5th Generation Maxima (2000-2003) Learn more about the 5th Generation Maxima, including the VQ30DE-K and VQ35DE engines.

Idle air volume learning

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Old Mar 22, 2008 | 04:37 AM
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Idle air volume learning

My 2001 I30 was stalling out as soon as it started up. I tested the IACV and 2 of the 3 coils were bad. I replaced the IACV, and now it runs, but it is going from 1500-1700 (bouncing all the time).

I was thinking it was because I put a thin coat of rtv on the throttle body gasket, because I couldn't get a new one in time. It could be that my intake was very dirty so I ran some seafoam through it to clean it up.

I have read that cleaning the intake could cause a higher idle. This is because other people could have adjusted the idle up with a dirty intake?

I am following the procedure to do the idle air volume learning (without the consult II), and I have all the prereq's met (Trans in park, batt voltage is good, no ac on, no headlights, etc). I have followed every step to a "T", and the idle has not learned itself.

I do not want to adjust the base idle speed, as the flow chart for idle speed/ignition timing states that the idle air volume learning must be done before adjusting the idle speed.
Old Mar 22, 2008 | 12:05 PM
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you have an 01....you adjust the idle by adjusting the throttle cables on the TB....
Old Mar 22, 2008 | 05:31 PM
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Okay. I have slack on both cables, so it should be at the throttle closed switch. I also verified with my OBD2 scan tool that the tps is reading 0%.

So why would it be idling around 1500-1700? Maybe the rtv is clogging up an orfice that it shouldn't be?

Maybe I don't have power to the IACV circuit? I need to find the fuse for that, anyone know what it is off the top of their head . The thing is that the harness is buried when the intake piping is on, making it very hard to read the voltage at the harness.
Old Mar 22, 2008 | 06:05 PM
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You're the second person with the same lack of idle control this week. Check The IACV harness connector pins 2 and 5 for battery voltage with Ign. Switch ON. If you don't get voltage, check fuse # 58. The relay involved here is E 32. Soonerfan........where the hell are you getting the idea that you adjust the "throttle cables" to adjust the idle speed? It's wrong.
Old Mar 24, 2008 | 04:22 AM
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Well I verified battery voltage at pins 2 and 5 at the IACV harness. I also swapped relay E32 (I think it is engine control, but it is located against the radiator) with the rad fan relay because they are both the same type. I don't think I needed to swap them because I had voltage, but I'm just covering everything.

The other strange thing was that my intake was very oily. On my sentra I had a small rectangular gasket under the valve cover that sealed oil from getting inside the intake. I was consuming alot of oil on the sentra- so I changed this part and it consumed no more oil.

I don't seem to consume much oil on the I30, but I wonder if the 3.0 has one or two of these gaskets??
Old Mar 24, 2008 | 10:06 AM
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No, there is no air/oil separator or "filter". Just the standard PCV valve system and standard "blowby" hose to the inlet ducting. Oil in the intake upstream of the TB is a function of engine condition and how often you "tromp" on it. Manual tranny cars tend to have more oil in the intake there. Pull the PCV valve out of the camshaft cover and check for vacuum at the end of the PCV valve with the engine at idle. Pull the middle size hose (it's the power steering air control valve hose) off the connector at the intake duct connector block just downstream from the stock air filter housing and check for "some" vacuum at the end of the removed hose at idle. Have you cleaned the crud from the TB bore in the area of the throttle plate? Can you hear the IACV make "noise" when you cycle the Ign. Sw. from OFF to ON and back to OFF? Unfortunately this issue, as you may have already found out can sometimes end up being an ECM problem. Other than checking for the usual vacuum and air leaks and the items above, I've run out of ideas......which are essentially per the FSM.

Last edited by P. Samson; Mar 24, 2008 at 10:08 AM.
Old Mar 24, 2008 | 11:33 AM
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I appreciate all your advice. I have checked all the things you said, because like you said this is pretty much the procedure from the FSM. It can be found by looking for a P0505 code procedure. I never had the CEL for the P0505, but it took me forever to find the info on the IACV stuff.

I do have vacuum at the power steering air control valve, I actually used it to suck up half a can of seafoam to help me clean out the intake.

Along with that, I did clean out the throttle body spotlessly when I was changing out the IACV.

My PCV is only a few thousand miles old, and is a genuine nissan part. I'm not too worried about the buildup if I don't have a air/oil seperator gasket. I'll just make sure I keep up on the seafoam. I can't believe how much the seafoam burnt off.

Before I go and measure out the ECM/ECU pins from the IACV I plan on changing out the throttle body gasket, as I really think the rtv is my problem.

There was only one Nissan dealer in MA who had the $8 throttle body gasket in stock . I have one on order, as it does not seem to be available from the aftermarket stores.

I'll keep you guys updated.
Old Mar 24, 2008 | 11:56 AM
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i removed the TB on my 00 several times to clean it...never used a new gasket. never had a problem.
Old Mar 24, 2008 | 06:36 PM
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Problem found

I pulled my ECU and it is burnt up in one of the large rectangular IC's.

Does anyone know of a reputable ECU repair company that works on our ECU's? I searched on the net and can't really seem to find a company that will work on Nissan ECU's.

I am used to avpro for my Mitsu ECU's but they state on their web page they only work on what they list- and they don't list anything Nissan...

Or, maybe someone has a used one for sale that is reading this thread .

This really sucks because I just had the ECU updated for the new mass air flow sensor.
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