Hello, my 06 M35 Base (171xxx odo) stalls intermittently while at idle. I notice that the RPMs drop and sometimes go back to normal. Sometimes they drop and the car struggles to stay on, and dies shortly after. This happens only when the engine is warm and has been driven for a while, no certain mileage.

I should so mention that I just replaced the alternator a while back, so I'm not sure if that's the issue. Another thing I should mention is that my interior lights sort of "pulsate" with the engine at all times. I can tell that a load is being put on the alternator when I use any device or say, move my seat, or even open the door.

Now, I purchased the car back in April of last year (2017) and haven't had issues like this (p1757,1759 woes!!). The battery that came with the vehicle is still in there. I took the car to autozone, and was told that the CCA, (cold cranking amps) was at about 500 or 550. So I assume the battery is too small. I'm not sure if that could be the issue.

Does anyone have any possible insight that they could share on this issue I'm having? Any help would be greatly appreciated!

Edit: no SES light either so I'm at a loss here.
-Marcus

The ECU and sensors are designed to provide readings within a specific range of voltages which is why high resistance in ground wires can cause inaccurate gauge readouts (coolant gauge reading high when all is well) or inaccurate data to the ECU for MAF and O2 sensor voltages.

normally stalling is due to intake leaks or a bad idle control valve. Take a look and see if any of your intake boots or hoses are cracked/loose.

next check the battery voltage while at idle and report back. Im guessing in this case it is battery voltage related. Cleaning the battery terminals and grounds is never a bad idea and can only make an improvement.

picoman wrote: ↑

Sat Dec 22, 2018 5:11 am

The ECU and sensors are designed to provide readings within a specific range of voltages which is why high resistance in ground wires can cause inaccurate gauge readouts (coolant gauge reading high when all is well) or inaccurate data to the ECU for MAF and O2 sensor voltages.

normally stalling is due to intake leaks or a bad idle control valve. Take a look and see if any of your intake boots or hoses are cracked/loose.

next check the battery voltage while at idle and report back. Im guessing in this case it is battery voltage related. Cleaning the battery terminals and grounds is never a bad idea and can only make an improvement.

Hey, thanks for the response.

Checked all hoses, found no signs of cracks or looseness...

Battery voltage is between 14.65 and 14.73. Its constantly moving. Will not stop changing.

Revved it, and it went down to as low as 14.14. After that, it stayed around 14.59-14.65

Ok, good. The next logical step would be to reset the idle/throttle positon. See the procedure here

https://forums.nicoclub.com/reset-ecu-a ... 95740.html

I suggest reading through the procedure above to get a feel for what you are trying to accomplish, and then follow along with this video while you are in your car

https://youtu.be/TZJfWQLGUZI

picoman wrote: ↑

Sat Dec 22, 2018 1:59 pm

Ok, good. The next logical step would be to reset the idle/throttle positon. See the procedure here

https://forums.nicoclub.com/reset-ecu-a ... 95740.html

I suggest reading through the procedure above to get a feel for what you are trying to accomplish, and then follow along with this video while you are in your car

https://youtu.be/TZJfWQLGUZI

Actually, I did this, both procedures last night and nothing changed. I thought this would've corrected the issue (I had to do this to my Maxima a while back). After doing this procedure to the M, I drove it around for an hour, and it was doing the same thing.

Bummer, The only other breadcrumb we have to work with is the fact that it only works when the car is warmed up and in closed loop. This would indicate that perhaps the o2 sensors are faulty.

If it were my car I would unplug the 2 upstream sensors and see if the problem persists.

If the problem goes away, i would replace the sensors, if the problem remains, I would look into a replacement throttle body.

What is the condition and age of your air filter?
I would consider cleaning the MAF sensor and if you're able to, see if the throttle body is clean.

picoman wrote: ↑

Sat Dec 22, 2018 4:42 pm

Bummer, The only other breadcrumb we have to work with is the fact that it only works when the car is warmed up and in closed loop. This would indicate that perhaps the o2 sensors are faulty.

If it were my car I would unplug the 2 upstream sensors and see if the problem persists.

If the problem goes away, i would replace the sensors, if the problem remains, I would look into a replacement throttle body.

Ouch... well, I unplugged the sensors... nothing changed but the SES light came on.

You think it could really be that? I hope it isn't!

EdBwoy wrote: ↑

Sun Dec 23, 2018 2:07 am

What is the condition and age of your air filter?
I would consider cleaning the MAF sensor and if you're able to, see if the throttle body is clean.

Filter was changed when I purchased the car, so not too dirty, still close to the original color... and as far as cleaning goes. Just use MAF cleaner? And what about for the throttle body?

The MAF requires specific MAF cleaner. You also MUST remove it from the intake hose to clean it. Then, let it air dry for an hour or two before reinstalling it. I also unhook my battery when doing an MAF clean.

Larz wrote: ↑

Sun Dec 23, 2018 11:37 pm

The MAF requires specific MAF cleaner. You also MUST remove it from the intake hose to clean it. Then, let it air dry for an hour or two before reinstalling it. I also unhook my battery when doing an MAF clean.

Ahhh gotcha. I'll keep that in mind. When you say specific, you don't mean a specific brand of MAF cleaner do you?

Not a specific brand, just buy one that is labelled as "MAF Cleaner".

Larz wrote: ↑

Tue Dec 25, 2018 4:52 pm

Not a specific brand, just buy one that is labelled as "MAF Cleaner".

Alright. So I cleaned the MAF, and throttle body as well while I was at it. Drove it, noticed a slight chang. But last night in a parking lot, its started acting up a bit. Started it, it stumbled, tried to catch itself and died. It was running ROUGH. Engine sounded terrible. Started it again, and it immediately shut off, multiple times. Waited about 30 minutes and started it. It was fine. Fired it up this morning... it was fine again.

I read online that the camshaft sensor could also cause these symptoms. I did have to replace it a few weeks ago. (2nd time since owning the car) could that be part of my issue? Even without an SES light?

Max2M35 wrote: ↑

Fri Dec 21, 2018 6:46 pm

I should so mention that I just replaced the alternator a while back, so I'm not sure if that's the issue. Another thing I should mention is that my interior lights sort of "pulsate" with the engine at all times. I can tell that a load is being put on the alternator when I use any device or say, move my seat, or even open the door.

My first thought was an airflow issue, but reading this and then seeing that you tried cleaning the MAF already I would suspect that the replacement alternator is also bad, or possibly too small a unit for the car. Lights pulsating with RPMs means the battery is not being changed properly while driving. Load from even moving the seat is also something you should never notice. Do you know if you got a "new" OEM unit? Or do you know the amperage output of the unit that was put in?

EniGmA1987 wrote: ↑

Thu Dec 27, 2018 11:44 am

Max2M35 wrote: ↑

Fri Dec 21, 2018 6:46 pm

I should so mention that I just replaced the alternator a while back, so I'm not sure if that's the issue. Another thing I should mention is that my interior lights sort of "pulsate" with the engine at all times. I can tell that a load is being put on the alternator when I use any device or say, move my seat, or even open the door.

My first thought was an airflow issue, but reading this and then seeing that you tried cleaning the MAF already I would suspect that the replacement alternator is also bad, or possibly too small a unit for the car. Lights pulsating with RPMs means the battery is not being changed properly while driving. Load from even moving the seat is also something you should never notice. Do you know if you got a "new" OEM unit? Or do you know the amperage output of the unit that was put in?

All I know is that it was a Duralast replacement, I want to say reman. (I know I'm going to get flack for using AutoZone parts)

it might not be an answer for this, but on my M56x, the Variable Valve Timing-Actuator got metal shards into it which would make it get stuck and have the car run like complete s***. It would idle like s*** after running normal for 10 min and cause random misfires.

SnowNYC1 wrote: ↑

Thu Dec 27, 2018 3:59 pm

it might not be an answer for this, but on my M56x, the Variable Valve Timing-Actuator got metal shards into it which would make it get stuck and have the car run like complete s***. It would idle like s*** after running normal for 10 min and cause random misfires.

Yea someone mentioned that to me a while back.... hopefully that's not the case

Another viewpoint..............ALL engines when tight and new idle much smoother and better, with less ups and downs relative to the slow idle speed they run at. When the engines get older they have more trouble doing that and can show occasional issues like here and when a/c gets thrown on to lug the engine down. it then may misfire a bit and come back to spec speed or it may even die. What when new the engine ran right through with no problem at all becomes an issue on the older engine as it does not have the optimum ring and valve seal it had when new. In short, idle speed 'oomph', or rollover torque, is lacking.

On my Fords with idle air controls and no electronic throttle body I faked the engine into doing much better under those conditions after having troubles like above. The voltage pulsating may be simply the idle is too low, sometimes as little as a variance of 100 or less rpm can do it. On mine I bumped the throttle body butterfly further open to make the idle control choke back more, most setups start from the factory with the idle air open more and the TB is closed more, that later leads to the issue we're talking about here. The reason? The idle control action whatever it is is NOT instant, it takes a fractional second to respond to needed changes and the idle control lagging when it needs to ADD air is what allows the minute window for the engine to die in. You change that by making the idle control SUBTRACT air or close up more, meanwhile the idle is then a bit high instead if low and you spend more time with the TB aircrack open to not stall as easy. Done correctly the adjustment is minimal and does nothing to lose the idle speed spec, the only difference is that you are using the idle control to lower the speed rather than the common raising it that the OEM does. The engine then spends far less % of time down where it can die, it is the momentary speed drops that kill you, the ones up are good and do nothing but help.

When I first came up with the idea I was told that the idle speed is 'fixed' and indeed it is, but you do have a window both below and above it that the idle control method works in and if you tilt that toward your need things work much better. I know my Ford went from trying to die occasionally to never doing it at all and all around idle quality improved a goodly chunk but I still had no hanging idle issues at all. I DID note a slight loosening up of the engine braking at decel (due to the TB butterfly reset) but it was easy to get used to.

I couldn't tell you how to approach this idea on a Nissan and even more if an electronic TB but on one of those I might add a vacuum leak at the TB somewhere (PCV entry point maybe?) to add the extra air the engine needs to pull this off. I would use starting say a 1/16" hole in that leak as a metering start point. If you know how it wouldn't hurt to clean the idle control as it will be moving to another position inside to stay there as compared to before, if any shaft there is gummed up you might have idle problems from that. I cleaned mine at the TB change and zero issues there too.

Too many words to say that when the idle air has to open up then older engine tries to die but closing back off it does not, you then create the pure idle air amount to make one or the other of those happen. It will end up being a bit more than the OEM setting anyway, as older engines need slightly more idle air due to them not being as able to draw a good depression (vacuum) down to pull a certain amount of air from any aircrack for it.

I myself have thought more than once that older cars need modded software that takes care of things like that but if the OEMs did it then we would not want to buy a new car would we? In the old days they did it with 'high mileage' PCV valves which were used past certain mileages on older engines. The valves simply had a bigger restriction in them to pass slightly more air.

Update: sooooo sitting in park, and my guages went dark, and came back on 3 times. RPMs went down and came back up as well... headlights were on. Turned them off, issue stops...

I'm definitely assuming all alternator issues here

https://youtu.be/Tp7CtLmRSXg

Hopefully the link will work

https://youtu.be/K_kF2_76PI0

Issue that I spoke of before.

That is indeed likely a power supply issue.

In addition to checking the alternator to see if it is good, I would replace the power wire from the alternator to the battery with a new, larger gauge one as well as the ground wire from the engine to the battery with a new, larger gauge one.

2 gauge wire for alternator to battery should be the minimum, as that has 180 amp rating for chassis wiring
Ground wires, 4 gauge is plenty fine for things, but the default OEM ground wire for the engine is a measly little 20 gauge

This issue could be something simple as too much rust on your wire connections causing power to not flow right.