# Engine is slow off line after traffic jam



## KSagal (Feb 18, 2014)

Something I noticed a month or so ago, after getting caught in heavy traffic for a couple of hours going into Boston, in my 2003 Murano with about 115000.

When cold, or from the house, the car is responsive and powerful as it should be. But after it sits in heavy traffic for a while, the engine does not respond to small inputs of the gas pedal. It is almost like it hesitates.

If the car is fairly cool, and still close to home, if in traffic, and we creep forward, the usual is to give it a little gas, and the car creeps forward.

Once the car gets hot (but not too hot, all gauges good) the same input in on the gas pedal gets no reaction. I have to push the pedal nearly to the floor before the engine responds. Then, it wants to jump into full speed, because of the position of the accelerator.

Since I believe I am driving by wire here, my first thought was to the computer, but I am wondering if there may be solution in the exhaust.

Any ideas? Does this sound familiar to something you may have dealt with?


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## smj999smj (Jan 1, 2006)

I doubt that it's the exhaust or the computer. It "could" be the throttle actuator or even a bad sensor. This is really all just guess work. It's impossible to say exactly what's causing the problem without scan tool data and performing the proper diagnostic steps to isolate the cause.


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## KSagal (Feb 18, 2014)

smj999smj said:


> I doubt that it's the exhaust or the computer. It "could" be the throttle actuator or even a bad sensor. This is really all just guess work. It's impossible to say exactly what's causing the problem without scan tool data and performing the proper diagnostic steps to isolate the cause.


Thanks for the response, SMJ, but there is no code. That would be too easy.

I have to admit, I have not installed my diagnostic tool that reads the codes. In addition to the codes, it does check some other items, and I should have checked that, so for the reminder, I say thanks!

I am not overly optimistic however, as I would have thought that if the car knew it was not right, it would toss a check engine light or code of some sort, and it has not.

I thought of the throttle, but since it only does it under certain circumstances, and always resets itself, I was not thinking it was mechanical in any way, but of course, it could be some sort of a partial dead spot on some variable resistor that acts up when hot, or something like that.

Now, that is why I am here. It throws no code so far, so what other diagnostics would you guys (and gals) suggest?


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## SPEEDO (Jun 9, 2003)

when was the last time the trans fluid was changed? also thinking the fluid might be getting too hot... any issues with the trans before now?? might also get your vin number and call your local dealer to see if the trany is still under warranty... do to the year & mileage I would probably do that pretty soon just in case it is still covered


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## KSagal (Feb 18, 2014)

I first thought trany too. I checked the fluid level, clear and good, but I don't know anything about CVT trannys.

Here is my thinking, however. I push the accelerator, and the engine makes no noise, and car does not move. I push harder, and the engine roars and the car jumps. 

I had the unit stuck in the mud one time, (I fix solar installations, so find myself in solar panel fields a lot) and in that case, several months ago, the engine ran well, but wheels did not turn, as all were in soft mud.)

So, in the traffic case, where engine does not respond to accelerator, I am not putting issue at the transmission.

In mud case, I believe it was the all wheel drive/traction control that had difficulty with all wheels slipping equally. That was a tranny issue.

By the way, friend with pickup truck offered to pull me out, and it was un-necessary. He did pull, but at an angle, his trailer hitch to mine, and the side load on the rear tires was all that was needed to make the all wheel kick in, and I drove out in reverse...

Back on topic, I bought the Murano used, and it is an '3 with 110K on it. I think the warranty has most likely sailed a long time ago...


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## smj999smj (Jan 1, 2006)

The CVT warranty was extended to 10 years/120,000 miles. Being a 2003, you'll likely be out on the time issue unless it sat on the lot a really long time until it was sold.


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## KSagal (Feb 18, 2014)

Thanks for all the good data... I'll have to have my mechanic look into this. I do not have a good relationship with any local dealers. I went to two different ones with small projects to check them out, and they both failed miserably in the service department.

Oh well. I will go and look into it just the same...


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## wornwrench (Oct 25, 2014)

2 possibles stick out, As it is a warm/hot issue and throttle based.
1) minor, the air temp. sensor on the air intake may play a part.
2) If this vehicle has an electronic throttle pedal, it or the wires
near the tunnel are getting hot and faulting. check shielding too.


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## KSagal (Feb 18, 2014)

WornWrench, 

Thanks for the ideas. I think it has electronic throttle control, because sometimes I press the accelerator and it does one thing, and sometimes it does another.

If there was a simple cable, that would be hard to make happen, but if it goes to a processor, there are all kinds of variations that could impact...

Great ideas. Thanks. I'll work thru them.


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## SPEEDO (Jun 9, 2003)

any up dates???


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## KSagal (Feb 18, 2014)

No changes or improvements yet. Working too hard, and car still drives well, but the hesitation still exists on hot engine.

I fix solar systems at customer sites, so I spend a great deal of time in this SUV. The problem exists, but is not debilitating the car...

I hope to find some time to check out the suggestions mentioned earlier...


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## quadraria10 (Jul 6, 2010)

Maybe you should try just resetting the ECU? Perhaps it ''learned''some wrong info when stalled in traffic for a couple of hours. Sometimes anything computer related benefits from a reboot. Just unplug the negative on your battery for half an hour or so. Reconnect it, and start the car without touching gas. Let it idle for five or ten minutes. Turn it off. Then try going for a drive. Hope it does wonders for you!


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## KSagal (Feb 18, 2014)

Hey Quad, 

That is a great idea. Simple, to the point and appeals to my sense of logic. I like it, and will try that this weekend. (and report back)


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## smj999smj (Jan 1, 2006)

If you disconnect the battery for that long, you could erase the idle air volume memory and, if you have vehicle dynamic control, the steering wheel position memory. These would need to be relearned with a scantool with the capability of doing these tasks.


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## quadraria10 (Jul 6, 2010)

Thanks for piping in smj, but I must admit you are leaving me at a loss. The purpose is to reset to the original specs and start the relearn proceedings anew. Good point about making sure your wheels are straight before disconnecting battery, but assuming that is done what is the issue? For most repairs its common practise to disconnect the battery. I have done it for brake work, engine work, and sat nav and backup camera installs. Not to mention actually replacing the battery. I never bothered with the peddle resets because I have not had idle or accelerator issues. I also just redid it before cleaning my MAF sensor.
I really think he has more to gain than to lose by trying it.


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## KSagal (Feb 18, 2014)

THanks for the warning about keeping the wheels straight when I do this. (if I do this)

I am not familiar with working on Nissans, and this is my first one, so I am learning a lot as I go along. I am kind of an old Mopar guy, and have not worked on much modern stuff.

One other odd item that happened a few months ago when I bought new tires, was that one of the pressure sensors went off line. Nothing the tire place could do would make it work again, they replaced it with generic, they replaced it again with Nissan parts, etc...

I know they are scanned by the car, and that is how they report. Hand scanners get the signal, car does not.

So, I am ready to disconnect the battery for a short while. I know I will loose data in the radio, I presume some in the GPS, as well as seat and other simple program resets. I will record maintenance counters first (for oil change, tire rotation, etc)

Should I do anything else? My garage is small, tires will be straight. Anything else?


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## quadraria10 (Jul 6, 2010)

Sorry, I thought it went without saying that you would lose radio presets, sat nav set path, trip couter and seat settings. To me that is not a big deal. 
Nissans are good cars, but forgive the heresy, they are no more special than any other make. People put them into storage and remove the battery. You needn't have any fear that by disconnecting the negative cable on the battery you are damaging your car. Even the VDC will relearn with time, but just keep the wheels straight. Thing about modern cars is they self diagnosis and send out error codes when things go beyond a certain threshold of acceptability. You have no codes, but its not performing right. In your shoes, I would try this before spending any money. See what it does. If problem persists or comes back dig deeper, but hopefully you will have an error code to guide you at that point.


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## KSagal (Feb 18, 2014)

Quad, 

As I said, I agree with you, and like your logic. Hopefully, I will have data to share in a day or so.


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## quadraria10 (Jul 6, 2010)

Hey Karl,
You got me curious, so while watching some tennis, I did a little searching re 2003 Muranos and what you describe might be related to an air intake leak. To quote a guy on another forum
''The intake connections are basically a source of air leakage between the Mass Air Flow sensor *attached to air cleaner assembly that covers air filter,
and the intake manifold. There are two rubber flex hoses that attach to a plastic housing using hose clumps, they appear to be the most likely areas for leakage or separation''.

So check those carefully and see if there is any looseness and if clamps can be tightened a bit. Good luck.


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## KSagal (Feb 18, 2014)

Yo Quad, 

You may be a genius!

I checked under the hood, starting at the air cleaner, looking for an air leak. Air cleaner feeds into a 4 inch air hose to a plastic device that looks from the outside like a turbine of some sort, perhaps a vortex inductor, or simply an air valve of some sort... (Mass airflow sensor is in this first hose)

At that point, while the 4 inch continues on to the intake manifold, there is also a 1 inch hose that comes in from the top of the engine. In the old days, I would say the small hose looked like the type that would come from a PCV valve.

That small air hose was disconnected from it's nipple on the engine. Hose clamp was slid about 2 inches too far onto the hose.

I have re-connected that hose, but I have done no more. I will use the car tomorrow, but will likely not know till at least Monday, depending on work. I have to drive the car in certain conditions to see the problem...

Still, the fault I found is very much similar to that you suggested might be the problem.

I will drive and report back.

If all is well, I owe a good meal next time I am in Quebec.


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## quadraria10 (Jul 6, 2010)

Hi Karl
Thanks for the compliment but I am no genius. I was just doing some reading on 2003 Mo and found that what you described was possibly similar. There was a recall on the air intake on your model, maybe it was never done? I do not have the same vehicle or engine as yours so I cannot compare to mine to check what hose your are referring to. Maybe someone else can chime in and confirm the connections for the hose and cap you are mentioning. Hope it works for you.


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## quadraria10 (Jul 6, 2010)

Well sadly Milos lost the Paris final to Djokovic, but between commercials once again more research has revealed that your disconnected pipe is the pcv valve hose. Now the question is why was it disconnected
From Ehow 
Why Does My Car Run Better With the PCV Valve Unplugged? 

By Jay Motes, eHow Contributor

Defective Valve Effects--

A defective PCV valve will fail to vent exhaust gases in the engine. These gases will build up pressure inside the engine, causing oil leaks and other problems. A PCV valve that fails to work properly will restrict the amount of air entering the engine, causing idle problems and reducing fuel efficiency.


Unplugged Valve

If a car runs better with the PCV valve unplugged, the valve is likely not working properly and requires replacement. The unplugged valve allows the exhaust gases to vent through the valve opening, which reduces pressure in the engine from the exhaust gases.

Reasons to Replace

Unplugging the PCV valve can expose the engine to moisture and potentially harmful debris. The unplugged PCV valve allows exhaust gases to escape the engine, increasing vehicle emissions as well as restricting air flow to the engine and in turn causing a reduction in engine performance and an increase in fuel consumption.

So my theory now is that when stuck in traffic for a good while your valve hose is sucking in exhaust laden air while at the same time your engine pressure is getting screwy. And that means your plugging the hose back will quite possibly make your car run worse! Which would be a good thing as its not a very expensive part and you may well have the original still in there.

Within the limits of my genius lol, I think I might be on the right track here. I may eventually deserve a good meal after all, but its probably better that I go to Maine for a good lobster. Hope you have a great day despite the car problems.


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## quadraria10 (Jul 6, 2010)

Of course plugging it back may also make it run better. I am just wondering if it was disconnected by previous owner to make the engine seem better for the sale, or if it worked its way loose over time...


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## KSagal (Feb 18, 2014)

1. I have owned the car for 7 months, and have over 20,000 miles on it. (As I said, I use it for work)

2. I have not noticed the loose hose before, but I also have not looked for it.

3. The hesitant reaction from the engine/tranny only started a short while ago, and it was a change from previous conditions.

4. All of this leads me to believe that the hose was not too likely to have been removed by the previous owner, but anything is possible.

I did take the car for a nice drive today (Sunday) with the wife, and I noticed no change in operation at all, but that hesitation only occurs when engine/tranny is hot from traffic Jam, and I did not experience this today, so this was not a good test drive for this particular problem.

Of course, I did drive 50 miles or so, and I might consider that if the PCV is clogged, it may react in time for today to have been significant.

On Monday I am working on Cape Cod, and while I would usually avoid going thru Boston to get from here to there, I believe I may just go thru the city for the sake of it...

As far as dinner in Quebec or Maine, I am easy. I too am a fan of a good Lobster, so I am good for that. I also have vacationed in Maine recently, where as I have not been in Quebec in 2 decades. (Been to Montreal more recently, but still long ago, and honeymooned in Nova Scotia 17 years ago)

I am looking forward to this test drive tomorrow. Thanks again, in advance of the final resolution, for the efforts thus far...


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## quadraria10 (Jul 6, 2010)

Probably good news that hose got disconnected in the recent past. Hopefully that was the source of your problem, and that you caught it early enough not to do any damage. Fingers crossed. Hope the drive is smooth. Foolish me mistaking Mass and Maine. Cheers.


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## smj999smj (Jan 1, 2006)

Going back to the disconnecting the battery issue:

Late model Nissan ECMs are different from the ECMs they used years ago. On older Nissan ECMs, people would disconnect the battery cable and let it sit to "reset" them. Actually, what they were doing was erasing the self-learning memory. This would set the ECM to base settings programmed into the ECM. This was a big advantage over some ECMs in the day that did not have base settings and had to be relearned; anyone remember the old GM cars that you had to set the parking brake and let it idle in reverse until the ECM did it's relearn? Older Nissan ECMs were non-programmable and when you needed an update, you had to replace the entire ECM. Late model Nissan ECMs are programmable and the same ECM can be used to cover several trims or emissions certifications of the same model; the difference is in the software program, which can be updated with a Consult scantool as needed, rather than replace the ECM, itself. The idle air volume is something that needs to be learned, much like the old GMs. Because certain parameters need to exist, such as specific temperatures of engine coolant and fuel temperature, it is difficult to learn to idle air volume without a scantool. If the memory is lost, it can cause rough idle and stalling or excessively high idle, along with setting a trouble code, usually P0507. It will not necessarily relearn this over time.
As far as the losing the steering wheel position, if this is lost, it will also not relearn itself over time. If, after disconnecting the battery cable and reconnecting it, the VDC/Slip warning lights do not turn off within the first few feet of driving, it will need to be relearned using a capable scantool. There is no way for the VDC system to know where the steering wheel position is without it being learned. It will also set a trouble code for the steering wheel position sensor. Also, if a wheel alignment is performed and adjustments are made to it, a steering position sensor relearn should also be performed.


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## KSagal (Feb 18, 2014)

Purposefully drove the car thru Boston rush hour traffic yesterday morning. At first, it seemed much better, but after an hour in the heavy traffic, some of the symptoms seemed to come back, but not as bad as previously...

I have not checked under the hood for that small hose, but I am now ready to buy and replace that PCV before I do much of anything else...

Still working on it. Still am hopeful of a simple repair...

Regardless of this repair, it will be a long time before I purposefully drive back into Boston at 7:30 AM without an overwhelmingly important reason behind it. Car issues aside, I am not a fan of the Boston area drivers, to say the least.


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## quadraria10 (Jul 6, 2010)

Well no miracle but no disaster either, here is to hoping for more progress.

Smj999, I hate to say it, but you are confusing me. Its common practise to disconnect the battery when doing any work around the engine, when replacing bulbs, changing stereo, replacing battery, storing car... My manual instructs me to do this.
My understanding is that in doing this, I am effectively cutting power to the car's computer, and basically requiring it to do a hard reboot. Effectively it would erase accumulated data, and idle relearn is reset. Same thing can be done by removing the 3 fuses in my Nissan for the ECU. Under what specific circumstances would it not relearn assuming all sensors are good and no internal computer component or connection problem? I can appreciate that if a previous programming glitch is identified there may be a software upgrade, but somehow doubt this is the case for 8 and 11 year old vehicles which would the case for mine and Karl's.
As for the Steering Angle Sensor reset, my understanding is that there is a relearn procedure that involves driving straight at 10mph for 100 feet or so. Also from experience I had an alignment done that had the car tracking perfectly and everything in spec, but the steering wheel was about 6 to 10 degrees off. Turns out they weren't equipped or knowledgeable enough to reset it. Drove well, so I didn't rush to the dealership as was suggested and somehow, magically I guess lol, it gradually reset to dead straight a couple of weeks later.
I appreciate you sharing your knowledge.


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## smj999smj (Jan 1, 2006)

Disconnecting the battery to do electrical repairs or replacement of electrical parts is commonplace to prevent accidentally shorting a circuit. Idle relearn is reset, but still needs to be learned either through the manual procedure, which can be tricky and requires a specific set of conditions and values to be met, or via a scantool, which still needs those same parameters met, but the scantool makes it a lot easier to perform the idle air volume procedure. Nissan started doing this around 2000, when it started using programmable ECMs in certain vehicles. Muranos have this system.
I think it's also important not to confuse the ECM "self-learning" feature, which is used to tweak performance based on driver habits and style, with the learned values that need to be set for proper performance and operation. With a scantool, "self learning" can be cleared or "reset," but that does not affect the learned values, such as the idle air volume.
As far as the alignment, if the wheels are in alignment but the steering wheel is not straight, this means the steering wheel centralization is off. Steering wheel centralization is a part of a proper wheel alignment, so if it was off on the wheel alignment rack and the tech released the vehicle that way, he didn't do the job properly. Centralization is not a hard thing to do and doesn't require special equipment; it could be done using a toe stick of one knows what they are doing. This is different than the steering wheel being centralized, but it being turned either to the left or the right while driving due to a wheel pull condition, usually due to unevenly worn or improperly inflated tires or road crown. 
If you are saying that your vehicle left after an alignment with the wheel in a non-centralized position and that a couple of weeks later it became centralized, this would suggest either you had a pull condition due to unevenly worn tires and they wore correctly with the new alignment and corrected the steering wheel being turned off-center while driving, or, the vehicle's steering hit something or went over a large bump and it altered the alignment in a way to correct the steering wheel position. This would likely mean the wheels are no longer aligned. I can't tell you which.
On vehicles with VDC, the neutral position of the steering wheel needs to be learned to the ABS control unit, which is the main, but not sole, computer in the VDC system. It uses the steering wheel as input to let it know how much the driver is turning the wheel. There is no way for the ABS computer to know this position without it being programmed (or "learned") into the control unit. You are correct in that it is done by driving in a straight line at a given speed, but this is done with a scantool connected and in work support mode for the steering wheel position relearn procedure. If the learned steering wheel position is not accurate, then, when needed, the VDC system may not respond properly. 
I hope this answers your questions properly.


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## quadraria10 (Jul 6, 2010)

Thanks anew Smj, the guy non Nissan did mess up, but I didn't have any accident afterwards. I thought that when I installed a new sat nav a couple of weeks after the alignment, that I somehow reset the steering wheel to center. Its been over a year and the car tracks beautifully, no concerns taking hands off the wheel briefly, steers really nicely.
I don't believe I need one, but next time I will give the Nissan dealer another try. Somehow I think you are a level or two above anyone who works there...
Anyway its interesting to learn about the complexity of the system. I will look at these systems in the servicing manual more closely.
Re Karl's situation would the recent learnings of his system with the pcv hose disconnected, affect short term performance while it relearns with it plugged in?


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## smj999smj (Jan 1, 2006)

If you are referring to his ECM's self-learning, I wouldn't be concerned about it. He just needs to fix the PCV or hose, depending which is faulty.


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## KSagal (Feb 18, 2014)

Been away for a while. Problem still exists. Friend with a new Nissan Juke says his does the same thing. Not sure where to go now...

Car runs well most of the time. IF I don't get stuck in a traffic jam, I go days to weeks without seeing this problem.


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