wants to stall................

 

today I realized that behind the butterfly valve are the two connecting ports......so I sprayed both of these openings with TB cleaner and got alot of brown junk and sand like particles free. I sprayed all three of the air ports until the fluid draining out of the middle tube from under the IACV was clear- hopefully this will be enough to clean it properly without having to remove it. Any suggestions on how I should lower my idle back to where it should be?

 

Pull the intake hose off the throttle body when the engine's running, with the car warmed to operating temperature. Cover the port (TB bypass for IAC) you see inside the TB with your finger. If the idle smooths out to where it should be (750 +- 50 RPM), then you got yourself a malfunctioning/sticking IAC valve.

In that case, I'd take it apart and thoroughly clean it (again?), or grab another from the Pick-n-pull. When reassembling, replace the JIS screws that seize easily with hex cap (Allen) screws + split-lock washers.

 

Will it run without input from the MAF sensor? Or get a JIS screwdriver.

 

^ +1

 

I had the exact same issue and it was the iacv, I took it completely apart and greased the the bearings inside and the shaft and the problem went away. Depending on what kind of valve you have just cleaning the outside parts may not be enough and sometimes you might even have to get a new one

 

yesterday after I got done spraying TB cleaner in the two holes behind the butterfly plate? I tried to start the car without the air intake? attached to the throttle body and the car would not start.

 

Art was right, it needs the MAF. The IAC hole isn't behind the butterfly plate, it's in front of it. Warm up the car, then turn it off and cover that hole with masking tape or something. Reconnect the hose, and see if the idle stabilized.

 

+1 on JIS...won't touch my toys 'phillips head screws' without my #2 anymore...
tony

 

I am just trying to learn here...... don't the two holes behind the butterfly plate connect to the port in front of the plate. From looking at pictures on this site it looks like they all connect to the "open area". At least that was my logic yesterday when I noticed the two port holes behind the plate. Originally I just flushed out the port in front of the plate, but yesterday I sprayed all of them until the TB cleaner came out clean (initially the fluid coming out was brown and full of sand like grit).

 

Well, the port in front of the plate is the IAC inlet, and behind the plate I think is the IAC outlet. If you cover the inlet, you're taking the IAC out of the equation

 

ISB's correct. the IAC provides an alternate path for air when the butterfly is closed, so those 2 holes are how the air comes in and then goes out to the throttle body, allowing the IAC valve to meter the air as a choke would do on a carb car.
tony

 

I sprayed TB cleaner into the IAC inlet in front of the butterfly plate, and using a long straw, sprayed TB cleaner into the 2 IAC outlet ports behind the butterfly plate until the fluid drained clear. It appears from reading this forum, that the proper way to clean the IACV is to remove it. That scares me but will try this weekend. Is there a certain size JIS screwdriver I need to loosen the screws? I also rented a OBD scanner and my LT fuel trims were 1.6 and 0, my engine RPM's were 850.

 

1. Don't be scared, it's easy. Getting the seized screws off is the hardest part.

2. A lot of us have this: https://www.amazon.com/Hozan-JIS-4-...zan-JIS-4-JIS-Screwdriver-3rd/dp/B00A7WAHTU/ref=cm_cr_arp_d_product_top?ie=UTF8

...the Vessel brand ones are better, but this comes as a reasonably-priced set. You want the #2. Soak with a penetrating lubricant first (I like Aerokroil, lot of people like PB Blaster. WD40 is for chumps). Check the gen3/4 DIY sticky thread, I bet there's an IAC cleaning tutorial in there.

3. Get a cheap ELM327-based Bluetooth OBD scanner from Amazon or eBay. Use with the Torque app (free, but $5 for uber version) on Android, and I dunno on iPhones. You won't look back.

4. If cleaning doesn't fix it, you can just grab the same part number IACV from a Pick-n-pull. These rarely fail outright...just need periodic cleaning.

 

Would you folks recommend for the OP to replace the IACV gasket?

http://www.rockauto.com/en/moreinfo.php?pk=447036&cc=1317493

and if the throttle body is removed, the gasket for it as well? I've heard people just reusing the metal gasket.

http://www.rockauto.com/en/moreinfo.php?pk=477880&cc=1317493


Also OP, your LTFT are right on the spot. Thats really good.

 

Good point. I always replace the TB gasket because crush gasket, and only replace the IAC gasket if it's brittle, worn, or shredded.

 

and if you don't follow isb's and other's recommendations and soak with pb blaster and use a jis #2 with force applied while gently turning, and manage to strip out the heads, there are bolt and nut combos that others have used on her in that case to fasten it back onto the tb.
tony

 

question: If the IACV is to blame for my low rough idle, why does the low sputtering idle only occur when I turn off the vehicle and then restart it a few minutes later? If I drive for an hour and then and idle the car, it runs fine. If I drive for an hour, stop and turn off car for a few minutes and then restart, thats when I experience the low idle and the car wants to stall out.

 

Prob because it's moving/responding to slow, so when you turn your car off after a long drive it doesn't start to close quick enough as the temp of your engine drops so when you go to start it back up the fuel ratio is it right and that's why you have to feather the pedal to give it more gas to keep it going

 

check your air intake hoses between the MAF and your TB for any cracks/leaks. Take them off and stretch them out a bit to visually inspect. I would think a leak here though would cause a high idle. Can you use an OBDII scanner to see if the engine is running in closed/open loop when you do a warm restart? Have you monitored the short and long term fuel trims when you do the warm restart?

 

My air intake hoses look good. My problem is: when engine is warm, I turn off and restart the car, the idle is poor. I rented a scanner (I don't know anything about scanners) it said long term fuel trim? was at 1.6 and 0. I have cleaned my IACV the improper way with initially good results but the problem is returning. I plan on cleaning the IACV the proper way soon. Could someone explain to me why the coolant lines are hooked up to the IACV.

 

they even do it on the cali spec'd cars...never know what's gonna freeze at 115 degrees F....
tony

 

Thanks for the info.....I thought that maybe the temp of the coolant did something to the valve. What controls the opening and closing of the valve?

 

For cold start? ECM monitors coolant temperature.

I want to say the ECM uses it when there's a higher load to maintain idle as well, e.g., quick steering movements. The A/C has its own idle-up valve I think.

 

For the V6 the ECU controls the idle, well tries to control the idle. Often it doesn't do it correctly and won't set the P0505.

The cold coolant in the coolant chamber of the IAC also acts on the thermostat spring under the metal plate. This pushes/rotates on a plastic cup inside and opens the rotor vane.

 

Spring on the ECU controlled IACV's is for fail safe limit only. Coolant flowing through IACV does not control idle speed.

 

could someone confirm the following for attempts at removing the IACV on 1999 v6 Camry:

-use a JIS #2 screwdriver to remove screws from IACV, replace with M5 x .8 x 16 mm hex head bolts
-replace both throttle body gasket and IACV gasket

- if I use a JIS screwdriver and some penetrating oil is there a chance I can do this without a impact screwdriver?

I want to order the right stuff so that the process may be easier than I think, thanks again

 

Yes, yes, and....yes. There's always a chance, but even with a JIS it might strip. When mine stripped, I used a small pair of Vise-grips to get it off.

 

If you're a tool junkie, get yourself one of these. While twisting it CCW, give the end a whack with a hammer and the cams inside rotate the bit CCW. The screw will either loosen, or the head will snap off with the proper JIS bit.

 

Where the hell does one get JIS bits? I've been looking forever

 

thanks, I am ordering the parts today....