Idle Air Control Valve Problem? - Nissan Sentra Forum - B15, B16 and B17 Sentra Forums
 
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post #1 of 6 Old 05-25-2009, 05:06 AM Thread Starter
Auge
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Idle Air Control Valve Problem?

Hey everyone. Did a search to see if i could find an answer to this problem i've been having but came up empty. Any help would be greatly appreciated, i admittedly know next to nothing about my car but would indeed be grateful for some advice. My story is rather long as i figured giving more information would help. Thanks for reading it even if you cant tell me what to do.

So i got a 2001 2.0 Nissan Sentra about a year ago, 6 months into having it when it started it would nearly die. After about a week of that it did die, i spoke with AAA who thought it was a battery problem, so i had AAA bring a battery for the car. Problem reoccured a little while after that but with the addition of my Check Engine Light coming on.

Being right next to a PepBoys i stopped in and paid $85 for a Check Engine Light Check thing. Read Idle Air Control Valve Malfunction. I went somewhere else to get it double checked (free diagnosis this time), same diagnosis, offered to take a look at it, tightened a single bolt and the Light turned off. Seemed to be fixed but came back a little while later.

Now i took it to a mechanic that a friend recommended, free diagnosis again same diagnosis. In addition to the Idle Air Control Valve Malfunction he found that the Starter was bad. Replaced that, replaced the Idle Air Control Valve, but with the new valve it actually worked worse. He then reinstalled the old one and returned the new one only charging me for the work he did.

The light had gone away and it was working better, but again only for a few days. Took it back like a week after he first worked on it, again ordered a new Idle Air Control Valve, same results when he installed it, charged me nothing this time as he again returned the part and had already done the work.

He advised me to speak with a Nissan Dealer, which i will most likely be doing Tuesday, but i thought maybe someone here could save me whatever wad of cash theyd dig out of my cash starved pockets. That mechanic had heard that 2001ish Nissan Sentras often had troubles with the computers that run everything...

Anyway, if anyone knows what might be wrong, or if computer issues are common, or if anyone has any advice on how to broach the subject with the dealer, id be hugely indebted. I've got a trip to Tahoe planned June 1st, and have sunk about $650 into a car ive only had for a year without really solving the problem.

Thanks again for whatever advice you can offer, and sorry for making my first post and my first thread be a request for help but this is driving me rather mad.
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post #2 of 6 Old 05-25-2009, 11:51 AM
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did he try spraying the maf with cleaner? i thought IAC could possibly be Maf related issues... did he do any resets or relearns afterwards?

Any Mods done to your car?

02 Nissan Sentra SER Spec-V || Stereo and Magnaflow Cat-Back
01 Nissan Sentra 2.0 (With PP)|| Brothers DD
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post #3 of 6 Old 05-25-2009, 12:43 PM Thread Starter
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not sure if he sprayed anything and i havent done any mods
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post #4 of 6 Old 05-25-2009, 02:10 PM
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im not 100% sure, but i would assosiate the IACV with the throttlebody. go to the autoparts store and have a look at the replacement... and look for a similar sensor on or behind the throttlebody... i did one on my previous car and it was easy to change out with basic tools.

Dont spray the MAF sensor unless you know its messed up already, you will risk damaging a perfectly good sensor.

Hyundai master technician. Nissan enthusiast. 04 Sentra 1.8S 5 speed, 06 G35 6 speed

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post #5 of 6 Old 12-02-2011, 02:43 AM
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I'm pretty sure you need to do an Idle Relearn after replacing the IACV. Procedure can be found in the FSM but make sure it's the idle relearn for the 1.8 and not the 2.5 as they are different.
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post #6 of 6 Old 12-02-2011, 02:47 AM
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Idle Relearn

Here's the prep for idle relearn:

Idle Air Volume Learning UBS001CI
DESCRIPTION
“Idle Air Volume Learning” is an operation to learn the idle air volume that keeps each engine within the specific
range. It must be performed under any of the following conditions:
 Each time IACV-AAC valve, throttle body or ECM is replaced.
 Idle speed or ignition timing is out of specification.
PRE-CONDITIONING
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
 Battery voltage: More than 12.9V (At idle)
 Engine coolant temperature: 70 - 95°C (158 - 203°F)
 PNP switch: ON
 Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, if the parking brake is applied before the engine is
started the headlamp will not be illuminated.
 Cooling fan motor: Not operating
 Steering wheel: Neutral (Straight-ahead position)
 Vehicle speed: Stopped
 Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “FLUID TEMP SE” in “DATA MONITOR” mode of “A/
T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.

And here's the actuall relearn:

Without CONSULT-II
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic EC-56, "PRE-CONDITIONING" , are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the
result will be incomplete. In this case, find the cause of the problem
by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle speed
and ignition timing are within specifications.

NOTE:
If idle air volume learning cannot be performed successfully, proceed as follows:
1. Check that throttle valve is fully closed.
2. Check PCV valve operation.
3. Check that downstream of throttle valve is free from air leakage.
4. Adjust closed throttle position switch and reset memory. (Refer to EC-87, "Basic Inspection" .)
5. When the above four items check out OK, engine component parts and their installation condition
are questionable. Check and eliminate the cause of the problem.
It is useful to perform EC-143, "TROUBLE DIAGNOSIS - SPECIFICATION VALUE" .
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