My 2001 Pathfinder has gradually "acquired" this little problem... While driving, it runs great. I'll try to describe what happens when I pull up to a stop light:-engine idles down to 750 rpm exactly as expected.-after 25 seconds exactly (I've timed it), the idle speed drops down to 500 rpm or lower.-sometimes, the engine stalls out at this point-if the engine does not stall, it takes a couple seconds and then comes back up to 750 rpm

One interesting thing that I kind of stumbled upon by accident relates to this thread:zer...valveThe thing I was asking about is the Swirl Control Valve (SCV) tank. It's basically a one-way valve with a vacuum accumulator tank on it. If I disconnect the hose from that tank and run the engine, this idle stall problem I described does not happen. Although it threw me a P1130 (Swirl Control Valve Solenoid problem) code as expected.

I've tried the Idle Air Volume Learning procedure as described in the FSM but the problem remains the exact same.

If anyone has any thoughts, I'd appreciate the input.

Modified by theppler at 8:21 AM 9/25/2008
Modified by theppler at 8:22 AM 9/25/2008

having similar problems, wondering if anyone could help this guy and me as well sort this issue out.

There are more components involved. There might be a clue in the fact that the valve should behave differently based on the engine temp. It could be stuck either open or closed all of the time. There is an extensive trouble-shooting section in the manual that I have I can e-mail it to you.

Thanks Lawless. That does help me understand more about the SCV stuff.

From what I am reading there, it seems that the SCV only really opens above 3600rpm. I thought it would have been at lower RPMs than that in a V6.

The crazy thing is that it is like clockwork. 25 seconds after the motor has been running at 750rpm, something must click and the engine speed drops. I suppose I could check these SCV solenoids to see if they are actuating at idle speeds for some reason.

Since I wasn't getting many responses from this section of the forum, I also reposted this question in the Online Mechanic section here:zerothread?id=370007

To summarize that thread, "pm_page6776" believes I may have a bad Mass Air Flow sensor. I will repost my test results here next.

I did some diagnostics on the MAF sensor itself. Here is what I measured on the output of the sensor (in brackets are what the field service manual says it should be):-Ignition switch on, engine stopped: 1.22V (should be approx 1.0V)-Idle, normal operating temperature: 1.56V (should be 1.2-1.8V)-2500 RPM, 2.05 (should be 1.6 to 2.2V)So it looks like it is reading a little high but still within spec.

I also did some diagnostics using my OBDII scanner and found the following:

At 0 RPM:-MAFS reads 1.92g/s-Short Term Fuel Trim (Bank 1) reads 0%-Long Term Fuel Trim (Bank 1) reads -3.9%-Short Term Fuel Trim (Bank 2) reads 0%-Long Term Fuel Trim (Bank 2) reads -3.1%At 762 RPM (idle):-MAFS reads 5.11g/s-Short Term Fuel Trim (Bank 1) reads -19%-Long Term Fuel Trim (Bank 1) reads -14.1%-Short Term Fuel Trim (Bank 2) reads -18%-Long Term Fuel Trim (Bank 2) reads -13%At 2575 RPM:-MAFS reads 12.62g/s-Short Term Fuel Trim (Bank 1) reads -0.8%-Long Term Fuel Trim (Bank 1) reads -14.1%-Short Term Fuel Trim (Bank 2) reads -2.3%-Long Term Fuel Trim (Bank 2) reads -13.3%

I don't fully understand what these fuel trim percentage numbers mean.

Is it strange that all numbers are negative at all engine speeds?

I e-mailed the related section of the service manual for your engine to you. Technically, it's from the QX4, but it's the same engine.

I am experiencing the same exact problem with my 2001 pathfinder. I timed mine, and you were dead on with the 25 seconds. This is a very frustrating problem. I would appreciate any help with this. You obviously have a better understanding of mechanics than I do, so any information I need to pass on to my mechanic is appreciated.

Thanks

Were you ever able to fix this issue with the idle stumbling after 25 seconds? I am having the same problem. The dealership told me it was the idle air control valve motor, but I tested it with an ohm meter as recommended in Chilton manual and it appears to be fine.

Whatever the cause of the problem is it appears to be getting worse because the motor has started making a noise I've never heard before in the 92K miles that I've had it. I sounds similar to a Jeep engine now (it's that weird wheezing sort of noise that's so noticable especially in Jeep Cherokees when you first start them).

wouldnt a severe misfire cause this?

http://www.youtube.com/watch?v=mf_6UoXtSWw

It could, but then the true question is what the root cause of the misfire. Since the original poster's issue is exactly like mine I'm hopeful that he discovered the root cause and will share it with me so I don't waste a bunch of money and time trying things that don't work.

Thanks for your post!

Nuisance Nissan wrote:Were you ever able to fix this issue with the idle stumbling after 25 seconds? I am having the same problem. The dealership told me it was the idle air control valve motor, but I tested it with an ohm meter as recommended in Chilton manual and it appears to be fine.

Whatever the cause of the problem is it appears to be getting worse because the motor has started making a noise I've never heard before in the 92K miles that I've had it. I sounds similar to a Jeep engine now (it's that weird wheezing sort of noise that's so noticable especially in Jeep Cherokees when you first start them).

Strangely, this problem has not happened to me again in about 4 months. I haven't changed anything and it just purrs like a kitten while idling. The only thing I can attribute it to is the cold weather (I live in Canada). Spring is starting to emerge here so I fully expect the problem to be back as soon as it warms up enough.

My next thing to try was going to be a new MAF sensor since they seem to be problematic with these Nissans. If the problem does re-appear for me, I'll definitely add my results to this thread. Please let me know if you come up with anything.

I'll be sure to post if I ever figure out the cause.

I have been blessed in that Nissan moved their North American headquarters to town recently and a ton of the people who work at their corporate office have moved into my neighborhood. I discovered that the guy across the street a “Jedi Master” of unexplained Nissan issues and helps them figure out the problems that no one else can solve when they roll out a new model. Fortunately he had pity on me and agreed to take a look at my vehicle.

After pulling a wicked looking diagnostic machine out of his trunk hooking it to my car and driving it around the block, he pulled out my aftermarket air filter (manufactured by a company whose name starts with K & likes to oil their filters) I installed a few months ago and proclaimed, “Here’s your problem.” Because these filters are oily, the oil can affect the mass air flow sensor. He pulled the mass air flow sensor and there’s a small silver wire inside of it that is supposed to be clean and shiny. Mine was dark and grimy. He gave the wire one extremely light blast with some carb cleaner and I bought a genuine Nissan filter and my idle issue is gone! (As I was buying my filter I was telling the guy in the parts department my story and he said he’s seen numerous instances in which an aftermarket filter has been the root cause of an issue).

Now if I can get back the $90 diagnostic fee that I paid to the local dealership who incorrectly said it was the idle air control (IAC) valve I’ll be good. Luckily I doubted their diagnosis enough that I didn’t pay them the $500+ to install one and I didn’t shell out $240+ to buy one to install on my own!

I may even write to filter manufacturer and see if they’ll give me my money back since they claimed the filter would work with my vehicle and improve performance, etc. and it clearly didn’t.
Modified by Nuisance Nissan at 4:20 PM 4/6/2009

Wow! You are definitely a lucky guy to have a Jedi like that around.

That is very interesting about the K&N oil. I also run a K&N filter in mine. Now that you are mentioning that, I remember that I did clean my MAF sensor a few months back (in the same way that you are describing). I was pretty sure I still had the problem after doing that though.The weather is warming up here and I am a bit surprised that I haven't seen the problem since last fall. Fingers crossed.

Thanks very much for the detailed solution to your problem.