DTC/ Stalling

[sub0carfanatic]

Our 2009 QX56 left my wife stranded about a month ago, just died in traffic, she managed to get it started long enough to get to a parking lot out of the way after a couple start and run attempts. We towed it home where it has sat until about a week ago ago, I used an AUTL MP808 Scanner to read the DTC codes, came up as a bad crank sensor, can not remember the code so I cleared all the codes and then charged the battery overnight, started the vehicle and drove it locally around town a few places with no issues. Well yesterday it dies on us while driving down the road, had to call a tow truck, it would not start period, spins over good but no start, so we had it towed home. I ran the scanner and this time no engine fault codes came up, I was expecting the crankshaft sensor code again but nope. Instead it was DTC P0725 which is a input/turbine speed sensor, transmission speed sensor or whatever you call it.( I think) are these 2 related, could it still be the crank sensor? I found part # 31935-97x00 I am not sure if this is it. I would really appreciate any help. I was going to go ahead and order the crank sensor but want to make sure that is what I need and make sure the crank sensor is not the same as the sensor assembly-revolution as the dealer calls it, the part number above is for this sensor assembly-revolution part.

[VStar650CL]

P0725 isn't the turbine sensor, it's the TCM complaining that the ECM isn't sending out an RPM signal. It's derivative from your engine problem. Nissan CKP's often don't throw codes when they're malfunctioning (as opposed to flatlined, which will always cause a code).

To find the right part number for your CKP, visit InfinitiPartsDeal.com and feed it your VIN. They have the same database and drawings as Nissan/Infiniti DPiC, so you'll get the right part every time.

[sub0carfanatic]

P0725 isn't the turbine sensor, it's the TCM complaining that the ECM isn't sending out an RPM signal. It's derivative from your engine problem. Nissan CKP's often don't throw codes when they're malfunctioning (as opposed to flatlined, which will always cause a code).

To find the right part number for your CKP, visit InfinitiPartsDeal.com and feed it your VIN. They have the same database and drawings as Nissan/Infiniti DPiC, so you'll get the right part every time.

Thanks VStar650CL. So it is the crank sensor then, I was wondering. I have part numbers for the crank sensor plus the 3 camshaft sensors, I was told the camshaft sensors should be replaced while replacing the crankshaft sensor, and our QX56 has 3 cam sensors I was told. So 3 cam sensors plus the crank sensor. I think I will start with just the crankshaft sensor. Appreciate the help.

[VStar650CL]

On that generation of VK56, the two upper sensors are strictly for IVT control and generally won't cause serious issues. You can probably leave those alone since there are no codes. The sensor lower down on the front of the lefthand head is the primary CMP, and yes, it's a good idea to change that along with the CKP.

[sub0carfanatic]

On that generation of VK56, the two upper sensors are strictly for IVT control and generally won't cause serious issues. You can probably leave those alone since there are no codes. The sensor lower down on the front of the lefthand head is the primary CMP, and yes, it's a good idea to change that along with the CKP.

I will go ahead and order the cam sensor as well as the crank sensor, I believe all 3 cam sensors have the same part # ( 23731-4M50D ) is what I came up with for the cam sensors and 23731-AL61D is the crank sensor.
Thank you once again for the help VStar !

[VStar650CL]

[sub0carfanatic]

Here is an image ( drivers side ) front of head view, there look to be 3 sensors. Which one is the main one you suggested to replace.
Well it will not let me attach an image keeps saying error, never had that happen. Can not drag the image in nor use the attachments tab, error.

[VStar650CL]

There are two on the driver's side head, one is located higher than the other. You want the lower one.

Is the pic too big, maybe? There's a size limit. I keep mine to about 1500 px on the long axis and never have issues.

[sub0carfanatic]

There are two on the driver's side head, one is located higher than the other. You want the lower one.

Is the pic too big, maybe? There's a size limit. I keep mine to about 1500 px on the long axis and never have issues.

Here it is, I downsized it. This is the Left side ( Driver side )
The one on top, the one on the right side middle and one in the lower middle area. I tried unplugging the one on the right side middle that has the green inside the plug, it will not come unplugged, I hope this is not the one that has to be replaced because I tried disconnecting it for about 45 minutes with no luck. I had the sensor out but plug will not come off, all the others have the push in and pull tab and came easy but not that one.

[sub0carfanatic]

Here is the plug from the right side middle sensor I pulled out to remove but could not disconnect it so I put but back in. I hope this is not it, I have never seen a plug like this that just would not come out, not sure if there is a tab missing from being worked on previously but I tried everything I could.

[VStar650CL]

VK Sensors.jpg (42.53 KiB) Viewed 5109 times

Slide Detent Connector.jpg (38.17 KiB) Viewed 5109 times

The connectors can be very stubborn if they get dirt inside. Spray the slider with WD40 and if necessary use a small channeloks to pinch the slider into the housing. Don't feel bad, guys butcher those all the time not realizing the green part is a slider that you push and not a pawl relief that you pinch.

[sub0carfanatic]

I got the crank sensor off the transmission, it had the same type green push in tab as the one up top did, I have never seen any like that. I got them both off and will get them ordered tonight probably.
I can't thank you enough for your time and all your help, it has been invaluable. Much appreciated VStar! I will let you know how it goes after the installation.

[sub0carfanatic]

Well I replaced both of the sensors, the crankshaft sensor that was on the transmission part # 23731-AL61D and the camshaft sensor on the lower driver side head part # 23731-4M50D. It still will not start. It spins over 90 to nothing but will not start. I assume those part numbers are correct for the given locations where they were installed. After I installed the parts and connected the battery I hooked up the Autel scanner and there was no codes except the ICC Cruise code which is always present because our cruise has never worked since we purchased the vehicle. So what's next, air, fuel or spark and how to check them on this vehicle? I am pretty sure I can hear the fuel pump kick on and hum every time the key is turned off then back on. Could a fuel filter on this vehicle plugged cause it to die while driving then not re-start? It should not be a coil since they would probably all have to be bad for it to not start, does not seem likely. Could it be one of the other remaining cam sensors that I did not replace, not sure since no codes are present at the moment. I am not sure at the moment what to check for next.

[VStar650CL]

If your scanner will stream the IVT angles, make sure your timing isn't jumped on one or both chains. There's no fuel filter besides a screen in the pump, but the Titan/Armada fuel pumps (and your QX by extension) are notorious for causing mystery stalls before they die. The connectors are also infamous for burning up ground pins. The easiest check for no-fuel is to pop the top on the airbox and spray something combustible like Gumout or Brakleen straight down the barrel while an assistant cranks. If it fires and runs then your pump ain't pumping.

[sub0carfanatic]

If your scanner will stream the IVT angles, make sure your timing isn't jumped on one or both chains. There's no fuel filter besides a screen in the pump, but the Titan/Armada fuel pumps (and your QX by extension) are notorious for causing mystery stalls before they die. The connectors are also infamous for burning up ground pins. The easiest check for no-fuel is to pop the top on the airbox and spray something combustible like Gumout or Brakleen straight down the barrel while an assistant cranks. If it fires and runs then your pump ain't pumping.

Wont it need to be running to do this?

[VStar650CL]

No, you should be able to stream angles while cranking. They should read near zero on both banks. Putting supplemental fuel down the barrel is to see if it does start and run, if it doesn't then you can eliminate fuel starvation as the cause.

[sub0carfanatic]

No, you should be able to stream angles while cranking. They should read near zero on both banks. Putting supplemental fuel down the barrel is to see if it does start and run, if it doesn't then you can eliminate fuel starvation as the cause.

I
Yeah I understand, I have the air filter top with tube off so i can spray starting fluid in the throttle body, I thought about it yesterday but ended up looking at the ECM relay that I read is a common issue that causes it to just die, I put the fog light relay in place of the ECM relay but it still did not make a difference. Thanks for your help again for your help VStar.

[VStar650CL]

Starting fluid isn't a great idea, it's much more volatile than gasoline. If it burps you'll lose all the hair on your eyebrows (not to mention maybe hurting the engine or throttle body). Get some Brakleen from the parts store, it's much safer.

[sub0carfanatic]

Starting fluid isn't a great idea, it's much more volatile than gasoline. If it burps you'll lose all the hair on your eyebrows (not to mention maybe hurting the engine or throttle body). Get some Brakleen from the parts store, it's much safer.

Ok, I have several cans of that brakes parts cleaner in the garage. Thanks!

[sub0carfanatic]

Will this type work VStar? Just a squirt or two in the throttle body?

[VStar650CL]

Yep, that'll work fine. Ideally have somebody crank it while you spray, but if you don't have an assistant, give it about a 5~6 second shot and then crank it yourself. They'll usually run about 10 seconds on that amount.

[sub0carfanatic]

If your scanner will stream the IVT angles, make sure your timing isn't jumped on one or both chains. There's no fuel filter besides a screen in the pump, but the Titan/Armada fuel pumps (and your QX by extension) are notorious for causing mystery stalls before they die. The connectors are also infamous for burning up ground pins. The easiest check for no-fuel is to pop the top on the airbox and spray something combustible like Gumout or Brakleen straight down the barrel while an assistant cranks. If it fires and runs then your pump ain't pumping.

This is the Intake Valve Timing angle you speak of correct? ( IVT) correct? I did not see that abbreviation on the scanner , I will check again tomorrow, I took a short video and picture to share, could not share the short video, it was live data while cranking the engine over several times. Still learning about the scanner I have, its an AUTEL MP808 PRO. I will try to share an image I took, not sure if this is the IVT angle but I believe it is, I took picture while cranking on the engine.

[sub0carfanatic]

The above image is with key on but not cranking. I will try and share a second image while cranking, wish I could share the live data short video clip with you so you could better see. This is only (b2) I realize I need both if this is correct.
Below image is while cranking.

[sub0carfanatic]

I will get some better pictures tomorrow. and try again.
I will also try shooting BRAKLEEN in the throttle body, but I believe I could smell gas while cranking on it a few times yesterday and I can hear the fuel pump kick on with key turned on. Will check tomorrow though.

[VStar650CL]

Yes, Int/v tim is the correct parameter and you should look at both banks. On most Nissan engines they should read near zero when cranking (some 4-bangers actually have a cam lock to keep it at zero till the engine starts). The readings should only move much when you blip the accelerator with the engine running. If the readings are unequal it means either a bum sensor or a jumped chain. If they're both off much from zero, that's almost always a jump.

[sub0carfanatic]

Yes, Int/v tim is the correct parameter and you should look at both banks. On most Nissan engines they should read near zero when cranking (some 4-bangers actually have a cam lock to keep it at zero till the engine starts). The readings should only move much when you blip the accelerator with the engine running. If the readings are unequal it means either a bum sensor or a jumped chain. If they're both off much from zero, that's almost always a jump.

What causes it to possibly jump time so easy? I will take a few images today, This job is starting to look like something a shop will have to do, if it has in fact jumped time because of a bad Crank/cam sensor that is going to involve some major work and tearing the whole front end off to get to everything probably. I am working in my driveway and do not have a garage to do this in, I was hoping this would be just a crank or cam sensor replacement job, we will see I guess , can't believe this could turn into a re- timing job just from a bad sensor. I will let you know the results after running the scanner this morning. Thank you for your help VStar.

[VStar650CL]

They can't jump time because of a sensor, but a sensor can read the timing incorrectly. That's why if one side is off, you try a sensor first before assuming a chain has jumped. On VK engines it's actually pretty unusual for both chains to jump, because they don't use a main chain and two subchains like a VQ. There are just two long main chains, one for each head. Since jumps usually happen from worn chain guides, when a VK jumps, it's usually just one bank.

[sub0carfanatic]

Ok, I have some images to share, hopefully they are good enough for you to see the numbers on the bar graph.
So Int/v sol (b1) (%) is the 1st image with a gold color flatline that stays at 0 even when trying to crank.
So Int/v sol (b2) (%) is the 2nd image with a blue flatline that stays at 0 even when trying to crank.
So Int/v tim (b2) (Ca) is the 3rd image that starts off with a red flatline then spikes up to I believe 50 when I first start cranking and as i continue cranking you see in image 4 it drops back down to the same value as where it started but not a smooth flat line its jagged but consistent.
What do you make of this VStar? If you look at the value of image 4 while constant cranking it stays between -7 and 21.5 on the graph, is that around 0 ? The spike up to 50 is only momentarily when I first hit the key but I am not sure what that means. I appreciate your help and all your efforts.
One more question, on the CRC Brakleen does it need to be the non chlorinated flammable stuff or the stuff I shared a image of that says non flammable?

[sub0carfanatic]

Image 1

[sub0carfanatic]

Image 2