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Idle air valve not working

Tiny
POSTB8822
  • MEMBER
  • 1999 TOYOTA CAMRY
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 300,000 MILES
After a recent timing belt replacement where battery was disconnected. My car suddenly started idling somewhat slowly and has no fast idle when cold. It idles between 450 rpm and 690 depending on temperature, and it bounces a little bit. It smells and seems to be running really rich at idle. I am a decent mechanic and have been scouring the internet for a solution.

I assumed the ECU reset had caused it and first just drove it awhile.

I cleaned the IAC and TB, then replaced the IAC valve, if anything it got a little worse.

I tore apart the timing belt again and verified the timing was correct. It was, and the car runs fine above idle, no power loss, it does hesitate now when setting off from a stop.

I checked the coolant temp sensor with a obd tool, seems to register fine, gives steady temperatures, I checked resistance with a multi-meter and it behaves as expected as it warms up.

There are no codes stored, the fuel and O2 system reports running in closed loop so the O2 sensors seem to be working.

I replaced the spark plugs.

I found a test for the IAC circuit where you jump two pins in the diagnostic port under the hood, it does not idle up as expected. Which is my only clue.

I have voltage 13V when running at the IAC valve between the middle pin and either outside pin.

This seems like an IAC issue to me but a clean and replace didn't help.

Since replacing IAC valve didn't help, finally I bought a used ECU on eBay and swapped it, no change at all. Ugh I really thought that would fix it. I am all out of ideas.
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Thursday, January 2nd, 2020 AT 7:48 AM

14 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

You have done a lot. The one thing I noticed you didn't mention was checking for engine vacuum leaks. That can cause an idle issue. Also, I noted you check for codes, so I suspect you have a scanner. If it is a live data scanner, can you let me know what the fuel trims are. I would specifically like to know the short term fuel trims.

Also, by any chance did you confirm there is nothing blocking the air passage allowing air to enter the engine via the IAC? Note in the pic below how air flows.

I'm not sure if you need it, but here is a link that explains how to check for a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know.
Joe

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Thursday, January 2nd, 2020 AT 10:51 PM
Tiny
POSTB8822
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I added 3 data screenshots from idle 1500 and 2500 rpm. Short term trim bounces a lot but generally at idle it's plus minus 2, long term is locked on -14.8 at idle but when driving is around 0, at higher no load rpm it sits at -9.4 steady. O2 sensor 1 in header bounces.1 to.8, sensor 2 after cat is 0 to.1 whenndriving. Steady 0 at idle. I did hunt for vacuum leaks, couldn't find any. Any tricks to try on that? MAP seems low enough. I put some vacuum to EGR valve at idle and engine chokes instantly. If I pull a vacuum line and leak air the idle shoots up to 1200. How can I test EGR for leaks?
I took throttle body off completely when I changed IAC and cleaned completely all passages were open.
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Friday, January 3rd, 2020 AT 8:18 AM
Tiny
POSTB8822
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  • 11 POSTS
And Thank you for helping!
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Friday, January 3rd, 2020 AT 8:18 AM
Tiny
POSTB8822
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One more sensor, throttle position shows 10.2 at idle 12.5 at 1500 and 14 at 2500 no load.
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Friday, January 3rd, 2020 AT 8:21 AM
Tiny
POSTB8822
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The car is old, I'd like to get another year or two out of it, I'm under no illusion that it should run perfectly, I can live with the somewhat rough idle, but the lack of proper cold start fast idle here in Minnesota is the big issue. It barely starts on days below 10F, choking and needing me to give it gas to keep running, and it's never done that before. I just can't figure out what I could have done to cause it by changing timing belt. I have done that job before two times with no issues.
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Friday, January 3rd, 2020 AT 8:30 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
I looked through the pics you attached. Was the engine warm when you did the test? I noted the engine at 208°F and the air intake at 55°F. Just curious. As far as the egr leaking, based on fuel trims, I would say the problem isn't a vacuum leak. However, here are the directions for testing the EGR system. The attached pics correlate with the directions.
_________________________________________

1999 Toyota Camry CE Sedan L4-2164cc 2.2L DOHC (5S-FE) MFI
Component Tests and General Diagnostics
Vehicle Powertrain Management Emission Control Systems Exhaust Gas Recirculation EGR Valve Testing and Inspection Component Tests and General Diagnostics
COMPONENT TESTS AND GENERAL DIAGNOSTICS
1. INSPECT EGR SYSTEM

pic 1

a. Inspect and clean the filter in the EGR vacuum modulator.
1. Remove the cap and filter.
2. Check the filter for contamination or damage.
3. Using compressed air, clean the filter.
4. Reinstall the filter and cap.

HINT: Install the filter with the coarser surface facing the atmospheric side (outward).

Pic 2

b. Using a 3-way connector, connect a vacuum gauge to the hose between the EGR valve and VSV.
C. Inspect seating of the EGR valve.
Start the engine and check that the engine starts and runs at idle.

Pic 3

d. Using SST, connect terminals TE1 and E1 of the DLC1.
SST 09843-18020

e. Inspect the VSV operation with the cold engine.
1. The engine coolant temperature should be below 55° C (131° F).
2. Check that the vacuum gauge indicates zero at 2,500 rpm.

Pic 4

f. Inspect the operation of the VSV and EGR vacuum modulator with the hot engine.
1. Warm up the engine to above 60° C (140° F).
2. Check that the vacuum gauge indicates low vacuum at 2,500 rpm.
3. Disconnect the vacuum hose port R of the EGR vacuum modulator and connect port R directly to the intake manifold with another hose.
4. Check that the vacuum gauge indicates high vacuum at 2,500 rpm.

HINT: As a large amount of exhaust gas enters, the engine will misfire slightly.

G. Remove the vacuum gauge, and reconnect the vacuum hoses to the proper locations.

Pic 5

h. Inspect the EGR valve.
1. Apply vacuum directly to the EGR valve with the engine idling.
2. Check that the engine runs rough or dies.
3. Reconnect the vacuum hoses to the proper locations.

HINT: As exhaust gas is increasingly recirculated, the engine will start to misfire.

I. Remove the SST from the DLC1.
SST 09843-18020

2. INSPECT EGR VACUUM MODULATOR

pic 6

a. Disconnect the vacuum hoses from ports P, Q and R of the EGR vacuum modulator.
B. Block ports P and R with your finger.
C. Blow air into port Q, and check that the air passes through to the air filter side freely.

Pic 7

d. Start the engine, and maintain speed at 2,500 rpm.
E. Repeat the above test. Check that there is a strong resistance to air flow.
F. Reconnect the vacuum hoses to the proper locations.

Pic 8

3. INSPECT EGR VALVE
a. Remove the EGR valve.
1. Disconnect the 2 vacuum hoses from the EGR valve.
2. Remove the 2 bolts 2 nuts, EGR valve and 2 gaskets.
B. Check the EGR valve for sticking and heavy carbon deposits.
If a problem is found, replace the valve.
C. Reinstall the EGR valve.
1. Temporarily 2 new gasket and the EGR valve with the 2 nuts and 2 bolts.
2. Tighten the nuts.
Torque: 13.3 N.M (136 kgf. Cm, 10 ft. Lbf)
3. Tighten the bolts.
Torque: 10 N.M (102 kgf. Cm, 7 ft. Lbf)
4. Connect the 2 vacuum hoses to the EGR valve.

4. INSPECT VSV FOR EGR

__________________________________________________

Let me know if this helps.

Joe
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Friday, January 3rd, 2020 AT 10:52 PM
Tiny
POSTB8822
  • MEMBER
  • 11 POSTS
Yes the car was warm. Idling in my driveway for quite awhile. Fans were cycling as expected, they cycle on at 212F. Thermostat is good. Going down the road the temp is a steady 185F. The only time I ever hear the fans run is with extended idling. I will do EGR test tonight.
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Monday, January 6th, 2020 AT 2:40 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
The fans sound normal. When you are moving in cold temps, there is no need for them to run. Let me know about the test results.

Take care,
Joe
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Monday, January 6th, 2020 AT 8:12 PM
Tiny
POSTB8822
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EGR checks out okay. Any other ideas?
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Wednesday, January 15th, 2020 AT 2:16 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Are you sure there are no vacuum leaks, unplugged sensors, or leaks?

Joe
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Thursday, January 16th, 2020 AT 4:06 PM
Tiny
POSTB8822
  • MEMBER
  • 11 POSTS
First off let me say I appreciate your assistance. No unplugged sensors, no vacuum leaks that I can find. If I pull a vac hose off the idle shoots up higher. To me it seems starved for air. Why does the IAC valve test fail? You said based on my fuel trims you didn't suspect vac leak any more. Still seems like the IAC valve is just not working. Maybe I got a bad part.. I don't know what else to think. Today it was about 10 below and it was stalling at corners and really surging at idle. Maybe I'll donate it for the tax break :)
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Saturday, January 18th, 2020 AT 5:37 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Hi,

It is possible the part is faulty. The looping you described is typical for a bad IAC. I asked again about vacuum, because things change. Is the IAC under warranty?
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Saturday, January 18th, 2020 AT 5:48 PM
Tiny
POSTB8822
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It was a bad "new" IAC. I'm so mad. I hunted this beast forever. Finally last night I cleaned the heck out of the original IAC and put it back on. Runs fine. Fast idle is back when cold and idles down to about 750 once warm.

So here's what I assume happened: My IAC was dirty and had limited motion. Battery disconnect for timing belt job reset ECU and it was not able to learn idle again with dirty IAC. So my first diagnosis was correct. However since I just replaced the IAC and assumed then that it wasn't the fix because it didn't help, the wild goose chase started. I should have just cleaned it from the get go. I did try spraying carburetor cleaner in it but didn't try too hard since it was only $35.00 on eBay. Probably a bad Chinese knock off.

Thanks for the help.
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Thursday, February 6th, 2020 AT 9:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,867 POSTS
Wow! I'm glad you got it fixed. I learned a long time ago that all parts are not equal. LOL At this point, and because I don't want to do the job twice and have an upset customer, I only accept certain aftermarket brands. People are importing parts from overseas for next to nothing, selling them cheap (and still making a ton of money) and the consumer is the victim.

Regardless, it's good to hear you got it taken care of. Please feel free to come back anytime you have questions or need anything.

Take care,
Joe
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Friday, February 7th, 2020 AT 10:56 AM

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